This PDF file contains the front matter associated with SPIE Proceedings Volume 8562, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

THz wave air photonics involves the interaction of intense femtosecond laser pulses with air or selected gases. The very air that we breath is capable of generating and detecting THz waves with field strength greater than 1 MV/cm and useful spectral coverage from 0.1 THz to 60 THz. Broadband THz wave remote sensing is feasible.

Fourier transform spectroscopy (FTS) is a measurement technique widely used in characterizing the spectrum of light sources and the frequency response of detectors. Some “ghost” spectral lines, however, are often observed in measured Fourier transform spectra, such as high-frequency harmonics of the light source due to multiple reflections in the measurement system and unexpected high frequency lines owing to low-frequency interferences in the data acquisition. Here we study the effects of multiple reflections and low-frequency interferences on the THz spectra measured by a Fourier transform spectrometer for different THz sources and detectors. Experimental and simulation results will be presented.

InGaAs near-infrared (NIR) focal plane arrays (FPA) have important applications in space remote sensing. A design of 800×2 low-noise readout integrated circuit (T800 ROIC) with a pitch of 25 μm is presented for a dual-band monolithic InGaAs FPA. Mathematical analysis and transient noise simulations have been presented for predicting and lowering the noise in T800 ROIC. Thermal noise from input-stage amplifier which plays a dominant role in ROIC is reduced by increasing load capacitor under tradeoff and a low input offset voltage in the range of ±5 mV is obtained by optimizing transistors in the input-stage amplifier. T800 ROIC has been fabricated with 0.5-μm 5V mixed signal CMOS process and interfaced with InGaAs detector arrays. Test results show that ROIC noise is around 90 μV and input offset voltage shows a good correspondence with simulation results. 800×2 InGaAs FPA has a peak detectivity (D*) of about 1.1×10¹² cmHz^1/2/ W, with dynamic range of above 80dB.

Based on transformation optics and complementary media (folded geometry), levitative carpet cloak and overlapping effects (anti-mirror effects) can be realized. In common case, the levitative carpet cloak is limited by the shape of the hidden object, and the early folded geometry method can just make two objects with different shapes appear as only one. Here, based on transformation optics and finite element simulations, we propose an anisotropic but homogeneous shifting media that can shift an arbitrary-shaped object from original place to another place in terahertz (THz) region. As a result, an arbitrary shaped object levitated on a flat perfect electric conductor ground and covered with the shifting media cannot be detected, leading to the levitative and shape-independent carpet cloak. Furthermore, optical overlapping effects such as making two separated objects with the same shape appear as only one, can be also realized by using this kind of shifting media.

As it is well-known, passive THz imaging devices have big potential for solution of the security problem. Nevertheless, one of the main problems, which take place on the way of using these devices, consists in the low image quality of developed passive THz camera. To change this situation, it is necessary to improve the engineering characteristics (resolution, sensitivity and so on) of the THz camera or to use computer processing of the image. In our opinion, the last issue is more preferable because it is more inexpensive. Below we illustrate possibility of suppression of the noise of the image captured by three THz passive camera developed in CNU (Beijing. China). After applying the computer processing of the image, its quality enhances many times. Achieved quality in many cases becomes enough for the detection of the object hidden under opaque clothes. We stress that the performance of developed computer code is enough high and does not restrict the performance of passive THz imaging device. The obtained results demonstrate the high efficiency of our approach for the detection of hidden objects and they are a very promising solution for the security problem. Nevertheless, developing the new spatial filter for treatment of the THz image remains a modern problem at present time.

Thermal Infra Red images are one of the most investigated and popular data modalities whose usage has grown exponentially from humble origins to being one of the most extensively harnessed imaging forms. Instead of capturing the radiometry in visible spectra, the thermal Images focus on the near to mid Infrared spectra thereby producing a scene structure quite different from their visual counterpart images. Also traditionally the spatial resolution of the infra red images has been typically lower than traditional color images. The above reasons have contributed to the past trend of minimal automated analysis of thermal images wherein intensity (which corresponds to heat content) and to a lesser extent spatiality formed the primary features of interest in an IR image. In this work we extend the automated processing of Infra red images by using an advanced image analysis technique called Graph cuts. Graph cuts have the unique property of providing global optimal segmentation which has contributed to its popularity. We side step the extensive computational requirements of a Graph cuts procedure (which consider pixels as the vertices of graphs) by performing preprocessing by performing initial segmentation to obtain a short list of candidate regions. Features extracted on the candidate regions are then used as an input for the graph cut procedure. Appropriate energy functions are used to combine traditionally used graph cuts feature like intensity feature with new salient features like gradients. The results show the effectiveness of using the above technique for automated processing of thermal infrared images especially when compared with traditional techniques like intensity thresholding.

Polarization hyperspectral imagers combine polarization technology, spectral technology and imaging technology, get both the image of the target and the polarization and spectrum of the pixel to recognize the materials on the objects，have broad applied foreground on airborne remote sensing domain. That arrests extensive attention abroad. This paper brings hyperspectral technology and polarization image together. On the basis of geometrical optics theory and polarization theory, puts forward a new polarization hyper-spectral Imaging technology. That could get hyper-spectral information and whole Stokes elements spectral from the object on the measuring the power spectral from the modulator only one time, and that raise the ability of recognization greatly. The paper carries out a project to the new airborne polarization hyperspectral imager.

Infrared probes composed of different hollow fibers were designed, fabricated, and optimized according to their transmission properties. Remote measuring system using the probe was set up with a Fourier Transform Infrared Spectrometer (FTIR). The experimental results showed that the transmission efficiency reached 17.6% when tapered fiber is used as the receiving fiber in the probe. Infrared spectral features were measured for films such as polycarbonate (PC) and Poly vinylidene fluoride (PVDF), as well as liquid-phase films such as ethanol and toluene. Quantitative measurements were carried out for the mixed liquid of ethanol and toluene using the characteristic absorption peak of toluene at the wavenumber of 1605cm^-1. A number of mixed liquid with various concentrations ranging from 5% to 50% were made to build the quantitative model and evaluate the effect of the measurement. The results showed that RMSEP was 3.356 and the correlation coefficient was 0.9200. The system can be used in remote measuring of spectral features for solid and liquid phase films.

A readout integrated circuit (ROIC) for 320× 256 middle-wave and long-wave infrared focal plane arrays, is studied in this paper. This circuit operates in integrating-while-reading (IWR) mode with the frame rate higher than 100fps. A novel DI structure is used for signal acquisition of middle wave while BDI structure for long wave. It is common that trade-offs always exist between chip area and performances in integrated circuits design. In order to get high injection efficiency for BDI structure with small area, a four-transistor amplifier with a gain of 82dB is designed. The charge capacity of ROIC is also a key performance parameter when considering the noise and the large middle-wave and longwave photocurrent (up to 5nA and 100nA, respectively). A structure named double sharing capacitors (DSC) presented in this paper will be an effective solution to getting a large capacity in the limited 50 μm x 50 μm pitch area. DSC means that each integrating capacitor has two kinds of shares. One is between the integrating capacitor and another integrating capacitor which is in the adjacent pixel, and the other is between the integrating capacitor and the holding capacitor in the same pixel. By adopting the 0.35μm 2P4M mixed signal process, the DSC architecture can make the total effective charge capacity as high as 70Me- per pixel with 3V output range. According to the simulation results, this circuit works well under 5V power supply and achieves 2.5MHz data transmission rate, less than 0.1% nonlinearity. Its total power consumption is less than 110mW.

A scheme of format conversion between OOK signal and optical quadrature phase shift keying (QPSK)/16-ary quadrature amplitude modulation (16QAM) signal based on cross phase modulation (XPM) effect in semiconductor optical amplifiers (SOA) is proposed. Theoretical analysis and simulations of the format conversion scheme are conducted to validate the feasibility of the proposal. In this proposal, the QPSK signal is generated after passed an SOA, and then the 16QAM signal is generated based on XPM in a single SOA-MZI after two QPSK signal coupled. The performance and the optimal design of the 10Gbit/s format conversion system under various key parameters of SOAs are evaluated and discussed. The receiver sensitivity of the converted QPSK signal and 16QAM signal after detection is -32dBm and -28.5dBm with BtB at BER of 10^-9, respectively. Simulation results present useful to enable interconnection between backbone network and access network.

Recently, there have been many attempts to converge LED with IT technology. Among them, Visible Light Communication (VLC), which is the convergence of illumination and communication, has emerged. In VLC system, both lighting and communication can be simultaneously implemented. By considering both terms together, VPPM(Variable Pulse Position Modulation) modulation scheme is proposed by the IEEE 802.15.7 standard group. It uses binary PPM (Pulse Position Modulation) for communication and PWM (Pulse Width Modulation) for dimming control. In this paper, we introduce the implementation of VLC demonstration system based on VPPM modulation scheme. By changing the pulse width of VPPM signal, we can support 25%, 50% and 75% dimming. In addition, our VLC demonstration system provides a new power system using solar cell. By receiving the VPPM modulated visible light signal in the receiver end, we turn on the receiver power and start the system operation to decode the transmitted signal. By using ATmega128 8bit Micro Controller Unit (MCU) by ATMEL and Q3 XLamp XP-E LEDs of Cree, our system provides about 2kbps data rate with 2.5kHz optical rate in more than 30cm distance. By implementing DM S/W, we show the bit error rate (BER) and achievable data rate (ADR) of our demonstration system.

Instantaneous frequency measurement (IFM) of input unknown microwave signals is critical importance for modern radar warning receivers in the field of electronic warfare. The photonic techniques have attracted more and more attentions for IFM due to the advantages of wide bandwidth, low loss, light weight, and immunity to electromagnetic interference. In this paper, a photonic approach to IFM with extended range based on phase modulation is presented. In the proposed measurement system, two optical wavelengths and two segment dispersion fibers are used to construct the frequency-dependent amplitude comparison functions (ACFs). Several ACFs can be jointly utilized to determine the microwave frequency without ambiguities beyond a monotonic region of the conventional one ACF. Then the measurable range of microwave frequency can be extended and the accuracy can be improved by selection of ACF with large slope. The operation principle of the photonic approach is illustrated and the experiment results show that the errors are limited within ±0.15 GHz from 8 to 20GHz frequency measurement range.

With the rapid development of space cameras and remote-sensing application technology, photoelectric sensor of the remote sensing satellite have evolved from the single-spectral, single type, single focal plane to the multi-spectral, multi-type, multi-focal plane integration direction. At present, the manufacturing process of the infrared detector has a larger improvement, but compared to the CCD device, the resolution is still low. In order to improve the resolution of infrared imaging systems, infrared imaging system using jointing multi-focal plane array can increase the resolution of infrared imaging systems. At present, remote sensing satellite equipped with a visible light detector and infrared detector, and design of multi-spectral, multi-type, multi-focal plane imaging circuit has become a new challenge. For multi-spectral, multi-, multi-focal plane imaging characteristics of the circuit system, this paper analysis and design of the FPGA signal processing circuit for multi-spectral, multi-focal plane jointing infrared imaging system, which includes time base correction circuit, infrared detector timing control circuit, multi-channel analog signal delay correction circuit, multi-channel uncertainty calibration circuit, average filtering of over-sampling circuit, multi-channel image data reading and correction circuit. Details the various parts of the design ideas and methods, design, simulation and testing. The test results show that the design is correct and feasible to meet the design requirements.

To date, the measurements from AIRS, GOSAT, SCIAMACHY and IASI are widely used to derive atmospheric CO₂ concentration globally. Quantification of the spatio-temporal differences between these CO₂ products is crucial for deeply understanding each product and for exploring the potential for their joint use in the future. A series of processing has been proposed in this paper to unify these existing CO₂ products, so that they can be theoretically comparable. Based on this, the spatio-temporal variations of these CO₂ products have been conducted. The results reveal that AIRS show the largest spatial coverage of CO₂ compared to other CO₂ products. The valid X_CO2 data from SCIAMACHY are mainly restricted to land regions. Even if over the land, the X_CO2 distribution of ACOS is slightly wider than that of SCIAMACHY, especially over the region of Eurasia and North America. An obvious arch-shaped pattern along latitude for ACOS, Japan-GOSAT and SCIAMACHY is detected, while no distinct latitudinal variation can be observed for AIRS. For the seasonal variation, these datasets show a similar trend with the maximum CO₂ loading occurring in spring. The discrepancy between these products implies that it is greatly necessary to better constrain the uncertainties in CO₂ retrieval from space in the future.

This paper reviews the recent advances in high efficiency pulse tube cryocoolers (PTCs) in SITP/CAS for space-borne infrared applications. Due to the special aerospace environment where the power supply is limited and the rejection condition is adverse, the high cooler efficiency is especially emphasized. A brief history of the PTC and the last 30-year worldwide quest for highly reliable and efficient PTCs has been provided as a background. Then our efforts to achieve high efficiency coolers are discussed. Three typical geometrical arrangements, U-type, coaxial and in-line, are all involved, while the latter two are stressed on. Some typical development programs are introduced and a brief overview of the relevant data package is presented. To date, the no-load temperature reaches 25 K, and the typical cooling capacities of 0.9W@40K, 4.5W@60K, 8.0W@80K and 12W@95K have been achieved, respectively. For the mature coaxial coolers, the typical relative Carnot efficiencies of 2.8%, 9.4%, 14.4% and 15.7% has been achieved at 40 K, 60 K, 80 K and 95 K, respectively. For the newly-developed high efficiency in-line PTCs, the corresponding values are 2.9%, 9.6%, 16.2% and 17.8%, respectively. The acquired high efficiencies have made them enabling cryocoolers for the aimed space applications. The batch production of the main components has been realized and the typical EM machines have been worked out.

Terahertz Superconducting Imaging Array (TeSIA) is a project for the development of a large THz direct-detection array for mapping observations. The prototype of TeSIA is an 8×8 pixel direct-detection array operating at the 850 μm band, incorporating THz superconducting detectors such as kinetic inductance detectors (KIDs) and transition edge sensors (TES). KIDs have the advantage that only a broadband low noise cryogenic amplifier is needed at low temperature for the readout system, and hundreds of pixels could be readout simultaneously by the frequency-division multiplexing (FDM) technique. The readout system for a KIDs array is composed of several parts like excitation signal generating, intermediate frequency (IF) circuit, baseband signal acquisition and processing. Excitation signal is a kind of comb signal carrying various frequencies corresponding simply to resonant frequencies of the detectors. It is generated in baseband with a bandwidth covering all KIDs and up-converted to microwave frequency (about several gigahertz) to feed the detectors. With THz radiation, the forward transmission coefficient (S21) of all KIDs varies and the variation can be measured through the comb signal. Fast Fourier transform (FFT) with pipeline structure will be used to process the baseband excitation signal in real time. Consequently, the radiation intensity can be estimated by monitoring the signal amplitude and phase of the corresponding frequency channels. In this paper we will present mainly the design ofan electronic readout system for the 8×8 pixel array.

We present the simulation of an asymmetric double split-ring metamaterials absorber in terahertz region. The device consists of a metal/dielectric-spacer/metal structure allowing us select absorption by varying the asymmetric characteristics. When the two gaps are gradually away from the center in opposite direction, a giant amplitude modulation is observed at the fundamental inductive-capacitive (LC) resonance and the resonant frequencies are observed to red shifting. Besides, increasing the thickness of dielectric-spacer, the peak absorption can be changed. This theoretical simulation will be good reference for the follow experiments, and these asymmetric metamaterials absorbers is expected to be used as cloaking materials.

Theoretical and experimental works were carried out on a double channel mechanically tunable terahertz filter integrated with parallel plate waveguide cavities. The filter includes two rectangular grooves on upper and bottom plates of waveguide, respectively. The filter frequencies can be quasilinearly tuned by altering the overlap length between two rectangle grooves on metal plates. From the experiment, we found low (high) resonant frequency can be adjusted from 0.417(0.346) THz to 0.399(0.374) THz when the overlap length is altered from 0 to 500 μm, respectively. The Q values can reach 46 with the resonant frequency (0.41THz), overlap length (220 μm) and waveguide spacing (650 μm). Theoretical results show good agreement with experiment.

The principle of a novel passive millimeter-wave (MMW) imaging method using frequency scanning antenna (FSA) and arrayed waveguide grating (AWG) is analyzed theoretically. The imaging processes are divided to three stages and discussed respectively. Then the FSA with 33~ 43GHz frequency scanning range is designed carefully with a field of view of ±25°for the MMW imaging system. An AWG of 1×24 is then simply designed with a channel spacing of 0.5GHz. The designing and simulating demonstrated the feasibility to build such an imaging system which is progressing.

In this paper, according to the characteristics of TDI infrared focal plane array output signal, a novel signal processing system based on AC coupling technology is proposed. Firstly, the output signal characteristics of TDI infrared focal plane array are analyzed. Secondly, the signal processing system based on AC-coupled technology is introduced. The designed system is consist of high pass filter circuit, signal conditioning circuit, differential input analog to digital converting circuit and digital data processing circuit. Thirdly, the designed system is simulated and tested. Simulation and test results show that the novel design idea of signal processing circuit is reasonable and feasible. Compared with the traditional design, the system has the characteristics of high common mode noise rejection, low temperature drift and low power consumption.

We present an experimental study on a flexible terahertz (THz) pipe PMMA waveguide. The attenuation loss of this pipe at 3.1THz was 9.65dB/m. Further more, bending loss of the pipe waveguides was investigated. The experimental result shows good transmission properties of the pipe.

Terahertz (THz) radiation is an under developing range in the electromagnetic spectrum. It has attracted a lot of attentions due to its various potential applications. However, THz systems are difficult to be integrated into a smart size due to the limitation of its long wavelength. In this presentation, we propose a new approach to design planar lenses with a thickness of several hundred nanometers in the THz range. The fabricated lenses are characterized with a focal plane imaging system and it is found that they can focus the THz light and image an object well. It is expected that this new approach can pave a way for smart THz systems integration.

In this paper, we will introduce a dual-THz-band SIS (Superconductor-Insulator-Superconductor) heterodyne radiometer system developed for the atmospheric profiling synthetic observation system project (APSOS). This THz system is intended to have a durable and compact design to meet the challenging requirements of remote operation. The system as well as its major components such as antenna tipping, quasi-optics, cryogenics, SIS mixers and FFTS backend will be discussed thoroughly. Some scientific simulation focusing on the atmospheric profiling components at THz bands will also be investigated.

This Paper introduces a 640×512 InGaAs focal plane array (FPA) camera integrated into a grating spectrometer for measuring 1.58μm absorption spectra of CO2. To gain atmospheric CO₂ concentration by detecting short wave infrared of reflective sunlight from the earth surface has been demonstrated to be an effective way. A hyperspectral spectrometer is designed to detect 1.58μm absorption spectra of CO₂. The spectrometer is a grating spectrometer which is optimised to respond to the spectral range from 1.562 ~ 1.592μ with spectral resolution of 0.1nm. For high sensitivity, F-number is determined to be 1.8. We designed a 640×512 InGaAs FPA camera system which can be coordinated with the grating spectrometer. The camera integrated a 640×512 InGaAs FPA with 25 μm pixel pitch. The 640×512 InGaAs FPA is sensitive to 0.9μm-to-1.7μm short wave infrared (SWIR) band and features a 298 K temperature detectivity, D^*, greater than 5×10¹² cm-1√Hz∕W. The 640×512 InGaAs FPA has characteristics of quantum efficiency no less than 70% at wavelength of 1.58 μm, pixel operability more than 99.91%, two gain modes and three integrat ion modes. The camera features 3Hz rate (exposure time) and 14-bit output. The FPA’s embedded TEC module is controlled to keep the detector core at proper temperature. The detector core temperature could be adjusted to below 263 K for lower readout noise and dark current. A Universal Series Buses 2.0 (USB2.0) has been used to transmit spectral data and commands. Commands of window size, position, gain mode and integration time per frame can be sent by the USB2.0 interface.

In the present article, silver cone antenna and its arrays are designed according to the requirement of wide bandwidth terahertz irradiation property. Coordinate transformation method is employed to analyze the solution process of the integrate equation of the irradiated electromagnetic field. And CST microwave studio software is employed to simulate the terahertz irradiation properties of Ag cone antenna arrays. Theoretical analysis and simulation results both manifest that the single Ag cone antenna with micrometer scale size can irradiate a wide bandwidth THz wave with the gain of 22.7dBi, while its corresponding antenna arrays with proper configuration can further improve the radiation pattern and enhance the gain to 42.5dBi. The theoretical analysis and CST simulation results will be useful for the guidance of experimental investigation of terahertz irradiation sources.

In this paper, we theoretically derive the local density of state (LDOS) in vacuum above a semi-infinite metamaterial. By using S-parameter retrieval methods, the obtained results of effective permittivity and permeability are employed to analyze the LDOS of metamaterial. It shows that p-polarization surface wave is the major contribution to near field radiation for electrical response, while s-polarization surface wave contributes most to near-field radiation for magnetic response. The study suggests a convenient way to control the enhanced near-field radiation.

Compare with width antenna beam system, a narrow beam system need a faster angle catching method. In this paper, three kinds of methods are introduced: the first one is the delay autocorrelation method; the second one is cross correlation method; the last one is cycle spectrum correlation method. All these three methods need no data demodulation, so they can output angle value quickly. They have different advantages and disadvantages, and are used in different condition. Delay autocorrelation method is fit for mono-channel and mono-pulse angle tracking system. The received signal pass a delayer, then correlate with itself. A notable advantage of the method is that it has a very simple structure. But its performance is not very good when SNR is very low. Cross correlation method is only fit for double-channel and mono-pulse angle tracking system .But it can improve the output accuracy, reduce the influence of noise. Spectrum correlation method has perfect performance. But it needs much more resource. This paper introduces theories and performance of these three methods, especially in high dynamic and low SNR condition .Then it points out how to select a method in different condition according to their characters.

This paper presents the design and characterization of a novel quasioptical subharmonically pumped GaAs Schottky diode mixer at 375 GHz. It features the use of two off-axis twin-slot antennas fed by CPW to receive the RF and LO signals respectively. The mixer circuits together with the antennas are integrated on a silicon extended elliptical lens. Conventional harmonic balance simulations in combination with 3D fullwave simulations in HFSS are carried out to analyze the performance of the mixer. Optimal conversion loss is obtained after impedances of the LO and RF ports are matched.Final simulation results show that the mixer achieves a DSB conversion loss of 10 dB and a noise temperature of 2900 K.

This paper presents a low power ADC for the 512*512 infrared focal plane arrays (IRFPA) readout integrated circuit(ROIC). The major structure, the working mode and the simulation result of the readout integrated circuit are shown in this paper. The power supply voltage of 0.35μm standard CMOS process is 3.3V in this design, and then the output range of the Direct Injection (DI) input circuit is reached 2V. Successive-approximation-register (SAR) ADC architecture is used in this readout integrated circuit. And each ADC is shared by one column of the IRFPA. This SAR ADC is made up of a 13-bit digital-analog converter (DAC), a high resolution comparator, and a digital control circuit. The most important part is the voltage-scaling and charge-scaling charge redistribution DAC. In this DAC, charge scaling with a capacitor ladder to determine the least significant bits is combined with voltage scaling with a resister ladder to determine the most significant bits. The comparator uses three-stage operational amplifier structure to get a 77dB differential gain. The Common-Mode input rang of the comparator is 1V to 3V, and minimum resolvable voltage difference is 0.3mV. This SAR ADC has some advantages, especially in low power and high speed. The simulation result shows that the resolution of the ADC is 12 bit and the conversion time of the ADC is 6.5μs, while the power of each ADC is as low as 300μW. Finally, this SAR ADC can satisfy the request of 512*512 IRFPAs ROIC with a 100Hz frame rate.

For argumentation of feasibility of LST (Land Surface Temperature) retrieval using 8-10 μm infrared band, this paper focuses on design of long-wave infrared band based on theory research. Basis of thermal infrared radiative transfer and atmospheric simulation, the paper analyses atmospheric effect on different long-wave infrared and obtain a preliminary selection of potential spectral channels. Several configurations of long-wave infrared spectral band were selected to perform in Split-Window algorithm and the relation of LST retrieval precision with error source was analyzed. Results indicate the scheme of LST retrieval using 8.0-9.0μm long-wave infrared is feasibility for needed retrieval precision.

April 8, 2012, the east region of Inner Mongolia out broke a strong sandstorm. Based on the analysis of the spectral characteristics of dust, cloud and surface, this paper propose a duststorm mask algorithm for the identification of dust coverage region by using three infrared channels of FY-3B. By utilizing diurnal variation of brightness temperature of dust aerosol, the bi-temporal thermal dust index was established to represent the intensity of duststorm. Through the analysis we found that BTDI has a high negative correlation with aerosol optical depth which can be used as an effective means to monitor the duststorm.

We present an enhanced scheme of polarization-sensitive THz-ABCD which can provide about twice broader bandwidth than the conventional method. In our experiment using a 26 fs laser pulse, compared with 0.3~40 THz in the conventional scheme, bandwidth coverage from 0.3 to 80 THz has been achieved in the resolution-enhanced scheme. It also should have to be noted the terahertz source may also restrict the detection bandwidth. Employing the polarizationsensitive technology, the polarization in time domain, as well as the field amplitude, can be achieved with just one single scan.

The quality of infrared imaging system was limited by the non-uniformity (NU) in the Infrared Focal Plane Array(IRFPA), especially in the uncooled infrared imaging system. Scene based non-uniformity correction (SBNUC) algorithms are widely concerned since they only need the readout infrared data captured by the imaging system during its normal operation. However, there still exists the problem of ghost artifact in the algorithms, and their performance is noticeably degraded when the methods are applied over scenes with lack of motion. In addition, most SBNUC algorithms are difficult to be implemented in the hardware. In this paper, to reduce the fringe NU in uncooled VOx IRFPA we present a simple and effective SBNUC method based on Constant Statistics in which the fringe NU is reduced by balancing the statistics of the vertical channels. Through analyzing the reason of ghost artifact being brought in in the SBNUC algorithms, our algorithm successfully reduce the ghost artifact that plagues SBNUC algorithms through the use of optimization techniques in the parameter estimation .The advantage of the algorithm lies in its simplicity and low computational complexity. Our algorithm is implemented on a FPGA hardware platform with XC5VSX50T as the kernel processor, the raw infrared data are provided by an uncooled infrared focal plane array of VOx which has fringe NU. Our processing system reaches high correction levels, fringe NU being reduced, the ghost artifact being decreased, which can lay a technical foundation for the following study and applications of high performance thermal imaging system.

In this study, the absorption spectra of native or thermal protein were measured in 0.2-1.4THz using terahertz time-domain spectroscopy (THz-TDS) system at room temperature, their absorption spectra and the refractive spectra were obtained. Experimental results indicate that protein both has strong absorption but their characteristics were not distinct in the THz region, and the absorption decreased during thermal denatured state. In order to prove protein had been denatured, we used Differential scanning calorimeter (DSC) measured their denatured temperature, from their DSC heating traces, collagen T^d=101℃, Bovine serum albumin T^d=97℃. While we also combined the Fourier transform infrared spectrometer (FTIR) to investigate their secondary and tertiary structure before and after denatuation, but the results did not have the distinct changes. We turned the absorption spectra and the refractive spectra to the dielectric spectra, and used the one-stage Debye model simulated the terahertz dielectric spectra of protein before and after denaturation. This research proved that the terahertz spectrum technology is feasible in testing protein that were affected by temperature or other factors，which can provide theoretical foundation in the further study about the THz spectrum of protein and peptide temperature stability.

Since the image of the moving target takes on sub-pixel attribute in the super-wide infrared staring warning system, the time correlation of the tareget track in the sequence images decreases, and it brings difficult to the correlation processing. Thus, the nearest correlation method is put forward firstly, and then the problem of track cross is solved through setting “false target” during the tracking course. The multi-life processing method, which synthetizes target information accumulation, single-pixel life, and average single-pixel continuance, is put forward to avoid the target’s emporary disappearance. This method solves the target time-domain response problem in the fisheye staring detection system. In this paper, some algorithms based on the sequence images are discussed aiming at the target track decision, , including target track register, target correlation processing, target elimination decision, target maintaining processing, and target start processing.

Fourier Transform Spectrometer (FTS), with its throughput, multiplex, and spectra resolution advantages, has become one of the most promising atmospheric remote-sensing instruments for the research on the global climax change and air quality evaluation. In this paper, the instrument concept and performances of a compact, portable, high resolution Fourier transform spectrometer, named B3M-FTS are reported. Sample atmospheric absorption spectra and corresponding retrieval results measured by the FTS are given. The success of atmospheric composition profile retrieval using the FTS measurements provides a useful way to understand the atmospheric chemistry, and validates the feasibility of atmospheric composition remote sensing using high resolution FTS.

The stable isotopes in atmospheric water vapor contain rich information on the hydrologic cycles and gaseous exchange processes between biosphere and atmosphere. About one-week field experiment was conducted to continuously measure the isotope composition of water vapor in ambient air using an open-path FTIR system. Mixing ratios of H₂ ¹⁶O and HD¹⁶O were measured simultaneously. Analysis of water vapor isotopes revealed that the variations of H₂ ¹⁶O and HD¹⁶O were highly related. Mixing ratios of both isotopes varied considerably on a daily timescale or between days, with no obvious diurnal cycle, whereas the deuterium isotopic [delta]D showed clear diel cycle. The results illustrated that the correlation between [delta]D and H₂O mixing ratio was relatively weak, which was also demonstrated by the Keeling plot analysis with the whole data. Yet the further Keeling analysis on a daily timescale displayed more obvious linear relationship between [delta]D and the total H₂O concentration. All daily isotopic values of evapotranspiration source were obtained, with the range between -113.93±10.25‰ and -245.63±17.61‰ over the observation period.

Compared with traditional microwave and millimeter wave radars, Terahertz radar has wide signal bandwidth and a very narrow antenna beam, which is beneficial to the realization of high resolution imaging. And as an instantaneous narrowband and synthetic wideband waveform, stepped frequency radar signal has been widely exploited in many applications, since it allows high range resolution with modest requirements of the system bandwidth. As an instantaneous narrowband and synthetic wideband waveform, stepped frequency radar signal has been widely exploited in many applications, since it allows high range resolution with modest requirements of the system bandwidth. This paper presents the design of a 0.2THz stepped frequency imaging radar system with operating bandwidth of 12 GHz, thus, a theoretical range resolution below 1.25 cm. The simulation of the system is implemented by using system design parameters. An experimental trial has been performed, and one-dimensional range profile of the stationary target is obtained by Imaging Experiment using THz radar. Results show that the THz radar imaging system could achieve the target detection and centimeter-level range resolution.

An optical refractive index sensor based on the Rayleigh anomaly of the gold grating is demonstrated in the terahertz (THz) wave band. A pronounced peak due to the Rayleigh anomaly of the gold grating is observed in the reflection spectrum, the center wavelength of which is sensitive to the environmental refractive index on the top of the grating. The wavelength of the Rayleigh anomaly reflection peak and the corresponding sensitivity are solely determined by the period of the gold grating, the larger the period, the longer the resonance wavelength and the higher the sensitivity. Therefore, a higher sensitivity can be achieved in the THz wave band. Both theoretical and experimental investigations show that the shape and intensity of the Rayleigh anomaly reflection peaks are determined by the duty cycle of the grating, for the value of the duty cycle about 0.4, the maximum intensity of the Rayleigh anomaly reflection peak was achieved.

Space based IR system uses the information of target LOS (line of sight) for target location. Recent researches show that the measuring precision of target LOS is usually determined by measuring precision of platform’s position and attitude, and deformation of sensor etc. Most methods for improving target location precision are either through improving platform’s position and attitude measuring precision or through calib rating the whole image obtained by IR sensor. With the development of measuring technology, it is harder to make a further improvement on the measuring precision of position and attitude of the platform and the expansion of the sensor view make calibrat ion of the whole image with a larger computation cost. In this paper, a method using control points to calibrate target LOS was proposed. Based on the analysis of the imaging process of the scanning sensor of space based IR system, this paper established a modify model of target LOS based on control points, used a bias filter to estimate the bias value of sensor boresight, and finally achieved the mission of target LOS calibrat ion. Different from the traditional calibration method of remote sensing image, the proposed method only made a correct ion on the LOS of suspicious target, but not established the accurate relationship between the all pixels and their real location, and has a similar calibration performance, but more lower computational complexity.

The terahertz transmission characteristics of bilayer metallic meshes are studied based on the finite difference time domain method. The bilayer well-shaped grid, the array of complementary square metallic pill and the cross wire-hole array were investigated. The results show that the bilayer well-shaped grid achieves a high-pass of filter function, while the bilayer array of complementary square metallic pill achieves a low-pass of filter function, the bilayer cross wire-hole array achieves a band-pass of filter function. Between two metallic microstructures, the medium need to be deposited. Obviously, medium thicknesses have an influence on the terahertz transmission characteristics of metallic microstructures. Simulation results show that with increasing the thicknesses of the medium the cut-off frequency of high-pass filter and low-pass filter move to low frequency. But the bilayer cross wire-hole array possesses two transmission peaks which display competition effect.

In order to improve the performance of a pulsed laser radar, methods based on wavelet filter and pulses accumulation are investigated. The transmitted pulses and received return waves are modeled for the simulation of signal processing through a filter. It shows that the modeled return waves could be denoised effectively with the wavelet biro3.9 or db9 if it is on the basis of compulsory denoising. However, under the condition of high fidelity requirement for the waveform, the signal-to-noise ratio may not be increased considerably. Thus, a new filter which is based on the combination of pulses accumulation and a followed wavelet transformer is proposed and studied. The results show that it is preferab

The relationship between correct discrimination probability of the human eye and perceivable signal-to-noise (SNR) threshold is studied for different equilateral triangle sizes with specified luminance through combining theoretical calculation with practical experiment based on triangle orientation discrimination (TOD) performance evaluation method. Specifically, the simulation images of triangle patterns are generated by an infrared imaging system (IRIS) simulation model. And the perceivable SNRs for these images are calculated by establishing the system theoretical model and the human vision system model. Meanwhile, the Four-Alternative Forced-Choice experiment is performed. Experiment results of several observers are averaged statistically and the curves of perceivable SNR threshold which change with the correct discrimination probability are obtained. Finally, the analyses of these results show that these changes are in accordance with the psychometric function and that the fitting curves become steep with the increase of triangle sizes. These data and conclusions are helpful to modify the existing TOD performance model of an IRIS.

In order to provide a guide for the design and optimization of bowtie-shaped antenna arrays, their plasmonic properties have been experimentally and numerically investigated with emphasis on geometry and gap separation in THz frequencies. A stronger absorption, frequent red-shift and a higher Q-factor were observed in bowtie dimers, instead of the monomers. Based on the finite-element (FE) simulations using CST Microwave Studio, it was found that these resonant properties of the periodic bowtie particles can be further modulated by their geometric factors, including aspect ratio, area porosity as well as gap separation.

We propose a low cost solution to generate power efficient ultra-wideband (UWB) radio frequency (RF) signal based on the hybrid of optical fiber and RF circuits. In our solution, any return-to-zero (RZ) optical pulse with enough bandwidth is transmitted over optical fiber first, then converted to a power-efficient UWB pulse by an electrical bandpass filter (EBPF) with a passband of 3.1-10.6 GHz. The transmission and modulation of UWB signal is processed in optical domain, whereas the generation of UWB is processed in electrical domain. This solution embodies the advantages of both low-loss long-haul transmission of optical fiber and low-cost mature RF circuits. Both UWB modulations of on-off keying (OOK) and binary phase shift keying (BPSK) are experimentally demonstrated. The impacts of RZ pulsewidth and the EBPF bandwidth on the UWB waveforms are also discussed.

Compared with the traditional infrared imaging technology, the new type of optical-readout uncooled infrared imaging technology based on MEMS has many advantages, such as low cost, small size, producing simple. In addition, the theory proves that the technology’s high thermal detection sensitivity. So it has a very broad application prospects in the field of high performance infrared detection. The paper mainly focuses on an image capturing and processing system in the new type of optical-readout uncooled infrared imaging technology based on MEMS. The image capturing and processing system consists of software and hardware. We build our image processing core hardware platform based on TI’s high performance DSP chip which is the TMS320DM642, and then design our image capturing board based on the MT9P031. MT9P031 is Micron’s company high frame rate, low power consumption CMOS chip. Last we use Intel’s company network transceiver devices-LXT971A to design the network output board. The software system is built on the real-time operating system DSP/BIOS. We design our video capture driver program based on TI's class–mini driver and network output program based on the NDK kit for image capturing and processing and transmitting. The experiment shows that the system has the advantages of high capturing resolution and fast processing speed. The speed of the network transmission is up to 100Mbps.

The uncooled optical readout infrared imaging system altering the infrared image directly into a visible image is becoming a hotspot of research recent years. How to reduce the volume and improve the quality of infrared imaging is a key problem of the optical readout infrared thermal imaging system. In this paper, an reflective readout method of infrared imaging systems is presented, by which reduce the volume of the system for about 30%, improve the uniformity of the infrared image, the minimum detectable angle can be decreased by 1.3×10^-5 deg than knife-edge filter method. The result of experiment is basically consistent with the theory analysis, experimental results indicate that the NETD of this system can be reach 173mK. Compared with traditional methods, the reflective optical readout method can effectively improve image quality.

High frequency readout-integrated circuit(ROIC) of 512×256 staring short wavelength(SW) infrared focal plane arrays(IRFPAs), focusing on high-frame rate output and noise suppression is implemented in this paper. The design of ROIC mentioned in it takes the previous version into account. The complete analog signal chain contains a novel input stage of capacitor feedback transimpedance amplifier(CTIA) preamplifier, a CDS (correlated double sampling) module, an amplifier of charge and complementary output stage. This ROIC is a full-custom flow integrated circuit design. The parasitic parameters are extracted once the layout is finished. Then the design is improved according to the result of post-layout simulation, which leads to the great improvements of the majority of parameters. The test and simulation results show that the output voltage range is 2.8V, the frame rate is 250Hz and the linearity within useful voltage range is above 99.1 percent, even when the temperature is 77K.

In this paper, an infrared and color image fusion algorithm based on luminance–contrast transfer technique is presented. This algorithm shall operate YCbCr transform on color visible image, and obtain the luminance component. Then, the grey-scale image fusion methods are utilized to fuse the luminance component of visible and infrared images to acquire grey-scale fusion image. After that, the grey-scale fusion image and visible image are fused to form color fusion image based on inversed YCbCr transform. To acquire better details appearance, a natural-sense color transfer fusion algorithm based on reference image is proposed. Furthermore, a real-time infrared/visible image fusion system based on FPGA is realized. Finally, this design and achievement is verified experimentally, and the experimental results show that the system can produce a color fusion image with good image quality and real-time performance.

Wavelength modulation spectroscopy has not yet formed an efficient method applied to measure line shape, which has restricted the development of tunable diode laser absorption spectroscopy. In the present paper, we have established a method which can recover line shape directly by using the data of the X and Y axes of odd harmonics based on the absorption spectral and harmonic theories. And then, in validating the accuracy of this method, the numerical simulation was used to recover the line shape of the transition at 6527.641cm^-1. Meanwhile, the experimental results show that the method established in this paper can recover the line shape accurately.

A terahertz polarizing beam splitter, based on a copper grating on polyimide (PI) substrate, was fabricated by the way of laser induced and non-electrolytic plating. The good polarization characteristics of the splitter in the range of 0°-180°polarization are verified experimentally using backward wave oscillator at fixed frequency of 300GHz, and the insertion losses of 0.13dB and 0.32dB are measured for the transmitted and reflected beams, respectively. The broadband transmission of TM wave of the splitter was also measured by terahertz time-domain spectroscopy, and the extinction ratio larger than 22dB is obtained in the frequency range of 0.2-1.5THz. The experiment results are in good agreement with finite element simulation results.

With the rapid development of space cameras and remote-sensing application technology, photoelectric sensor of the remote sensing satellite have evolved from the single-spectral, single type, single focal plane to the multi-spectral, multi-type, multi-focal plane integration direction. At present, the manufacturing process of the infrared detector has a larger improvement, but compared to the CCD device, the resolution is still low. In order to improve the resolution of infrared imaging systems, infrared imaging system using jointing multi-focal plane array can increase the resolution of infrared imaging systems. At present, remote sensing satellite equipped with a visible light detector and infrared detector, and design of multi-spectral, multi-type, multi-focal plane imaging circuit has become a new challenge. For multi-spectral, multi-, multi-focal plane imaging characteristics of the circuit system, this paper analysis and design of the FPGA signal processing circuit for multi-spectral, multi-focal plane jointing infrared imaging system, which includes time base correction circuit, infrared detector timing control circuit, multi-channel analog signal delay correction circuit, multi-channel uncertainty calibration circuit, average filtering of over-sampling circuit, multi-channel image data reading and correction circuit. Details the various parts of the design ideas and methods, design, simulation and testing. The test results show that the design is correct and feasible to meet the design requirements.

The high-frequency method for solving the Radar Cross Section (RCS) of Terahertz conductive targets in free space is presented in this paper. Consider the environment of free space, the free space physical optics integral equation is deduced by introducing the free space Green’s function into the Physical Optics (PO) method. Combined with the GRaphical-Electromagnetic COmputing (GRECO) method, the shadow regions are eliminated quickly and the geometry information is attained by reading the color and depths of each pixel. The RCS of Terahertz conductive targets can be exactly calculated in free space. The numerical results show that this method is efficient and accurate.

Fourier transform infrared spectrometer and THz-TDS were used to obtain the experimental spectrum of glycine below 600 cm^-1, and theoretical results of one or more zwitterionic glycine were calculated by DFT at the basis set of b31yp 6- 31+g(d,p) level based on Gaussian 03 software package in FIR region. There is more reasonable qualitative agreement between the calculated data of crystalline and observed line positions. Detailed assignments of the observed vibrational frequencies are discussed and the origins of some frequencies are analyzed by contrast. The low frequency collective mode of zwitterionic glycine is affected greatly by the intermolecular interaction and hydrogen-bonding effects and their vibrational modes are collective motion.

The three-step or many steps phase shifting method is usually employed to resolve the complex-conjugate ambiguity in Spectral-domain optical coherence tomography (SD-OCT). However it reduces the image quality and also the imaging speed is slow. In this paper two steps phase-shifting is used in digital image processing to resolve the complex-conjugate ambiguity and improves the quality of reconstructed image in SD-OCT. In the two-step phase shifting method the phase shifting operation is used only once which simplified the experiment and also the effect of relative error in SD-OCT on image quality is eliminated.

The operation and observation experience of users is affected by the quality of infrared images which are collected by infrared imager. And image quality is a significant indicator for the performance of image processing algorithm and the optimization of system parameters as well. An image quality reduced reference assessment model is put forward to evaluate the degree of infrared image quality reduction. The detail characteristic of infrared image texture is extracted by the fractal dimension analysis method proposed in this paper as the representation of image quality. The method computes the fractal dimension of every pixel one by one with a multi-scale window over the entire image to get the information of corresponding image block. A quality information image is mapped from the fractal dimension of all pixels to describe the infrared image quality. The parameters of the quality information image combined with the peak SNR of original infrared image are adopted as the metric of infrared image quality. The method can be embedded into image processing system to optimize image processing algorithms and parameters settings, and provide reference for fault diagnosis.

Pulsed-heating infrared thermography non-destructive testing is one of the most common used technology in industial NDT/NDE. It has an advantage on simple instrument and easy operation among method for NDT/NDE. To get an persuasive result, properties of heating pulse should be adjusted to testing condition, such as depth of defect and thermal conductivity of material. This paper tries to derive a method for optimization of heating pulse. The method is based on theory of thermal wave. The pulse should be chosen to make itself contain more effective thermal frequency components for NDT. The effect of this method can be verified by simulation and NDT experiments in this paper.

In reconstruction algorithms of CS, the ROMP algorithm is better than others, but, to obtain the better result, it's very important to estimate the sparsity of the image accurately. To solve this problem, an improved algorithm was proposed, in order to determine the best iterative number automatically, this algorithm determines whether the iterative number is the best or not by the previous result. Experimental result shows that the result of this improved algorithm is better than the result of the previous ROMP algorithm with deterministic iterative number.

Remote sensing infrared camera is two-dimensional thermal imaging equipment. In this paper, a new data acquiring and processing system of TDI infrared detector is given. This system is consisted of FPGA, ADC, SRAM memory, and so on. Low-pass filtering, pixel response non-uniformity correction, data synthesis and conversion of data output is implemented by a single FPGA. The SNR is improved by denoising algorithm based on oversample and comb filter. This system is easy to implement and can be applied in imaging device widely. The performance of imaging system is improved.

Step frequency signal is one of the more commonly used radar signal for high range resolution, it commonly used in radar target recognition. The wavelength of Terahertz signal is shorter than that of the microwave, so it is easy to realize the high range resolution. The paper first introduces the step frequency signal to obtain the one-dimensional distance image, and analyze the principle of high resolution range profiles of step frequency radar. Then, the 0.2THz step frequency radar systems are introduced. Finally, the high resolution range profiles are achieved by the simulation of Matlab. The simulation results show that the step frequency THz radar can reach centimeter level high resolution on stationary targets. For moving targets exist distance divergence and coupling shift. With greater speed, the greater the distortion.

In this paper, a novel 32×1 ROIC with high dynamic range is presented. The ROIC contains a capacitive transimpedance input amplifier (CTIA integrator), followed by a comparator that set a threshold voltage for comparing the integrating signal. It contains the time-to-threshold information in adding additional dynamic range with a linear voltage ramp input, in addition to the regular integration signal. By the end of integration, if the integration signal is less than the threshold voltage, the integration signal is sampled for readout. When the integrating signal is reached to the threshold voltage before the end of integration, the ramping voltage is stored and later sampled for readout in representing the signal level and a digital flag is set in recording the event of trigger. Thus, a high level signal can be saved before it saturating the integrator. A test chip of 32×1 ROIC is designed and fabricated with 0.35 μm triple metal, double poly CMOS technology. The chip test results prove correct function of the circuit with 3.3 V power supply. The results of tracing one channel show that the dynamic range increases 54 dB with a 10-bit ADC and the readout clock frequency is up to 10 MHz.

HgCdTe electrons initiated avalanche photodiodes (e-APDs) in linear multiplication mode can be used for high speed applications such as active imaging. A readout integrated circuit of e-APD FPA is designed for dual mode passive/active imaging system. Unit cell circuit architecture of ROIC includes a high voltage protection module, a Sample-Hold circuit module, a comparator, output driver stage and a integrator module which includes a amplifier and three capacitors. Generally, APD FPA works at reversed bias such as 5V-15V in active imaging mode, and pixels’ dark currents increase exponentially as the reverse-bias voltage is increased. Some cells of ROIC may be short to high voltage because of avalanche breakdown of diodes. If there is no protection circuit, the whole ROIC would be burnt out. Thus a protection circuit module introduced in every ROIC cell circuit is necessary to make sure the rest units of ROIC can still work. Conventional 5V CMOS process is applied to implement the high voltage protection with the small area other than LDMOS in high voltage BCD process in the limited 100μm×100μm pitch area. In integrator module, three integration capacitors are included in the ROIC to provide switchable well capacity. One of them can be shared in two modes in order to save area. Constraints such as pixel area and power lead us design toward a simple one-stage cascade operational transconductance amplifier (OTA) as pre-amplifier which can avoid potential instability caused by inaccuracy of MOSFET Model at 77K.