This paper introduced a snapshot spectral polarization imaging system, compressive space-dimension dual-coded spectropolarimeter (CSDS). CSDS uses a digital micromirror device (DMD), a micro polarizer array detector (MPA) and a prism-grating-prism (PGP) to reconstruct a spectral linear Stocks 4D data cube with 100 channels and 3 Stocks vectors in a single shot. The reconstructed spectral profile is compared with the measurement results from micro-spectrometer (Ocean Optics STS-VIS). The feasibility and fidelity are verified from the image and spectral reconstruction evaluations. It is demonstrated that the target material can be distinguished by CSDS.
The polarization imaging detector combines polarization imaging with compressed sensing to obtain four polarization angles of information at the same time. By gaining information from a more dimensional dimension, this increases the contrast of the image and improves detection and recognition capabilities. However, the special structure of the polarization imaging detector reduces the imaging resolution. To solve this problem, we propose a combined imaging method that combines polarization imaging and compressed sensing. We compress the polarization information using digital micromirror array encoding, analyze the influence of the DMD on polarization image errors, and reconstruct the high-resolution polarization information image using deep learning networks. Compared to traditional compressed sensing reconstruction methods, our network achieves better reconstruction results and has higher peak signal-to-noise ratio (PSNR).
Aiming at the problems such as low efficiency of initial structure optimization design of traditional refractive optical system and overreliance on experience in structure selection. In this paper, an initial structure automatic optimization design method of refractive optical system based on deep learning is proposed. The structural characteristic data of the reference lens in the optical lens library are learned through supervised training. Unsupervised training model based on ray tracing is constructed to improve the generalization ability of deep neural network model. Through the network model generated by training, the optical system structure parameters including real glass are output, and the automatic optimal design of the initial structure of the refractive optical system is realized. The design results show that the initial structure spot radius of optical system in full field and full spectrum optimized by network model are close to the reference lens. The initial structure of the optical system can be designed according to different focal length requirements. The success rate of one million initial structures designed in this paper is greater than 96.403%, which indicates that the network model has good generalization ability. The method proposed in this paper contributes to automatically generate the initial structure of the refractive optical system rapidly and provides a new solution for the optimization of complex optical system.
Freeform surfaces are widely used in off-axis optical systems with large aperture, large field of view, and long focal length. The polarization effect caused by the non-rotationally symmetrical shape has an impact on the system's polarization imaging quality and measurement accuracy. Based on Jones’ notation, this paper proposes a polarization aberration analysis method for fringed Zernike polynomial freeform optical systems. It can solve the polarization effect problem introduced by the off-axis freeform surface optical system. This paper constructs a full-field polarisation aberration analysis model of non-rotationally symmetric freeform reflective optical systems. The role of the freeform surface on the polarization aberration distribution characteristics of non-rotationally symmetric optical systems is demonstrated. The multi-degree-of-freedom characteristic of the freeform surface makes the curvature of each point in the entrance pupil different, and the incident angle also changes slightly. The light propagation vector k is added on the basis of the two-dimensional ray tracing algorithm. By tracing the full-field polarized light of the off-axis optical system in the field of view, the Jones pupil diagram is obtained. The phase aberration, diattenuation and retardance are separated by Pauli decomposition and SVD decomposition. The theoretical relationship between the phase aberration and the freeform surface represented by the fringe Zernike polynomial is deduced. The distribution law of the diattenuation and retardance in the full aperture and full field of view is analyzed. The off-axis freeform surface optical system is designed. The analysis results show that the phase aberration of the off-axis freeform surface optical system is directly related to the surface shape of the freeform surface. The changes of the freeform surface to the diattenuation and retardance are both 56% of the diattenuation and retardance of the sistem. For deep-space telescopes and lithography systems, it is of great significance for improving system accuracy to master this change.
An engineering prototype of underwater wireless optical static monolithic communication system based on blue LED with high power and large field of view as communication light source and APD with high sensitivity and large target surface as receiving unit is established. The prototype adopts OOOK modulation mode, uses Fresnel lens with diameter of 75 mm and focal length of 25 mm as optical receiving antenna, installs narrowband filter, reduces signal-to-noise ratio, carries out communication coding through FPGA, and adopts staring direct detection mode to realize engineering integration of underwater wireless optical communication technology system, and intends to establish communication distance. The underwater large-field-of-view wireless optical communication link with a communication rate of 10 Mbit/s and a distance of 20 m. The performance parameters such as communication distance, power attenuation, communication delay, water disturbance and channel scattering of the system engineering prototype are measured and analyzed.
In order to realize the superresolution imaging with a telescope optical system, a two- dimensional polynomial function phase pupil filter with a high strehl ratio is designed, and its improvement for the light distribution around the focal point of the optical imaging system is demonstrated. The result of the theory analysis shows that, when the filter is added into the system, the system optical resolution is increased 1.33 times, and the strehl ratio is 0.75 time as much as that of the system without this pupil filter. The performance of two-dimensional polynomial filter is compared with the other typical phase pupil filters, including the three-zone, the four-zone and the one-dimensional polynomial phase filter. The comparison results show that the strehl ratio of the two-dimensional polynomial filter is the highest in these filters, and the transverse superresolution ratio of this filter is next only to that of the four-zone filter. But the strehl ratio of the four-zone filter is too low to be applied into the telescope.
Pupil off-axis optical system has the advantages of imaging unobscured and restraining the stray light for the next generation space telescope. However, non-rotationally asymmetric aberrations lead by the pupil off-axis structure becomes the main influencing factor of imaging quality. Since the freeform surface can provide more degrees of freedom for optical design, it is widely used to control the non-rotationally asymmetric aberrations. In order to guide designer optimize the pupil off-axis optical systems with freeform surfaces efficiently, an aberration analysis method for pupil off-axis optical system with Fringe Zernike polynomial freeform surfaces is proposed. The analysis expressions of third-order astigmatism and coma of the pupil off-axis freeform system are deduced. The freeform impacts on aberration nodal properties are analyzed. According to the aberration distribution, a pupil off-axis space telescope freeform optical system is designed by optimizing the Zernike terms pointedly. The effective focal length is 25m, the pupil diameter is 2m. By stitching multi-detectors to realize the field of view (FOV) of 1.2°×1.2°. Because of introducing freeform surfaces, the third-order astigmatism and coma nodes are both moved back to the FOV. Therefore, the asymmetric aberrations lead by pupil off-axis are balanced. The final imaging quality is closed to the diffraction limit, which meets the requirements.
In order to solve the evaluation problem of optical system under partially polarized light conditions caused by single ray tracing method, a full-field and full-pupil ray tracing method based on Stokes is proposed. The analytical relationship among the degrees of polarization (DOP) of the incident ray, the angle of the ray and the DOP of the emitting light is analyzed. The analysis results show that when the difference value between the incident angle and the refracted angle is less than 5.7°, the influence of the system on the DOP of the light can be reduced effectively. According to the space target polarization imaging requirements, a polarization imaging optical system with micro-polarizer array detector is designed. The resolution is 0.5m at the distance of 500km. Dynamic data exchange (DDE) is used to trace the full-field and full-pupil rays for the optimized optical system. Due to the DOP of any field of view can be calibrated, the polarization detecting accuracy of the optical system is improved. Therefore, the target can be recognized by matching the DOP of the incident ray and the DOP of any field of view.
Freeform surfaces have advantages on balancing asymmetric aberration of the unobscured push-broom imager. However, since the conventional paraxial aberration theory is no longer appropriate for the freeform system design, designers are lack of insights on the imaging quality from the freeform aberration distribution. In order to design the freeform optical system efficiently, the contribution and nodal behavior of coma and astigmatism introduced by Standard Zernike polynomial surface are discussed in detail. An unobscured three-mirror optical system with 850 mm effective focal length, 20°× 2° field of view (FOV) is designed. The coma and astigmatism nodal positions are moved into the real-FOV by selecting and optimizing the Zernike terms pointedly, which has balanced the off-axis asymmetric aberration. The results show that the modulation transfer function (MTF) is close to diffraction limit, and the distortion throughout full-FOV is less than 0.25%. At last, a computer-generated hologram (CGH) for freeform surface testing is designed. The CGH design error RMS is lower than λ/1000 at 632.8 nm, which meets the requirements for measurement.
With the development of laser transmission technology, the laser ranging and communication technology integration, miniaturization has become an important research direction nowadays. Based on laser ranging and communication integration of the requirements, design the1064nm fiber laser system, to suffice laser communication, laser ranging and beacon beam of the requirements at the same time could be provide the coherent detection to signal beam. The simulation experiment the 1064nm of free space optical communication in the laboratory, the coherent detection sensitivity is higher than -22dBm, the bit error rate 10−7 laser communication system. Multiple laser ranging to build coherent beam experimental realization of the coupling efficiency is higher than 70%, the laser output power of greater than 21W. The light source system is designed in this paper can realize the previous several lasers to complete the task, not only has the advantage of integration and miniaturization, through the simulation experiment could satisfy the communication requirements of power laser ranging ,and it is ideal light for laser transmission integration technology.
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