We present new imaging techniques based on computed restoration from holographic wavefront detection. This technique allows for unlimited resolution, optical and turbulent aberrations can be corrected. The relative movement of target and detector is computed and input to the image restoration algorithm. We discuss how this imagery can be extended to active referenceless holography or even to passive incoherent image.
With today’s organic photopolymer materials allowing high resolution, it is possible to record subwavelength volume holographic index gratings, i.e. index gratings with a period much smaller than the wavelength operating in the form birefringence regime. Such components are of interest for the direct view liquid crystal displays that suffer from a narrow viewing angle. In fact, by providing high birefringence, they compensate the intrinsic birefringence of the liquid crystal and thus, improve the viewing angle properties of the liquid crystal displays. Recently, we introduced a hybrid holographic compensator combining an “in plane” commercially available birefringent film and a slanted optical-axis subwavelength volume index grating recorded in a DuPont photopolymer. In this paper, we present the hybrid holographic compensation and its interesting features for TN-LCD viewing angle improvement. More particularly, a hybrid holographic compensator is designed for avionics application. It is based on a 120nm-period volume index gratings achieving an index modulation of 0.045 with a 33°-slant angle of the optical axis. The hybrid holographic compensator was manufactured and implemented on an avionics equipment from Thales Avionics. Visual inspection as well as contrast measurements showed a good improvement of the viewing angle characteristics.
Optical disc readout uses generally the "Central Aperture Readout" method. We show that "Push Pull Readout" can read efficiently very small phase modulation have good transparency and allow the stacking of many layers. We modified the push pull detection by adding a variable transparency in the far field that reduces the interlayer crosstalk, the system has potential for Terabyte capacity. We have realized a 8 layer DVD like optical disc and demonstrated that Push Pull Readout gives sufficient signal even on highly transparent disc.
Synthetic aperture is a way to overcome the spatial resolution limitation given by limited physical of an observation instrument. Active synthetic aperture techniques at optical wavelengths are presented. We show that 2D arrays of detectors overcome the co-phasing problem of the sub-pupils provided there is an overlap between each acquisition. This technique was applied to short range imaging at 633nm in laboratory environment, yielding to diffraction limited pupils 16 times larger than the original pupil without external measurement of the pupil phase history.
The key point to widen the veiwing angle of a TN-LCD is to realize a birefringent film with its optical axis tiled with respect to the display plane. We performed a negative tilted uniaxial film with holographically recorded volume index gratings in the form birefringence regime and studied the characteristics of such compensator in terms of viewing angle of a TN-LCD.
With over 100 million units per year, the optical pick up is probably the most widely produced electro optic assembly on these days. It is also the driving force of semiconductor laser production with development of higher power for high data rate recording and shorter wavelength for high density. The production of CD pick up is of course highly cost driven; over 20 years of optical storage history and ten years of CD, the reduction in size, power consumption and cost can be compared to the evolution of integrated circuit. Diffractive optics plays a significant role in this roadmap, although as will be seen not all functions can be expected to be played by diffractive optics. Refractive lens will remain the leading technology for all functions that involve strong bending of the rays. In the near future the production of CD and CD-ROM player is expected to reach a plateau at twice today's production but MO drives and soon DVD are taking off.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.