Method for Computing Kinoforms that Reduces Image Reconstruction Error

Gallagher, Neal C.; Liu, B.

doi:10.1364/ao.12.002328

Cited by 178 publications

(40 citation statements)

References 5 publications

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“…Holograms use diffraction to route the light to the bright areas of the reconstructed image. The complex relationship between the hologram (or kinoform) 79 and the reconstructed image is such that the image quality cannot be determined directly from the characteristics of the phase-modulating device as in the case for conventional displays. The hologram of the image is loaded on the phase-only LCOS device and illuminated by a collimated beam coming from a laser source.…”

Section: Algorithms Of Hologram Generation For Phase-only Lcos Devicementioning

confidence: 99%

Fundamentals of phase-only liquid crystal on silicon (LCOS) devices

2014

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This paper describes the fundamentals of phase-only liquid crystal on silicon (LCOS) technology, which have not been previously discussed in detail. This technology is widely utilized in high efficiency applications for real-time holography and diffractive optics. The paper begins with a brief introduction on the developmental trajectory of phase-only LCOS technology, followed by the correct selection of liquid crystal (LC) materials and corresponding electro-optic effects in such devices. Attention is focused on the essential requirements of the physical aspects of the LC layer as well as the indispensable parameters for the response time of the device. Furthermore, the basic functionalities embedded in the complementary metal oxide semiconductor (CMOS) silicon backplane for phase-only LCOS devices are illustrated, including two typical addressing schemes. Finally, the application of phase-only LCOS devices in real-time holography will be introduced in association with the use of cutting-edge computer-generated holograms. The architecture of LCOS devices is similar to conventional LC devices except that a silicon backplane constitutes one of the substrates (Figure 1). The silicon CMOS backplane consists of the electronic circuitry that is buried underneath pixel arrays to provide a high 'fill factor'. The pixels are aluminum mirrors deposited on the surface of the silicon backplane. The incident light is transmitted through the LC layer with almost zero absorption. The integration of high-performance driving circuitry allows the applied voltage to be changed on each pixel, thereby controlling the phase retardation of the incident wavefront across the device. Currently, there are two types of light modulation using LCOS devices, amplitude modulation and phase modulation. In the former case, the amplitude of the light signal is modulated 6,7 by varying the linear polarzation direction of the incident light passing through a linear polarizer, the same principle used in a standard LC television. In the latter case, the phase delay is accomplished by electrically adjusting the optical refractive index along the light path, which is possible because of the non-zero birefringence of the LC materials in use but should be carefully characterized. [8][9][10][11][12][13] In a phase-only LCOS SLM modulator, no light absorption by polarizers or other light-absorbing components will occur, such that the maximum light efficiency can be expected.Currently, most of the conventional LC devices are not able to efficiently modulate the phase of an incident wavefront. For instance, the LC device structure using thin film transistors is not suitable for phase modulation because an appropriate electro-optic effect has not been used (see the section on 'Twisted nematic (TN) configuration' and the section on 'VAN configuration' for details). Moreover, the pixels of this type of device are too large to provide acceptably large diffraction angles. In addition, the pixel circuitry and connection tracks are in the light path such that the ...

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Section: Algorithms Of Hologram Generation For Phase-only Lcos Devicementioning

confidence: 99%

Fundamentals of phase-only liquid crystal on silicon (LCOS) devices

2014

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“…[11][12][13][14][15] Direct pixel-by-pixel or point-by-point encoding can be a practical alternative. Several methods of encoding complex functions onto phase-only diffractive structures were developed shortly after the introduction of the kinoform.…”

Section: Relationship To Prior Kinoform Design Proceduresmentioning

confidence: 99%

Fully complex diffractive optics by means of patterned diffuser arrays: encoding concept and implications for fabrication

et al. 1997

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Arbitrary complex-valued functions can be implemented as arrays of individually specified diffusers. For any diffuser, only average step height and vertical roughness are needed to control phase and amplitude. This modulation concept suggests potentially low-cost fabrication methods in which desired topographies are patterned by exposing photoresist with partially developed speckle patterns. Analyses and experimental demonstrations that illustrate the modulation concept and aspects of the fabrication method are presented, with particular emphasis on limitations of complex recording set by various photoresist and exposure properties. Applications of diffuser array concepts to spatial light modulators and to gray-scale lithographic printing of micro-optics are also mentioned. © 1997 Optical Society of America [S0740-3232(97)

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“…Hence, nonlinear techniques of optimization have been developed for the synthesis of CGH's. Some of these techniques are projection onto constraint sets (POCS) [6], [7], [8], [9], error diffusion [lo], and direct binary search (DBS) [ l l ] .…”

Section: Introductionmentioning

confidence: 99%

Iterative interlacing approach for synthesis of computer-generated holograms

1992

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A new approach to optimizing computer-generated holograms (CGH's) is discussed. The approach can be summarized most generally as hierarchically designing a number of holograms to add up coherently to a single desired reconstruction. In the case of binary holograms, this approach results in the interlacing (IT) and the iterative interlacing (IIT) techniques. In the IT technique, a number of subholograms are designed and interlaced together to generate the total binary hologram. The first sttbhologram is designed to reconstruct the desired image. The succeeding subholograms are designed to correct the remaining error image. In the IIT technique, the remaining error image after the last subhologram is circulated back to the first subhologram, and the process is continued a number of sweeps until convergence. The IT and the IIT techniques can be used together with most CGH synthesis algorithms, and result in substantial reduction in reconstruction error as well as increased speed of convergence in the case of iterative algorithms.

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Method for Computing Kinoforms that Reduces Image Reconstruction Error

Cited by 178 publications

References 5 publications

Fundamentals of phase-only liquid crystal on silicon (LCOS) devices

Fundamentals of phase-only liquid crystal on silicon (LCOS) devices

Fully complex diffractive optics by means of patterned diffuser arrays: encoding concept and implications for fabrication

Iterative interlacing approach for synthesis of computer-generated holograms

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