Kipp Andon Bauchert

Advances in liquid crystal spatial light modulators

Recent advances in our high-speed analog liquid crystal spatial light modulators (SLMs) will be presented. These advancements include higher pixel density, smaller pixel pitch, greatly improved optical efficiency, and higher speed operation. The new VLSI SLMs can utilize ferroelectric liquid crystal (FLC) or nematic liquid crystal (NLC) to achieve phase-only, amplitude-only and phase-amplitude-coupled modulation. These devices have applications in optical processing, optical storage, holographic display and beamsteering. Design criteria and experimental data will be presented.

Complex phase/amplitude spatial light modulator advances and use in a multispectral optical correlator

Optical processing systems often require compact high frame rate spatial light modulators (SLMs), usually with application specific modulation requirements in the complex plane. In this paper we discuss several advances at Boulder Nonlinear Systems toward this goal, including our liquid crystal (LC) on VLSI 128 X 128 analog SLM, and our multispectral hybrid incoherent to coherent converter.We also present the analysis of optical modulation possibilities when utilizing zero twist nematic and planar aligned chiral smectic LC on a reflective backplane. Finally we present the design of a multispectral optical correlator for machine vision applications such as food inspection, security, or manufacturing inspection.

Sampling technique for achieving full unit-circle coverage using a real-axis spatial light modulator

We investigate the possibility of using a real-axis spatial light modulator (SLM) to realize complex-amplitude modulation with full coverage over the unit circle. The real-axis SLM produces a pixelated bipolar-amplitude wavefront. Each pixel is basically a spatial pulse width with the signal information being carried by the pulses amplitude. Data streams generated in this manner have real and imaginary components due to the relative even and odd symmetry of the pulse amplitude modulation. When the pulse rate is twice the minimum Nyquist rate for band-limited amplitude modulation, it is possible to resolve the signal into its quadrature phase components (real and imaginary terms). By changing the relative amplitude of these quadrature phase terms, any value within the complex plane is accessible. Since the SLM does not have any optical gain, coverage is limited to the unit circle in the complex plane.

High-speed multilevel 512x512 spatial light modulator

Recent advances in our high-speed multi-level (analog) 512 X 512 liquid crystal spatial light modulator (SLM) will be presented. These advancements include smaller pixel pitch, greatly improved optical efficiency, and higher speed operation. The new VLSI SLM can utilize Ferroelectric Liquid Crystal to Nematic Liquid Crystal to achieve phase-only, amplitude-only, and phase-amplitude-coupled modulation. This device has applications in optical processing, optical storage, holographic display, and beam steering. Design criteria and experimental data will be presented.

Data-flow architecture for high-speed optical processors

For optical processor applications outside of laboratory experiments, it is desirable to streamline the data flow in order to obtain the highest possible throughput from the system. This paper presents the data flow architectures for two optical processors designed and built by Boulder Nonlinear Systems, as well as the processor designs and some experimental data.

Real-time hardware implementation of an optical correlation image preprocessing algorithm using an off-the-shelf image processing board

In general, the output data format of a sensor is not compatible with most programmable spatial light modulators (SLMs) used in optical correlators. Therefore, to use the sensor image as the input image in an optical correlator utilizing a programmable SLM, the image must be transformed or preprocessed. Another reason for preprocessing an image is the inherent edge detection of a binary phase-only filter (BPOF) or a ternary phase-amplitude filter (TPAF). The appropriate preprocessing algorithm can be used to enhance the edges in the input image. To be fully useful in an optical correlator system this preprocessing algorithm should be implementable at throughput rates equal to or greater than the throughput of the sensor. This paper presents the methodology and results of implementing some example preprocessing algorithms in an off-the-shelf image processing board to obtain video frame rates when interfacing to an RS-170 sensor.

Development of large-array spatial light modulators

Newer silicon foundry processes make possible high-resolution backplanes (i.e. larger arrays with more line pairs per millimeter). Higher resolution is a benefit of the small geometry processes being developed for the electronics industry. Unfortunately, the trend is to shrink the circuits and decrease the operating voltage of the chip. For liquid crystal on silicon (LCoS) devices, the loss in voltage has a negative impact on performance. Higher voltage provides the excitation to achieve good response time with sufficient modulation depth from liquid crystal electro-optic modulators. This paper discusses the development of large array devices using the smaller geometry processes and some of the techniques used to retain good performance from the liquid crystal modulators.

Liquid crystal on silicon spatial light modulator for infrared scene generation

Liquid crystal spatial light modulators are emerging as a viable alternative to emitter arrays as the display engine for infrared scene projection. Some benefits of liquid crystal spatial light modulators include low cost, light weight (to enable portable test engines) flickerless scene generation with no dead pixels. Other possible advantages include high efficiency operation, scalable architecture and potential for high apparent temperature simulation. We discuss a recently developed high voltage 512x512 liquid crystal on silicon spatial light modulator. Design considerations and experimental data on device performance are presented.

High-speed multilevel phase/amplitude spatial light modulator advances

Recent and near-term advancements in our multi-level (analog) phase/amplitude liquid crystal spatial light modulators will be presented. These advancements include higher resolution, smaller pixel pitch, planarized pixel pads, and higher speed modulation for phase-only, amplitude-only, and phase- amplitude-coupled modulation. These devices have applications in optical processing, optical storage, holographic display, and beam steering. Design criteria and experimental data will be presented.

Optical correlation algorithm development for the Transfer of Optical Processing to Systems program

Optical correlation algorithms are being developed for implementation in the System for Passive Optical Target Recognition (SPOTR). These algorithms include preprocessing the input imagery for input into the spatial light modulator (SLM), smart filter development for recognizing an M60A2 tank at various elevations, azimuths and ranges, post-processing the output correlation plane to determine its validity, and filter management for efficient implementation of the smart filters.