Electro-optic and infrared imaging sensors, such as CCD cameras and focal plane arrays, are of growing importance for a wide-range of military and commercial applications.
As the prevalence of these sensitive devices increases, so does the need for calibration and test instrumentation. Laboratory simulation enables realistic testing of sensors and associated algorithms without costly field tests. To provide accurate calibration and testing, simulation of realistic scenes requires projectors with enough fidelity that the sensor cannot distinguish the simulation from the natural environment. This type of high-fidelity projection is possible through the use of spatial light modulators (SLMs), which can control light spatially, spectrally, and in polarization.
Boulder Nonlinear Systems (BNS) is experienced in developing these advanced scene projectors using liquid crystal on silicon (LCoS) SLM technology for a variety of applications. LCoS SLM technology offers a low-cost, high-resolution alternative to resistive emitter and deformable mirror devices. Furthermore, by utilizing analog control of nematic liquid crystal modulators, BNS can provide true grayscale modulation without flickering. To date, BNS has developed spatial, spectral, and/or polarization modulating scene projectors for clients such as NASA, NIST, and NOAA.
In one recent example, BNS developed a polarization-modulating hyperspectral image projector capable of pixel-level control of the linear polarization state and intensity across the visible spectrum. Such devices can be used to provide accurate and repeatable calibration standards for advanced imaging sensor systems, resulting in decreased development costs and time while increasing the confidence in the successful final sensor deployment.
BNS is currently developing a new high-voltage 512 × 512 pixel SLM backplane that is designed to improve fabrication yield, increase display uniformity, and reduce addressing time to decrease amplitude ripple and take advantage of the 200 fps drivers recently developed by BNS (now licensed for commercial SLM sales by Meadowlark Optics). These advances will lead to further increases in simulated scene fidelity and provide the speed necessary for testing faster sensors.
|Left: Example of a spatially modulated simulation image from a 512 × 512 pixel scene projector. Center and Right: Examples of pixel-level polarization modulation in a polarization-modulating hyperspectral image projector. This system demonstrated a 550 Hz single band frame rate with 512 spectral bins and pixel-level polarization control across 4000 azimuthal polarization states.|