Crosstalk model of a deformable-mirror-based infrared scene projector

The goal of infrared (IR) scene projection is to provide realistic testing and evaluation of ihfrared-imaging sensors in a controlled laboratory environment. For a valid test, a dynamic spatial and temporal scene that accurately represents real-world targets over a specified wavelength band must be generated. Requirements for scene projection are determined by the sensor under test and can be broken down into several criteria: spatial resolution, dynamic range, contrast ratio, spectral distribution of in-band flux, frame rate, and spatial uniformity. ' The ultimate objective for IR scene projection is hardware-in-the-loop (HWIL) testing of thermal-imaging systems. In HWIL testing, an imaging IR seeker would be mounted on a computer-controlled gimbal and an IR scene generator/projector would present a realistic scene to the seeker, just as would appear in actual use.4'5 The main difficulty in IR scene projection lies in producing complex scenes of sufficient quality and complexity to characterize today' 5 high-performance IR systems. The Texas Instruments digital micromirror device6'° (TI DMD) has the potential to satisfy current requirements for IR scene projection when used as a spatial light modulator (SLM) for IR radiation from a thermal or laser source. The TI DMD consists of a matrix of discrete reflective elements that can independently tilt in response to an input video signal. A sketch of a portion of the DMD is shown in Fig. 1. Although the DMD can be operated in a bistable mode where the mirror pixels tilt at angles of + 10 and — 10 deg, in this paper, we describe the device as having an off state represented by an untilted pixel and an on state represented by a 10 deg pixel tilt. This particular mode of operation can be achieved by