Light detection and ranging (LiDAR) return signal generation technology applied in the LiDAR indoor test and simulation is significant to design, develop, test, and validate a LiDAR’s capability and performance. To generate a target’s information carried by the return signal, the dimensional decomposition and equivalent generation method of the LiDAR return signal are proposed. The target four-dimensional (4D) information is decomposed into one-dimensional (1D) intensity information, 1D range information, and two-dimensional (2D) angle–angle spatial information. The 1D intensity information is simulated by the absorption of prism pairs, while the 1D range information is simulated by the combination of electrical and optical time delay. The 2D angle–angle spatial information is implemented by the stack of segmented digital mirror array device slice images in sequence. Moreover, a LiDAR return scene projector (LRSP) prototype is developed and its performance is measured. The results show that its energy dynamic range is 51.25 dB. The distance simulation range is 240.15 m to 22.5 km (1.601 to 150 μs). The simulation accuracy of the target’s depth is <9 cm (0.6 ns). The spatial resolution of 64 × 64 pixels is verified by vertical and horizontal line pairs test. Because the LRSP has 12 image slices, its resolution is 64 × 64 × 12 pixels in three-dimensional (3D) space. Finally, the prototype is demonstrated by reconstructing a staircase. The energy dynamic and 2D angle-angle spatial resolution are improved significantly compared with the existing LRSPs.
Dynamic infrared scene projection is a technology for converting infrared (IR) digital image sequences into IR radiating image sequences. One of the most promising technologies is light down-conversion technology based on photoinduced opaque (PIO) effect. A parametric end-to-end steady-state model was proposed to describe the PIO mechanism. It consisted of three submodels such as the silicon parameter model, the photoinduced free carrier model, and the constitutive relation model. Furthermore, the parametric full-link from pump photons’ power density, photoinduced free carrier concentration, complex dielectric constant, and complex refractive index to the emissivity was constructed and mathematically analyzed by the above model. In order to verify the model, an intrinsic silicon wafer was pumped by a continuous-wave running Nd:YAG laser when the wafer was heated up to 321, 423, 459, and 498 K, respectively. Correspondingly, the emissivity integrated from 3 to 5 μm, with the increase of the pump power density measured by an IR camera. The measurement result agreed well with the theoretical result computed by the parametric end-to-end steady-state model. The maximum apparent temperature of the region illuminated by the laser with a pump power density of 407 W cm − 2 is up to 453 K when the silicon wafer was kept at 498 K. At the same time, the background temperature was elevated to 330 K owing to the initial free-carrier absorption enhancement.
With the development of infrared imaging detection technology, it is not enough to recognize valuable target information quickly and accurately in complex environment simply by energy and graphics. Modern infrared imaging detection and recognition systems have begun to make use of more physical features, such as dynamic or static differences of spectral energy distribution in one or more work bands, to improve the target recognition and anti-jamming ability of infrared imaging systems. Distinguishing differences in physical characteristics of objects, backgrounds or disturbances from time, space, spectrum and energy dimensions is becoming a main direction of development of IR imaging detection technology. In an effort to improve technology for performance testing and hardware-in-the-loop (HWIL) simulation of multi-spectral imagers, we have been developing a wide-band infrared spectral engine based on spatial light modulator (SLM). The wide-band infrared spectral engine is comprised of a blackbody IR source, a Digital Micromirror Device (DMD) and some optical components, and it is capable of generating the spectral distributions with programming each of the DMD’s spatial pixels. The problem of mismatch between the unit-under-test (UUT) spectral and the infrared image projector spectral in the HWIL simulation can be resolved in this way. A prototype of the wind-band infrared spectral engine has been designed and developed. A brief summary of previous work will be presented with a more detailed discussion of the recent test of the prototype. By using spectrometer, moving guide and some other devices, a set of test equipment has been built. And thought some stripe test patterns with different spatial frequencies, the key performance of the wide-band infrared spectral engine prototype has been tested. It was found that the waveband of the wind-band infrared spectral engine prototype is from 3 μm to 5μm, while the spectral control accuracy of the wavelength is less than 100 nm.