In order to test 2-color infrared sensors, a coupled infrared simulation system can generate radiometric outputs with wavelengths that range from less than 3 microns to more than 12 microns. There are two channels in the coupled simulation system, optically combined by a diachronic beam combiner. Each channel has an infrared blackbody, a filter, a diaphragm, and diaphragm-motors. The system is projected to the sensor under testing by a collimator. This makes it difficult to calibrate the system with only one-band thermal imager. Errors will be caused in the radiance levels measured by the narrow band thermal imager. This paper describes colorimetric temperature measurement techniques that have been developed to perform radiometric calibrations of these infrared simulation systems above. The calibration system consists of two infrared thermal imagers; one is operated at the wavelength range of MW-IR, and the other at the range of LW-IR.
The first and most essential capability a visible scene projection system must have is low background and high contrast during dynamic simulation. A complex visible scene projection system was developed to meet the above requirements. The complex visible scene projection system mainly consists of the optical fiber subsystem, LCD (Liquid Crystal Display) subsystem, multiple focal plane coupler and the collimation objective. The design and build and details of the system characterization of a prototype complex visible scene projector were summarized.
In the process of high-resolution astronomical observation and space optical mapping, the wavefront aberrations caused by atmosphere turbulence effect lead to reduced resolution of optical imaging sensor. Firstly, on the base of influence of atmosphere turbulence effect for the optical observation system, this paper investigates and analyses the development and technical characteristics of deformable mirror, which is the key device of optical wavefront control technology. In this part, the paper describes the basic principles of wavefront control and measurement using the current production line of deformable mirror, including micro-electromechanical systems (MEMS) deformable mirror which is one of the most promising technology for wavefront modulation and Shack-Hartmann wavefront sensors. Secondly, a new method based on the technology of optical wavefront control and the data of optical path difference (OPD) for simulating the effect of optical transmission induced by turbulence is presented in this paper. The modeling and characteristics of atmosphere turbulence effect applied for optical imagery detector of astronomical observation and space optical mapping has been obtained. Finally, based on the theory model of atmosphere turbulence effects and digital simulation results, a preliminary experiment was done and the results verify the feasibility of the new method. The OPD data corresponding to optical propagation effect through turbulent atmosphere can be achieved by the calculation based on the method of ray-tracing and principle of physical optics. It is a common practice to decompose aberrated wavefronts in series over the Zernike polynomials. These data will be applied to the drive and control of the deformable mirror. This kind of simulation method can be applied to simulate the optical distortions effect, such as the dithering and excursion of light spot, in the space based earth observation with the influence of turbulent atmosphere. With the help of the optical wavefront control technology, the optical sensor and ability of space optical detection system for correcting the target image blurred by turbulence of atmosphere can be tested and evaluated in the laboratory.
The multitarget compounding technique is key in an infrared hardware-in-the-loop simulation system. In this study, the beam-broadening theory and carefully designed experiments are presented to analyze a multitarget compounding system based on a dimpled mirror. By paraxial approximation of geometrical optics, the expression of broadened beamwidth of a dimpled-mirror two-mirror three-reflection concentric system was obtained as the function of system parameters. A multitarget compounding setup was designed and experiments were performed. Excellent matching results were achieved between the beamwidth theory and the experiments. Experimental results demonstrated that the beam-broadening theory is creditable and suitable to design the multitarget compounding system. The theory and experiments are beneficial to the future development and implementation of multitarget compounding technique.