In order to realize the high precision alignment of a catadioptric infrared optical system and improve the imaging quality of the system, a method of using visible light interferometer, infrared interferometer and articulated arm to align infrared optical system was proposed in this paper. First, the characteristics of the infrared optical system were introduced, and the alignment tolerances of each optical element were simulated and analyzed. Then, by aligning the R-C system of primary mirror assembly, the primary mirror assembly reference was extended to the mechanical mechanism, which provided the reference for subsequent precise alignment. The articulated arm was used to monitor the three-dimensional position of the lens assembly, in order to ensure the accuracy of the lens assembly initial alignment. Finally, the infrared interferometer was used to monitor the wavefront aberration of the system, and the relationship between the misalignment of the lens assembly and the zernike coefficient of the system was established, which could guide the alignment work, clear the direction of alignment, and finally realize the accurate alignment of the optical system. The experimental results indicated that the wavefront aberration values of the optical system were better than 1/15 λ (λ =3.39 μm), and each field amplitude transfer function(MTF) was better than 0.25, which met the requirements of imaging quality. It provided a feasible way for the catadioptric infrared optical system to be aligned, and also could be extended to the alignment of the remote sensors of similar structures space flight and aviation.
Diffractive optical system can be a favorable choice for large-aperture space telescope to reduce the mass and size of image system. To meet the demand of large-aperture, high efficiency, lightweight diffractive optic for high resolution remote sensing, a 200 mm diameter, 20 μmthick, 4-level diffractive membrane fabricated is shown to have over 62% diffraction efficiency into the +1 order, with 0.051 efficiency RMS. Over 66% diffraction efficiency is achieved for a 100 mm aperture membrane, with 0.023 efficiency RMS. The membrane thickness uniformity control is discussed and 8 nm wave front error RMS is achieved in 100 mm diameter.
This paper presents the impact of the light source expanded width on the detection sensitivity in an optical readout
uncooled infrared system, which consists of a focal-plane array (FPA) containing bi-material cantilever pixels and
reflectors. The relationship between the light source expanded width and the detection sensitivity is discussed based on
four different curvatures of reflectors(R=8mm,11mm,25mm,∞). The analysis indicates that the detection sensitivity
decreases with the light source expanded width's increment. For the flat reflectors , the detection sensitivity decreases to
90% when the light source expanded width is about 0.64mm. Compared with the flat ones, when the curvatures of
reflectors are smaller, the requirement of light source expanded width becomes lower for the sensitivity. The experiment
intuitively shows that the image quality by using the light source with 0.05mm size is better than the one with 1mm size,
which confirms the first conclusion.
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