Infrared detectors are being developed for high resolution and small pixels.To detect small pixels,an infrared optical system must have a small F-number.Therefore,based on the demand for small-pixel detection,this study designed an off-axis three-reflection infrared optical system with an F-number close to 1 using a Cook-type off-axis three-reflection structure.The primary,secondary,and tertiary mirrors of this optical system were all aspherical,with an F-number of 1.3,focal length of 60 mm,field of view of 1.6º×2.4º,and a wavelength band of 1.1-2.5 μm.The modulation transfer function(MTF)of this infrared optical system design was greater than 0.6 at a spatial cutoff frequency of 100 line pairs per millimeter.The RMS value of the diffuse spot was smaller than the pixel size of the detector,with a distortion of less than 2%.The system design and simulation results indicated that the MTF of each field of view was close to the diffraction limit,meeting both imaging quality and small-pixel detection requirements.
small F-numberoff-axis three-mirroraspheric surfaceoptical design
万方数据
维普
