光学学报, 2012, 32 (12): 1204001, 网络出版: 2012-11-06
近红外线列探测器传递函数测试系统
Modulation Transfer Function Measurement of Near Infrared Linear Focal Plane Arrays
探测器 器件调制传递函数 近红外 狭缝法 detectors modulation transfer function of the device near infrared InGaAs InGaAs slit method
摘要
器件的调制传递函数(MTF)表征了光电成像器件对空间频率的对比度传递特性,可以全面地评价其成像性能。随着器件的发展,用MTF来评价器件越来越受到重视。针对近红外InGaAs焦平面器件MTF的测试需求,搭建了一套用狭缝法测试该波段线列器件MTF的系统。系统采用全反射式Offner光学结构将狭缝高质量地成像在待测器件上。成像光学结构由两块共轴的球面反射镜构成,11成像,F数为4;在芯片工作波长为1.7 μm时,在高达8 mm×30 mm的宽视场内,20 lp/mm(对应尺寸25 μm×25 μm的芯片特征频率)处的实测MTF高于0.8,接近衍射极限。利用该系统对8元InGaAs线列探测器进行MTF测试(标称光敏元尺寸为100 μm×100 μm),6次重复测试得到的MTF数据的标准偏差与均值之比,在截止频率10 lp/mm内小于2%,测量的相对不确定度小于4.7%。
Abstract
The modulation transfer function (MTF) of an electro-optical device describes the image quality in terms of contrast as a function of spatial frequency, which is a much better way to evaluate a device. With the development of electro-optical devices, MTF becomes a popular technique in device evaluation. A system to measure the MTF of near infrared InGaAs linear focal plane arrays is built and an all-reflective Offner relay is used to image the slit onto the measured device. The Offner relay consists of two coaxial spherical mirrors, operating as a 11 imager. At the working wavelength of 1.7 μm, the Offner relay shows a nearly diffraction limited performance over an 8 mm×30 mm field, and the measured MTF at 20 lp/mm is above 0.8 everywhere in the field. Using this system, the MTF of an 8×1 InGaAs linear focal plane array (FPA), of which the nominal pixel size is 100 μm×100 μm is successfully measured. The result shows that the ratio of the standard deviation to the average of 6 repeated tests is below 2% within the cutoff frequency of 10 lp/mm. The relative uncertainty of the MTF measurement of the 8×1 linear FPA is below 4.7%.
许中华, 方家熊. 近红外线列探测器传递函数测试系统[J]. 光学学报, 2012, 32(12): 1204001. Xu Zhonghua, Fang Jiaxiong. Modulation Transfer Function Measurement of Near Infrared Linear Focal Plane Arrays[J]. Acta Optica Sinica, 2012, 32(12): 1204001.