The optical design of an integral field spectrometer for far-infrared observations, the Far-Infrared Field-Imaging Line Spectrometer (FIFI LS), is presented. The instrument will fly on board the joint NASA/DLR airborne observatory SOFIA, observing in two nearly independent wavelength channels simultaneously: a blue channel (40-105 μm) and a red channel (105-210 μm). To achieve instantaneous integral field spectro-scopy for the first time in the far-infrared, a novel reflective image slicer system is utilized that slices the 5 x 5 pixel, two-dimensional field of view into a pseudo-long slit of 25 x 1 pixels. The slicer assembly consists of three sets of five mirrors that have optical power, enabling a compact design. After the sky field has been optically rearranged to the pseudoslit, the image is spectrally dispersed in a standard Littrow-mounted reflective grating spectrometer. The practical concerns for the optical design in the far-infrared and, in particular, the significant effect of diffraction in the entire optical system is discussed.
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机译:介绍了用于远红外观测的积分场光谱仪的光学设计,即远红外场成像线光谱仪(FIFI LS)。该仪器将飞行在NASA / DLR联合空中观测站SOFIA上,同时在两个几乎独立的波长通道中进行观测:一个蓝色通道(40-105μm)和一个红色通道(105-210μm)。为了在远红外领域首次实现瞬时积分场光谱,采用了一种新颖的反射式图像切片器系统,该系统将5 x 5像素的二维视场切成25 x 1的伪长缝像素。切片器组件包括三组,每组五个具有光焦度的镜,可实现紧凑的设计。在将天空场光学重新排列为伪缝之后,图像会在标准的安装在Littrow上的反射光栅光谱仪中进行光谱分散。讨论了远红外光学设计的实际问题,尤其是整个光学系统中衍射的显着影响。
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