Multiscale Snapshot Imaging Spectrometer with
Large FOV and Fast Speed
Yiqun Ji
1, 2
, Jose Sasian,
2
, Yuheng Chen
1
, and Jiankang Zhou
1
1
Institute of Modern Optical Technologies, Key Lab of Advanced Optical Manufac turing Technologies of Jiangsu Province,
Key Lab of Modern Optical Technologies of Education Ministry of China,
A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), Soochow
University, No.1 Shizi Street, Suzhou, Jiangsu, PR China, 215006;
2
College of Optical Science Center, University of Arizona, 1630 East University Blvd., Tucson, Arizona, USA, 85721
ABSTRACT
A novel snapshot imaging spectrometer with large field-of-view (FOV) up to 100° is achieved by taking the
advantages of a multiscale fore-optics and a compact Offner imaging spectrograph. Based on the diffraction imaging
theory, the multiscale fore-optics composed of a monocentric spherical lens and multi-channel microlens array is
designed, over which panchromatic images with small FOV are of uniform image quality. And identical imaging
spectrographs with a dimension less than 30 cubic millimeters and with a high spectral resolution of about 2nm are
designed correspondingly. The presented imaging spectrometer works at the visible wavelength range which is from
400nm to 780nm. It is of a fast speed about F/2.4 and a compact configuration of only 200mm×300mm×300mm in
dimension. But the smile and keystone distortions are negligible.
Key Words: optical design, snapshot imaging spectrometer, multiscale, high speed, large field-of-view
1. INTRODUCTION
Imaging spectrometer with a convex diffraction grating aroused worldwide interests for its inherent advantages
[1-3]. The Offner type imaging spectrometer with unique ability of well correction of residual aberrations is a typical
represent [4, 5]. To achieve spectral images without overlap, an entrance slit is designed as its field stop, which limits the
field-of-view (FOV) and the etendue that eventually degrades the spectral resolution. And to overcome this disadvantage,
push broom imaging mode is usually adopted. But another problem appears that the spectral images are obtained
non-simultaneously, and the adjacent spectral images are with time delay.
In this paper, based on the diffraction imaging theory [6, 7] and spectral imaging system designs [8~10], a new
system which is able to obtain snapshot spectral images of a large FOV up to 100° without deteriorating the advantages
of the convex grating based Offner type imaging spectrometer is designed. Its fore optics is designed concentric and with
multi imaging channels to realize compact structure and obtain good performance. And the spectrographs are designed
with multi-channel to match it. The fore optics is designed composed of a mono-centric spherical lens and a micro-lens
array. The mono-centric lens has the advantages of obtaining FOV as large as needed, and is easy to obtain an
intermediate image with uniform residual aberration, which greatly simplifies the design of the micro-lens array. A series
of panchromatic sub-images are obtained after elaborate residual aberration correction by the micro-lens array. And each
panchromatic sub-image is then reimaged to a corresponding Offner type micro spectrograph. Each imaging channel
acquires the spectral images of a subfield. And those of the whole field needs post processing. To the single micro
Proc. of SPIE Vol. 9299 92990G-1