Double-pass grating imaging spectrometer
Xin Meng (孟 鑫)
1
, Zhongming Yang (杨忠明)
2,
*, Jinyu Du (杜近宇)
3
,
and Guobin Fan (范国斌)
3
1
Science and Technology on Electronic Test & Measurement Laboratory, The 41st Research Institute of CETC,
Qingdao 266555, China
2
School of Information Science & Engineering and Shandong Provincial Key Laboratory of Laser Technology and
Application, Shandong University, Jinan 250100, China
3
Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, China
*Corresponding author: zhongming.yang@sdu.edu.cn
Received August 23, 2018; accepted November 22, 2018; posted online December 25, 2018
A double-pass grating imaging spectrometer is proposed and demonstrated. The traditional entrance slit is
replaced by a middle reflective slit, which is used as a spectral filter rather than a spatial filter. The light from
the scene passes through the same dispersive grating twice. The full image of the scene can be obtained with
a snapshot. Therefore, the stripe noise and image distortion caused by image mosaicking can be eliminated.
Besides, the target is easier to be captured and focused, just like using a camera. This method can be used
to obtain clearer spectral images of the scene conveniently and quickly.
OCIS codes: 120.6200, 110.4234, 300.6190, 120.4640.
doi: 10.3788/COL201917.011202.
A grating imaging spectrometer is a powerful tool to record
the spectral cube of the scene in visible and near-infrared
spectral bands. It has been widely used in laboratory and
industry, such as biotechnology and remote sensing
[1–4]
.In
order to improve system performance, methods with novel
designs for a grating imaging spectrometer have been pro-
posed to reduce aberrations in recent years
[5–9]
.
However, some problems caused by traditional work
mode still reduce the performance of the grating image
spectrometer. Traditionally, the spectral cube is first spa-
tially filtered by a slit. Then, a slice along the spectral
axis of the spectral cube is constructed by a dispersion
grating. So, the full image of the scene cannot be cap-
tured with a snapshot. As a result, additional equipment
is required to focus and observe the target scene, which
increases the complexity of the system. Besides, the
stripe noise and image distortion often appear to be
caused by traditional image mosaicking
[10]
. In addition,
the width of the slit is inversely proportional to the ra-
diation throughpu t, and at the same time, it is propor-
tional to the spatial resolution. These problems lead to
a contradiction between the radiation throughput and
the spatial resolution: the higher the former, the lower
the latter, and vice versa
[11]
.
A windowing push-broom hyperspectral imager has
been proposed by Couce et al.
[12]
. The full images of the
scene can be captured by adding a grating before the tradi-
tional imaging spectrometer. One grating is used for
dispersion modulation. The other is used for dispersion
demodulation. In order to capture high quality spectral
filtering images, the two gratings must have the same
specifications. At the same time, the incidence angles of
the two gratings must be the same. Otherwise, the spectral
filtering image captured by the camera is still distorted.
In this Letter, a double-pass grating imaging spectrom-
eter is proposed to eliminate distortion of spectral images.
The schematic of the proposed method is shown in
Fig.
1(a), which is used as a proving system. The system
is composed of a telescope, a beam splitter, a dispersive
grating, a reflective slit, and an imaging system. The dis-
persive grating and the reflective slit are used for the gen-
eration of an oblique slice of the spectral cube, which are
the key components. The imaging system is used to record
light intensity. The full image of the scene can be captured
with a snapshot, as shown in Fig.
1(b), followed by the
image captured by a traditional grating imaging spec-
trometer in Fig.
1(c). The spectrum mosaicking takes
Fig. 1. Schematic layout of the double-pass grating imaging
spectrometer. (a) Schematic of the present method; (b) simula-
tion of the captured image by the proposed method with a snap-
shot; (c) simulation of the captured image obtained by the
traditional grating imaging spectrometer with a snapshot.
COL 17(1), 011202(2019) CHINESE OPTICS LETTERS January 10, 2019
1671-7694/2019/011202(4) 011202-1 © 2019 Chinese Optics Letters