COL 12(4), 043001(2014) CHINESE OPTICS LETTERS April 10, 2014
High-throughput deconvolution-resolved computational
spectrometer
Jiang Yue (
), Jing Han (
), Yi Zhang (
üüü
), and Lianfa Bai (
ÝÝÝ
)
∗
School of Electronic Engineering and Optoelectronic Tec hnology, Nanjing University of
Science and Technology, Nanjing 210094, China
∗
Corresponding author: mrblf@163.com
Received November 28, 2013; accepted March 5, 2014; posted online April 4, 2014
A novel high-throughput spectrometer with a wide-slit is presented. In conventional spectrometers, the
slit limited the light throughput. Here, the slit is replaced with a much wider one (200 µm) to increase
throughput. A beam splitter is utilized to construct a dual-path optics to measure both non-dispersed
and dispersed light intensity which comes from the wide-slit. While the dispersed light intensit y is result
of the non-dispersed light convoluted spectrum of the source, the spectrum can be acquired by solving
the inverse problem of deconvolution. Experiments show that the reconstructed spectra achieved almost
the same resolution measured by traditional spectrometer, while throughput and peak signal-to-noise ratio
(PSNR) are improved dramatically.
OCIS codes: 300.6190, 100.6640, 100.3190.
doi: 10.3788/COL201412.043001.
High-throughput and high spectral resolution are es-
sential demands for spectrometers. Conventional slit-
based spectrometer requires the input slit should be
narrow to achieve a reasonable resolution, due to too
small slit cannot gather enough radiation. A number
of designs have been presented to address the demands.
Also a method could maximize the throughput with-
out sacrificing spectral resolution, we call it having the
Jacquinot advantage
[1]
.
Over past several decades, two most important ap-
proaches were proposed to improve the performance
of sp ectrometer. One is coded aperture spectrometer
(CAS) and the other is Fourier transform spectrometer
(FTS). CAS replaces the slit with a two dimensional
coded matrix aper ture, which is called a mask. And it
wa s introduced as a multi-slit spectrometer to increase
light throughput without loss of spectral resolution
[2]
.
After more than half century development, the major
CAS is Hadamard- transform spectrometers (HTS)
[3,4]
.
Most encoded a perture theories are based on Hadamard
matrices now. However, in recent years some new static,
multiplex CASs were proposed based on new mathemat-
ical models
[2,5]
. For a CAS, a better spectral resolution
lays on smaller mask features. Unfortunately, diffraction
and optical blur negate the advantages for the small mask
feature
[6]
. Apart from CAS, FTS is another method ex-
hibiting Jacquinot advantage, it records interference pat-
terns to estimate the spectrum of the incident light. But
a classic FTS usually containing mechanical scanning el-
ements prevents itself to be assembled easily, compactly
and cheaply. Hence, attempting on eliminating moving
parts to make a smaller, more reliable and inexpensive
system is studied in recent years
[7−9]
.
The key component of CAS is that it measures
weighted multiple spectral channels instead of a sin-
gle one for improving throughput and signal-to-noise
ratio (SNR). However, there were several critical draw-
backs caused by coded aperture. First of all, high preci-
sion and high resolution coded aperture is not available
now. Then, the system needs small mask feature to
achieve high spectral resolution, but it will bring un-
expected diffraction and optical blur. In this letter, a
novel high-throughput, spectral-channel-multiplied spec-
trometer without a spatial filter is presented, wherein
spectrum is reconstructed by solving an inverse problem
of deconvolution. The new design will achieve higher
resolution or longer spectral range without bringing any
aberration in by eliminating physical spatial modulator
such as a coded ap erture. Furthermore, the prop osed
system is stationary without any moving parts; and it is
not much sensitive to shake compared with FTS. Figure
1 shows a schematic of the deconvolution-resolved com-
putational spectrometer (DSCS).
In Fig. 1, there are two optical paths, both non-
dispersed and dispersed light intensity can be measured.
One path is based on a typical slit-based spectrometer,
which it is indicated as dispersed-branch. The other path
is called non-dispersed-branch. Based on this structure,
lights intensity measured by CCD 2nd is the result of
light intensity mea sured by CCD 1st convoluted spec-
trum of the light source. This relation is demonstrated
in following paragraphs.
The detail about the system is described as follows.
Light of the source is focused on a wide-slit (width of
200 μm) by objective lens (focal length (FL): 50 mm,
Fig. 1. (Color online) Schematic of the DSCS system.
1671-7694/2014/043001(4) 043001-1
c
2014 Chinese Optics Letters
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