Shortwave Infrared Imaging Spectrometer Research Articles

Methane remote sensing and emission quantification of offshore shallow water oil and gas platforms in the Gulf of Mexico

Offshore oil and natural gas platforms are responsible for about 30% of global oil and natural gas production. Despite the large share of global production there are few studies that have directly measured atmospheric methane emanating from these platforms. This study maps CH4 emissions from shallow water offshore oil and gas platforms with an imaging spectrometer by employing a method to capture the sun glint reflection from the water directly surrounding the target areas. We show how remote sensing with imaging spectrometers and glint targeting can be used to efficiently observe offshore infrastructure, quantify methane emissions, and attribute those emissions to specific infrastructure types. In 2021, the Global Airborne Observatory platform, which is an aircraft equipped with a visible shortwave infrared imaging spectrometer, surveyed over 150 offshore platforms and surrounding infrastructure in US federal and state waters in the Gulf of Mexico representing ∼8% of active shallow water infrastructure there. We find that CH4 emissions from the measured platforms exhibit highly skewed super emitter behavior. We find that these emissions mostly come from tanks and vent booms or stacks. We also find that the persistence and the loss rate from shallow water offshore infrastructure tends to be much higher than for typical onshore production.

Compact Shortwave Infrared Imaging Spectrometer Based on a Catadioptric Prism.

This article demonstrates a compact prism imaging spectrometer method. A catadioptric curved prism is located at the secondary mirror position of the spectrometer and used to balance the aberrations, enlarge the dispersion width, and decrease the volume. A mathematical model of the prism and spectrometer is derived, which provides an optimal initial structure for a non-coaxial spectrometer, simplifying the optical design process and reducing the system volume. Using this method, a compact shortwave infrared imaging spectrometer with a 16° field of view is designed with an F-number/3, and the measured spectrum ranges from 0.95 to 2.5 μm. The performance is analyzed and evaluated. Laboratory testing results prove the excellent optical performance, and under the same specifications, the spectrometer length decreases by 40%.

The discovery and extraction of Chinese ink characters from the wood surfaces of the Huangchangticou tomb of Western Han Dynasty

The traces of ancient characters were found from wooden block surfaces which was discovered from unearthed tomb called as “Huangchangticou” in Dingtao County, Shandong Province. The characters, which were written about 2000 years ago, were difficult to identify with the naked eye, as the wood surface has been contaminated and darkened due to efflorescence and mud stains, as well as exposure to oxygen and microorganisms. In this study, a ground-based shortwave infrared imaging spectrometer was used to detect these ink characters. Hyperspectral images with high spatial and spectral resolution were obtained from the wooden surfaces in a 1000–2500-nm band range. Combined with spectral analysis, the Chinese black ink characters were successfully extracted. More than 60 Chinese ink characters were found from the hidden surface of the two overlapped wood pieces. Interestingly, some mirror symmetry characters were also found on the face-to-face sides of the two pieces. The identification and interpretation of the characters provide insights into the specific date when they were written, as well as important archeological evidence to indicate such as the social status of the tomb’s owner, the time of construction, and manufacturing of segment for the royal family tomb in Han Dynasty.

Shortwave Infrared Imaging Spectroscopy for Analysis of Ancient Paintings.

Spectral analysis is one of the main non-destructive techniques used to examine cultural relics. Hyperspectral imaging technology, especially on the shortwave infrared (SWIR) band, can clearly extract information from paintings, such as color, pigment composition, damage characteristics, and painting techniques. All of these characteristics have significant scientific and practical value in the study of ancient paintings and other relics and in their protection and restoration. In this study, an ancient painting, numbered Gu-6541, which had been found in the Forbidden City, served as a sample. A ground-based SWIR imaging spectrometer was used to produce hyperspectral images with high spatial and spectral resolution. Results indicated that SWIR imaging spectral data greatly facilitates the extraction of line features used in drafting, even using a single band image. It can be used to identify and classify mineral pigments used in paintings. These images can detect alterations and traces of daub used in painting corrections and, combined with hyperspectral data analysis methods such as band combination or principal component analysis, such information can be extracted to highlight outcomes of interest. In brief, the SWIR imaging spectral technique was found to have a highly favorable effect on the extraction of line features from drawings and on the identification of colors, classification of paintings, and extraction of hidden information.

基于短波红外成像光谱仪的矿石光谱测量

基于短波红外成像光谱仪的矿石光谱测量

Design of short wave infrared imaging spectrometer system based on CDP.

A compact static infrared snapshot imaging spectrometer (ISIS) is designed in order to satisfy the application requirements of real-time spectral imaging for the moving targets. It consists of a CDP (crossed dispersion prism), an imaging lens, and a detector. Here we describe the spectral imaging principle, and design a short wave infrared imaging spectrometer with 4.8° field of view, the measured spectrum is from 0.9µm to 2.5µm and is sampled by 40 spectral channels. This instrument has a large potential for detecting, locating and identifying unknown energetic events in real-time.

High performance Czerny–Turner imaging spectrometer with aberrations corrected by tilted lenses

The design of the high performance imaging spectrometer using low-cost plane grating is researched in this paper. In order to correct the aberrations well, under the guidance of the vector aberration theory, the modification of Czerny–Turner system with inserted tilt lenses is proposed. The novel design of a short-wave infrared imaging spectrometer working at between wavelengths of 1–2.5μm is shown as an example, whose numerical aperture achieves 0.15 in image space. The aberrations are corrected well and the Modulation Transfer Function (MTF) performance is the same as the convex gratings systems. The smiles and keystones of the spectral image are acceptable. Advantages of the proposed design with a plane grating are obviously that the diffraction efficiency is high while the cost is very low.

短波红外棱镜-光栅-棱镜成像光谱仪光学系统设计

An optical system for short wave infrared imaging spectrometer was proposed based on prism-grating-prism(PGP)component.The system is composed by off-axis TMA,collimator,PGP and re-imaging lens,and its response covers the range 950 to 2 500 nm with a 22.5°field of view.The system is able to achieve wide field and broadband.By optimizing the PGP paramters and tilting the reimaging lens along the spectral dimenstion,keystone and smile became slight and were even less than 5 micrometer.Thus the obtained spectral data were more exact.

星载大视场短波红外成像光谱仪光学设计

Based on the requirements of shotwave infrared imaging spectrometer with wide field of view,considering the restrictive off-the-shelf detectors,a split field of view(FOV) method was developed.The principle of split field of view was analyzed.A spaceborne shortwave infrared imaging spectrometer with wide field of view was designed using the method.The imaging spectrometer are composed of a 11.42° telecentric off-axis three-mirror anastigmatic telescope and two offner convex grating spectral imaging system.Ray tracing,optimization and analyzing were performed by CODE V and ZEMAX software.The analyzed results demonstrate that the modulation transfer function for different spectral band is more than 0.7 which satisfies the pre-designed requirement.

短波红外成像光谱仪的景物辐射采集特性

短波红外成像光谱仪的景物辐射采集特性