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.

To measure the global atmospheric three-dimensional distribution and change of temperature and humidity is one of the key areas in atmospheric remote sensing detection; it is also a new research and development direction in the field of meteorological satellite application. As a main element of China second generation of geostationary meteorological satellite Fengyun 4 (FY-4), which was launched on Dec. 11, 2016, the Geostationary Interferometric Infrared Sounder (GIIRS) is the first interferometric infrared sounder working on geostationary orbit internationally. It is used for vertical atmospheric sounding and gains atmospheric temperature, humidity, and disturbances. The combination of Fourier transform spectrometer technology and infrared detectors makes GIIRS have high spectral resolution and large coverage over spatial areas. With this kind of instrument, meteorological satellites can improve the capabilities for severe weather event monitoring and numerical weather prediction. Here a concise review of the GIIRS development project, including its history, missions and functions, technical design, key technologies, system integration, calibration and in-orbit operation status, etc., is presented.

Initiated by graphene, two-dimensional (2D) layered materials have attracted much attention owing to their novel layer-number-dependent physical and chemical properties. To fully utilize those properties, a fast and accurate determination of their layer number is the priority. Compared with conventional structural characterization tools, including atomic force microscopy, scanning electron microscopy, and transmission electron microscopy, the optical characterization methods such as optical contrast, Raman spectroscopy, photoluminescence, multiphoton imaging, and hyperspectral imaging have the distinctive advantages of a high-throughput and nondestructive examination. Here, taking the most studied 2D materials like graphene, MoS2, and black phosphorus as examples, we summarize the principles and applications of those optical characterization methods. The comparison of those methods may help us to select proper ones in a cost-effective way.