Spectral resolution is one of the main indexes of the Carbon Dioxide Spectrometer and high resolution relies on the holographic diffraction grating.

Such optical grating should feature extremely high diffraction efficiency and surface precision to adapt to the space environment. Researchers started with basic experiments of a high precision exposure system and eventually manufactured an acceptable grating for flight testing.

A researcher opens the optical grating carefully and cleans the surface with an air brush, because even a tiny grain of dust could influence the detection results. [Photo/chinajilin.com.cn]

Signal to Noise Ratio (SNR) is another key index for the Carbon Dioxide Spectrometer. Researchers have to work in a lab kept at under - 5 degree Celsius to ensure minimal instrument noise and experimented in this low-temperature environment for months.

A researcher has a short rest on a small bed in the lab after a long experiment. [Photo/chinajilin.com.cn]