In a study published in Optics Express, a research group led by Prof. LI Xiaotian from the Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) of the Chinese Academy of Sciences (CAS) proposed a cross-dispersed spatial heterodyne spectrometer (CDSHS).

The proposed spectrometer consists of a reflection grating that produces longitudinal dispersion, a conventional SHS that produces lateral dispersion and interference pattern, and a cylindrical lens.

The theory of CDSHS is derived from grating equations and geometric optics, which can simultaneously receive multiple independent interferograms corresponding to different spectral regions on one detector for a polychromatic source.

Appropriate parameters of the interferograms (i.e., width, height, and location) recorded by CDSHS can be calculated via the design equations, and optimized by modifying the parameters of the gratings and the cylindrical lens.

Due to the characteristics of cross dispersion, the CDSHS can achieve a higher signal-to-noise ratio (SNR) in each detailed spectrum than that of the conventional SHS while eliminating the need for the filters or moving parts. At the same time, the strong light exceeding the detector threshold in a certain spectral region of CDSHS will not interfere with the reception and inversion of corresponding interferograms in other spectral regions. CDSHS also retains the advantages including small physical size, high field-of-view, high stability, and large luminous flux.

The comprehensive mathematical and simulation treatment provides an effective way to design a CDSHS for a wide range of applications.