High Precision Double Grating Spectrometer Optical Design

Grating spectrometer is a kind of spectral analysis instrument which is widely used at present.Based on the principle of light dispersion,it can extract spectra in different wavelength bands.With the requirements and applications of grating spectrometers in various fields,grating spectrometers are rapidly developing.They are widely used in fields such as astronomy,national defense,agriculture,and biology,and are gradually developing in the direction of high precision,portability,and intelligence.After expatiating on the application scope and future development direction of the grating spectrometer,this paper proposes a high-precision dual-grating spectrometer that uses the middle echelle grating as the main dispersive element and the planar grating as the cross-dispersion element.In order to break the limitations of one-dimensional detection elements on the one-dimensional spectroscopic apparatus in detecting the pixels and improve the resolution of the spectroscopic apparatus and the effective utilization of the detector,it is the most effective means to select the cross-dispersion spectroscopy system.First,the cross-dispersed spectroscopy system enables spectral instruments to be used in a wider spectral band;second,the cross-dispersion spectroscopy system can split light in two mutually perpendicular directions to form a two-dimensional spectrum,which can be performed using a two-dimensional area array CCD.Detection;Again,the cross-dispersion spectroscopy system can solve the problem of spectral overlap in mid-echelon gratings,thereby increasing spectral resolution and light efficiency.The Czerny-Turner structure is selected for this spectrometer,mainly based on the compact structure of Czerny-Turner,which can effectively reduce aberrations and have better ordinary characteristics;and the angle between the outgoing light and the outgoing light is fixed in the system.There is no need to move parts,the system is more stable and reliable;using two-dimensional detectors to achieve full-spectrum direct reading,the corresponding degree is better,the instrument response speed is faster,and can achieve high intelligence and automation.According to the requirements of the system structure and design requirements of the Echrotron grating spectrometer,the paper preliminarily calculates and determines the design parameters of each component of the system,derives the system equations,and places the structure into the ZEMAX software.The system performs simulation optimization.The structure of double gratings must adopt complex coordinate transformation in three dimensions of space,which increases the difficulty of system simulation.Multiple systems were used to optimize the overall system for different wavelength ranges,and the optimal solution was finally obtained,and the system tolerance analysis was completed.The final simulation results show that the optical design scheme of the high-precision dual-grating spectrometer is feasible and reliable;the system structure is simple,the design and production costs are reduced,and the stability is good;the design index requirements can be met.