Design and implementation of high sensitivity micro spectrometer based on area array CCD

Overview: Spectrometer is animportant instrument for spectral detection. It is used to measure thecomposition and structure of a substance. It has the advantages of fastmeasuring speed, high accuracy and nondestructive measurement. Traditionalspectroscopic instruments, with their huge volume and high price, almost limitsuch instruments to the laboratory. In recent years, on the one hand, theurgent needs of biomedicine, science and technology agriculture and otherapplications require analytical instruments to develop in the direction ofminiaturization and intelligence. On the other hand, it is possible to make thespectrometer miniature, thanks to the development of microelectromechanical systems(MEMS) and the mass production of optical fiber devices, as well as theappearance of micro optoelectronic detection devices.

Comparedto the linear array CCD, the area array CCD is more sensitive to the spectralresponse, which is very suitable for the applications of high quantumefficiency, such as pesticide residue detection, DNA detection, fluorescencedetection and Raman spectrum detection. Therefore, the development of highlysensitive micro fiber spectrometer can broaden the applications ofspectrometers, which is of great practical significance. At present, the technologyof micro spectrometer is mostly used at home and abroad. The first method is touse MEMS technology, two element optics and integrated optics. The secondmethod is to use the miniaturization of components and systems, which is themainstream method at present. The American Brimrose company and Jet Propulsionlaboratory developed a micro crystal NIR spectrometer based on acousto-optictunable filter (AOTF) with a new type of filter technology, with a resolutionof 0.0125 nm. Relevant research institutes in China include research institutessuch as Zhejiang University, Chongqing University and Changchun Institute ofOptical Precision Machinery and Physics, CAS.

Theoptical resolution of 1 nm is obtained by using an optimized cross-asymmetricCzerny-Turner optical system structure. By combining the design methods ofDC-DC and LDO, the complex power system with 6 voltage outputs is realized throughUSB power supply. The CCD drive timing design is achieved by Verilog HDLlanguage and the signals are output through Altera's EPM7064 chip. After theCCD output video signal is converted by high-speed 16 bit AD chip AD9826, digitalsignals are stored in a separate static RAM, allowing data acquisition andreading to be separated. The sensitivity of the designed micro-high sensitivityspectrometer is 11 times of that of spectrometer based on linear array CCD. Furthermore,it has a dynamic range of 20000: 1 and a signal-to-noise ratio of 500: 1. Thiswork greatly improves the microfiber spectrometer performance.