Design Of Micro Fiber Optic Spectrometer Detection Receiving System

With the development of scientific research and production, the trend of spectrum examination is from indoor to outdoor in situ examination and on-line monitor. So the spectrometer is required to be more minimal in areas of exploration survey, bio-medicine and environmental monitoring and so on. A kind of portable micro fiber spectrometer, using blaze grating, and two spherical mirror, a small dispersing system based on crossing Czerny-Turner structure, CCD, CPLD(complex programmable logical device), PIC microcontrollers and so on, is designed based on this kind of requirement, its working wavelength is 200-910nm, element resolution 1.5nm. The design of instrument consists of two parts: the one is the design of optical system; the other is the design of electronics system (detection receiving system).In this paper, the second part of the design is discussed. According to the requirement of spectral measurement, the entire spectrum is detected by a CCD for one time, the selection of CCD is product of Toshiba Corporation, linear charge coupled device TCD1304AP, and then received light signal is converted to an electrical signal. The hardware circuit includes CCD signal acquisition circuit, CPLD and PIC microcontrollers, signal processing circuits, high-speed A/D converter sampling circuit, DMA circuit, memory circuit and digital signal transmission circuit. A new kind of driving and sampling system which is high integrated has been designed by using complex programmable logic device CPLD and MCU. In this system, many function modules can be generated by logic cells inside of the CPLD chip, such as CCD driving timing, the driving timing of high-speed A/D sampling and storage system and so on, sampling results temporarily stored in the RAM. In the end, the A/D results can be transmitted to PC by microprocessor for storage, processing and analysis, to resolve conflicts between a large number of CCD output data and PIC microcontrollers speeding in handling large amounts of data. With the helping of the environment of Quartus II, the CPLD is programmed in VHDL and compiled, synthesized, simulated and burned. We select PIC16F887 of MICROCHIP as microprocessor, the microprocessor software is written in assembly language. The system requires only a USB data cable be connected when working, and can use it immediately after the connection cable is connected to the computer. Finally, the testing of prototype was carried out, the test, analysis and calibration of this system have done with the Hg light and laser as standard lamp-house, and the experimental results are encouragement, while achieving the 200-910nm wavelength range measurement simultaneously.