Multi-purpose Spectrometer Based On Usb2.0 Interface

On the basis of deeply analysis of the construction and principle of spectrometer and principle of optics, We successfully designed a multi-functional spectrometer which combines linear CCD with the computer technology. It can not only measure spectrum curve, but also measure the thickness of optical film and the reflection of all kinds of optical element.The multi-functional spectrometer's data acquirement system is based on the interface of USB2.0. Theoretically speaking, The USB2.0 interface can realize the high data transmission speed of 480Mb/s. The Philips 1SP1581 which has DMA interface is selected, high data transmission speed with computer is realized through DMA interface. The driver circuit of CCD is realized by CPLD (Complex Programmable Logic Device). In the multi-functions spectroscope's optical system, ring-shape aperture illuminates is used to reduce the sample's undersurface's reflection, then enhance the measurement precision of the reflectivity.The firmware of ISP 1581 and the drivers of USB2.0 are realized in this thesis. Based modular design method, a new spectrometer software is made in language VC++, it mainly involves spectrum curve capturing subprogram, curve zooming subprogram, writing data record subprogram, wavelength calibrating subprogram, reflectivity measuring subprogram, the film thickness caculating subprogram , etc. The software includes user-friend interface, functionally complete menu, thus operating very easily.The spectral measurement range of the spectrometer is from 380 to 780nm, and the spectral resolution is about lnm. At the end of the thesis, a summary analysis of factors influencing measurement precision was discussed, some methods to improve measurement precision of instrument are suggested.