The Development Of Minimized Optic Fiber Grating Spectrometer And The Applications In Physics Experiment

Spectrum examination is widely used in scientific research and production. 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. The thesis describes a set of micro fiber grating spectrometer, which is made up of fiber, mini grating monochromator, CCD and CPLD. The CCD is the photosensitive component and has the feature of minimal size, light weight, low power consumption, linearity, low noise, wide dynamic response, real time transport and self-scans. The CCD transforms the photo intensity to electric signal. After this step, the electric signal is transformed to digital values by the electric system. At the end, these digital values are uploaded to PC where they are stored, processed and analyzed. With the help of electric system, the electric signal which is transformed from weak photo signal is amplified and the S/N ratio is increased that improves the performance of grating spectrometer. The whole electric system is under the control of the CPLD, which includes the CCD driver timing, A/D sample and transform timing, data buffer read and write timing and the communication between system and PC. The CPLD is programmed in Verilog and compiled, synthesized, simulated and burned helping the environment of Quartus II. The CPLD also supports on-line programming by JTAG, this helps the hardware of system to upgrade and update conveniently. The communication between system and PC is following the USB2.0 protocol, which support P&P (plug and play) and the data transport speed can reach to 480Mbps. The USB2.0 works with the logic process ability and response speed of CPLD matches the CCD to sample and transform photo signal quickly and real-time process. Besides these, the whole electric system is powered by the USB interface. The application program on PC is based on LabView, which has the feature of simple structure and friendly interface. The test of the Demo System shows it has the feature of wide spectrum range, high resolving power. So the system is especially suitable in the education of spectrum experimentations and the application of portable filed examination. It has been applied in the experiment teaching in university.