| The topics described in this article is from the cooperation projects betweenPhysics, Jilin University and Changchun City, Jilin Province, Great Wall ofTeaching Instrument Co., Ltd. The purpose is to develop a High performancespectral instruments with more pure monochromatic light and it’s major technicalindicators have reached the advanced level of similar foreign instruments. The goalsof this instrument is to Multiple measurements of the single optical path, dualoptical, spectral calibration, spectral calibration、to accurate display of spectra、tosupport the user to set the scanning resolution, sampling time, a number ofparameters of the sampling frequency, scan range, the threshold range、with Avariety of functions to provide data storage and image preservation.The entire apparatus is composed of Optical and mechanical systems、Embedded control systems、USB communication system and PC applications.Control of the entire instrument is as follows: a host computer application softwareunder user control via the USB communication to send positioning, scan, look forzero command to the next bit machine embedded control systems. Lower machinedrive control an operation of the stepper motor, screw-driven sinusoidal rotation ofthe arm to the linear relationship of the angular displacement with wavelengthincrements, the wavelength of the linear sweep control. The scanning processsynchronization to control the stepper motor filter switch. By receiving the signal ofthe wavelength origin origin device to determine the wavelength of the originlocation. High-voltage power supply to the photoelectric multiplier tube powersupply, the spectrum of the monochromator output signal by the photomultipliertube, amplifier, data processing by the microcontroller A/D converter. After thelight intensity data into the PC via USB communication, a custom USB driveridentification, pass a series of data processing to the application and draw thespectral curve on the screen in real time.Grating monochromator control system most choose to use the RS232serial bus to communicate with the PC serial transmission distance, low cost, the developmentof simple, do not need to use the driver, but the transfer rate is slow patchinconvenient.and not too much extra serial port on a PC, due to the gratingmonochromator directly connected to the PC, no long-distance transmission, but Ihope to improve the rate of communication in order to achieve a higher samplingfrequency requirements to this subject choose to use the USB busspeed andhardware CRC support plug and play to overcome a variety of technical bottlenecksof the traditional serial communication grating monochromator.PC software design feature-rich, easy to operate, contains a wealth of academicknowledge, both higher education and professional applications, has greatknowledge hidden.In physics teaching: to provide a platform for practice disciplines to explore thevalue of, the use of the experimental system developed in this project, they canconduct a number of integrated design of experiments. Students in the experiment isnot only intuitive perception of discipline principles, repeated learning andprocessing in order to consolidate the knowledge, stimulate creative thinking canalso save the data and images.In professional applications: to provide a variety of functions: single opticalmeasurements, the order of double optical path scan measurements (further dividedinto the measurement of the transmittance and absorbance measurements), thespectral correction (including the spectral response measurement and themeasurement of spectral radiance), spectral calibration (through the analysis ofinstrumental errors of the measurement of the standard spectrum, calibration values,spectral processing, consider the impact of the calibration values in order to get amore accurate corrected spectrum).The main subject is responsible for the precision grating monochromator controlsystem software programming, including the lower machine is based on the STM32MCU module functional programming; windows platform device driverdevelopment and debugging tools package DriverStudio driver development; upand downmachine communication provisions of the agreement; the Microsoft Visual C++framework for creating, developing and debugging the application ofthe host computer; use InstallShield2008tool for step-by-step through the wizard togenerate the required installation files.After painstaking research and development and a number of debugging, andnow has achieved all the expected features and has been put into mass productionand use. |
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