Design And Improvement Of The System For Measuring Time-Resolved Spectrum

A new system for measuring time-resolved spectrum (TRS) is designed and improved. Pulsed excitation light is from a high-power LED driven by a signal generator (WF1946B,NF Corp.). The emission spectra of the sample are detected by a monochromator. By photoelectric transforming, a light signal of certain wavelength is converted to an electrical signal by PMT. The digital oscilloscope (TDS1012) can accomplish the function of A/D conversion and record the waveform. When the waveform data are transmitted to PC, the PC can send command to microprocessor for controlling the stepping-motor in order to adjust the detected wavelength by rotating the grating, and then the measurement is started at a new wavelength. By continuously adjusting the detected wavelength of the monochromator and recording the light signal with different wavelength, a serial of the waveform data is obtained. At last the computer can deal with the data to draw the TRS graph.This method for measuring time-resolved spectrum (TRS) is featured by parallel measuring in time scale while serial measuring in wavelength scale. It has the advantages of equipment simplicity, measurement with speediness and precision.In this article, both the hardware and the software of this system are designed and improved, including designing the circuit module with a microprocessor (AT89S52) which drives the stepping motor; making use of the RS232 serial interface to communicate between the oscilloscope and PC, as well as the microprocessor and PC; programming with VC++6.0 MFC to design the user interface for controlling; using the OpenGL toolkit to accomplish three dimensional real time drawing of the TRS etc.The sample of SrAl₁₂O₁₉: 5%Pr³⁺ was measured by this system, and its fluorescence lifetime was calculated to be 24.03±0.54μs on wavelength 622nm. In conclusion, this system can be applied to the measurement of TRS from the range between ms toμs.