Measurement Of Time Resolved Spectrum Based On Oscillograph

The time resolved spectrum is a spectrum which reflects the transient change of physical or chemical process. The research on technique of time resolution was started from the sixties of the twentieth century. With the appearance of 10-9 Laser pulse,10-12 Laser pulse,10-15 Laser pulse and even 10-18 Laser pulse, the time resolution precision can reach 10-18second. With the rapid development of the time resolution technique, it is widely used in many fields such as material, physics, chemistry and biology. For example, it can be used to trace the quick change process of material structure and used on research of luminescence dynamics, galvano-chemistry, fluorescent lifetime imaging of human histology and etc.The time resolved spectrum can be measured by using the professional equipment for time resolved spectrum or other methods. Such as the way by coupling of the continuous laser source and boxcar, the time-correlated single photon counting technique, the phase modulation technique, the Null-detection approach, the pump-probe technique and Streak Camera technique. Compared with the above methods, the measurement of time resolved spectrum based on oscillograph is cheap, convenient, shortcut and need not other equipment. Besides, each part of the system can be transplantable, assembled and unassembled easily.The decay curve is obtained by measuring the luminescence relaxation of samples in this system, and data from the decay curve is processed to get the time resolved spectrum. Hardware design: the sample is exposed in pulsedNd:YAG LASER to creat photosignal; the wavelength of detector is separated by monochromator and detected by PMT; the data from PMT is processed, registered by oscillograph and finally imported to the computer. After repeating the above routine in several different wavelength of detector, the obtained data is processed by computer to get the time resolved spectrum. In the hardware design, insure the cost is not increase and high veracity, we use all possible resources. We use the LabVIEW to write the control programme and Serial port Data Monitoring technique to trigger the grating motor moving and change the optical wavelength. In this way, we get decay curve in different wavelength."The While Loop conditional terminal"is used to control the number of decay curve. The routine is ended automatically after the collection is over. The start wavelength, increments of wavelength and collection number can be set in the LabVIEW routine.In the field of photodetection, most of detectors such as STM, PIN, PMT or APD convert the received photosignal to current signal. But the voltage signal is used in usual equipment. So we do a Current-to-Voltage Conversion and Voltage Amplifier. The voltage signal is offered to oscillograph.In the end ,we use this system to measure the time resolved spectrum of RE Nano Materials--Y2O3:Eu3+ .We obtain forty-one decay curves in the range of 604.4nm≤λ≤644.4nm with 1nm increments under 266nm pulsed laser excitation. By using Origin, data is processed and time resolved spectrum is obtained. Compared the time resolved spectrum obtained by oscillograph with the spectrum got from 1000M-spectrometer, the time resolved spectrum reflects the change under 266nm pulsed laser excitation in time domain.The system we design satisfy the need for measuring time resolved spectrum.In this system we use the low noise resistor to process signals. Because of the low noise resistor, the system produces some noise which can influence the measurement. This is our next important problem to solve.