2012 BFY Abstract Detail Page
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||A new method to investigate the side-axis spectrum of He-Ne laser
||The experiment of side-axis spectrum of He-Ne laser is to investigate the change of the population distribution of the corresponding energy levels with or without laser output by measuring the intensity of spontaneous spectrum. The side-axis spectrum can not only show which lines are created by the stimulated radiation, but also reveal the phenomenon of population inversion in the complex of He-Ne plasma emission spectrum.
Side-axis spectrum is generally detected by movable mirror grating spectrometer with a photo-multiplier tube as the detector. This kind of spectrometer scans wavelength through grating rotation and record the intensity of each wavelength at a time. The entire spectral measurements usually take a few minutes or even longer. In order to reduce the intensity fluctuation, a beam chopper and a lock-in amplifier are necessary to get a reliable result. It increases both the cost and the complexity of the equipment.
We adopted a micro grating spectrometer for the record of the side-axis spectrum from a He-Ne laser tube. With a CCD as a detector, the entire spectrum can be recorded within tenth of a second. Thus, the lock-in amplifier is no more necessary for the setup. During the laboratory, the students can spend more time on studying laser physics instead of the operation of a lock-in amplifier.
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Fudan University, China
Physics Department, Fudan University
220 Handan Road
Anxun He, Physics Department, Fudan University, 220 Handan Road, 200433, Shanghai, China
Yifan Chen, Physics Department, Fudan University, 220 Handan Road, 200433, Shanghai, China
Cuiqin Bai, Physics Department, Fudan University, 220 Handan Road, 200433, Shanghai, China
Yongkang Le, Physics Department, Fudan University, 220 Handan Road, 200433, Shanghai, China