| 摘要 |
PURPOSE:To obtain a stabilized laser light with a marrow spectrum bandwidth, by applying a dispersion element for eliminating noise light, which is contained in a light receiving part, to wavelength control. CONSTITUTION:A light emitted from a laser light source 21 driven by the summed current of a modulation power source 22 and a bias power source 32 passes through a sample to be measured 23, without being divided, and irradiates a dispersion element 26 together with external noise lights 25. When a frequency-modulated light with a frequency nuM by the modulation power source 22 irradiates the dispersion element 26, a primary differential signal gives a dispersion curve corresponding to a wavelength determined by the value of a bias current. The difference between the primary differential signal and a reference value represents a deviation. By applying a feedback signal to the bias power source 32 so as to make the deviation zero, the wavelength of the laser light source is stabilized in a state wherein the wavelength is determined by the reference value. The dispersion element 26 whose spectrum bandwidth is narrow can be used, thereby an external scattered light can be easily eliminated. |
