| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect the wavelength of an external resonance laser with high precision. <P>SOLUTION: Laser light emitted from an external resonance semiconductor laser 19 impinges on a grating 20 and separated through reflection diffraction into 0th order light L0 and first order light L1. Angle of diffraction θ of the first order light L1 depends on the wavelength of laser light impinging on the grating 20. When the wavelength of laser light varies, the first order light L1 moves in the direction of an arrow 22 to vary the position of the first order light spot on a split detector 21. The wavelength can be determined by detecting the position of the spot. The first order light L1 impinges on the detector 21 through an anamorphic prism 23. A laser beam having a reduced diameter can be obtained by reducing an elliptical beam from the semiconductor laser in the long axis direction by means of the anamorphic prism 23. Consequently, detection accuracy can be prevented from degrading and noise can be prevented from increasing due to large spot size. <P>COPYRIGHT: (C)2007,JPO&INPIT |
