| 摘要 |
PURPOSE:To prevent a light spot from greatly changing owing to variation in the wavelength of a semiconductor laser and to obtain the stable optical system by providing a grating on one surface of a conic prism. CONSTITUTION:The grating 15 is formed on the conic prism 8. In this case, a material whose refractive index N3 and wavelength variation rate dN3/dlambda of the refractive index are defined by an equation is used for the conic prism 8 of the optical system for the 2nd higher harmonics which guides laser light to a waveguide and uses the 2nd higher harmonics obtained from the waveguide by Cherankov radiation. The 2nd higher harmonics optical system which is thus constituted suppresses the expansion of the spot extremely small even if the fluctuation of the wavelength of the semiconductor laser for excitation exists. In the equation, N3 is the refractive index of the conic prism, N2 the refractive index of a clad part, lambda wavelength, and alpha the Cherenkov radiation angle. |
