Patent ID: 6552851
Filing Date: 2003-04-22
Classification: G02B,H01S

Abstract:
An achromatic beam-shaping prism, which converts the cross section of a beam incident onto an input surface by a given factor in a specific direction, thereby providing a beam shaping function to a beam output from an output surface of the prism, said achromatic beam shaping prism comprising:a single prism in which a diffraction grating having a pitch dâ€² which satisfies the following Equation (2) is formed on an input surface of the prism dâ€²[n&lgr;2 sin {sinâˆ’1(sin &thgr;4/n&lgr;2)+&agr;}âˆ’n&lgr;1 sin{sinâˆ’1(sin &thgr;4/n&lgr;1)+&agr;}]=&lgr;1âˆ’&lgr;2â€ƒâ€ƒEquation (2) wheredâ€² is the pitch of the diffraction grating at the input surface of the prism, &lgr;1 is the reference wavelength of the incident beam, &lgr;2 is the wavelength of the incident beam after the change in wavelength of the light source from the reference wavelength, n&lgr;1 is the index of refraction of the prism at wavelength &lgr;1, n&lgr;2 is the index of refraction of the prism at wavelength &lgr;2, &thgr;4 is the angle the output beam makes with the surface normal to the output surface of the prism, and &agr; is the apex angle of the prism.