| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a wide-band wavelength plate having excellent reliability and to provide an optical device provided with the wavelength plate. <P>SOLUTION: The wavelength plate (1/2 wavelength plate) 25 is structured by laminating 2 birefringent plates 25A, 25B each comprising KTP (KTiOPO<SB>4</SB>) crystal to cross each in-plane optical axes D1, D2 each other at a right angle. The KTP crystal is biaxial birefringent crystal transparent in a range from visible region to near-infred region. When the KTP crystal is used as a birefringent material, the change of the birefringence in the visible light region of 400-700 nm is about 0.005 at the maximum which is 1/2 of that of quartz. Then, the degree of the phase shift in 400-700 nm wavelength is minimized to attain stable transmission characteristics over the wide-band. Because the KTP has smaller wavelength dependency compared to that of the quartz, laminated plates are reduced. As a result, a wide-band zero-order wave plate having high reliability is obtained at a low cost. <P>COPYRIGHT: (C)2008,JPO&INPIT |
