| 摘要 |
PURPOSE:To prevent the property of geometrical optics from varying with the wavelength of luminous flux by sticking two kinds of prisms made of materials which differ in the wavelength dispersion of a refractive index together and satisfying a specific conditional equation. CONSTITUTION:The 1st prism 2A made of the 1st material with a refractive index n1 and the 2nd prism 2B made of the 2nd material with a refractive index n2 are stucked together on a surface M to form a composite prism 2; and light is incident on the composite prism 2 at an angle theta1 from an air layer and projected at an angle theta2, and then incident on the boundary surface M at an angle alpha1 and projected from the composite prism 2 at right angles to its projection surface. In this case, the equation I holds, where DELTAn1 and DELTAn2 are dispersion values of the refractive indexes. Consequently, the projection angle does not vary with the wavelength. When this prism optical system is applied to an optical information processor, even variation in the wavelength of a light source exerts no influence. |
