To dissolve the problems distortion due to aberration given to an image by an optical system, color aberration due to such a distortion and a high order correction in the horizontal direction remaining in a spectrum, by making a field lens corrected with the color aberration a cata-dioptric lens constituted of compound lenses.
In the image system provided with both characteristics of reflection and refraction, its cata-dioptric lens group 17 is constituted of a first optical element and a second optical element. The first optical element is constituted of a dish like lens 39 made of melted quartz, and its rear side concave surface is applied with application material 41 for giving a reflection characteristics. The second optical element is constituted of the first lens 43 made of quartz, and its rear side concave surface is applied with the application material 45 for giving the reflection characteristics. Then, the curved surfaces and these positions of the first, second lenses 39, 43 are set so that primary color aberration correction in the major axial and horizontal axial directions are attained in the relation with a focus lens group 11.
WO/2002/023170 | MEASUREMENT OF PAPER OR BOARD |
JP2018080925 | COMPONENT CONCENTRATION DETECTOR |
JPH07248293 | SURFACE MODIFICATION DETECTOR SYSTEM |
CHUANG YUNG-HO
TSAI BIN-MING B