| 摘要 |
PROBLEM TO BE SOLVED: To provide an infrared wide-angle single lens excellent in image- formation characteristic and having nearly uniform peripheral light quantity ratio characteristic. SOLUTION: In this single lens 1; d0 is a surface distance between a diaphragm and the 1st surface of the lens, d1 is the center thickness of the lens, (n) is the refractive index of glass material in 10μm wavelength, (f) is a focal distance, (bf) is a back focus, ideal image height at a relative field angle of 0.7 in the case the maximum field angle of a half field angle 60deg is set as 1 is y07, the main light beam image height of an actual light beam is y7, the ideal image height at the maximum filed angle is y01, and the main light beam image height of the actual light beam is y1. In such a case, when the respective field angles Dist0.7 and Dist1.0 are defined by following expressions, the following conditions are satisfied. Dist0.7=(y7-y07)/y07, Dist1.0=(y1-y01)/y01, (1) 0.15<d0/f<0.3, (2) 0.45<(d0+d1/n)/f<0.65, (3) 1.3<(d0+d1/n+bf)/f<1.5, (4) -0.25<Dist0.7<-0.2, (5)-0.5<Dist1.0<-0.45, and (6) 0.7<bf/f<1. |
