Patent ID: 9411137
Filing Date: 2016-08-09
CPC Classification: G02B

Claim Text:
1. An infrared imaging optical system for focusing infrared radiation on an infrared detector, the imaging optical system comprising: a front lens group having a negative optical power, wherein the front lens group is configured to receive infrared radiation and comprises a first front negative meniscus lens with at least one aspherical surface and a second front negative meniscus lens with at least one aspherical surface; an intermediate lens group that is configured to receive the infrared radiation from the front lens group, wherein the intermediate lens group comprises a first intermediate lens with at least one aspherical surface, a second intermediate lens with at least one aspherical surface, and a third intermediate lens with at least one aspherical surface; a rear lens group having positive optical power, wherein the rear lens group is configured to receive the infrared radiation from the intermediate lens group, and wherein the rear lens group comprises a first rear lens with at least one aspherical surface, a second rear lens with at least one aspherical surface, and a third rear lens; and the infrared detector, wherein the infrared detector is configured to detect at least the infrared radiation with wavelengths in a range from about 3.4 microns to about 4.8 microns or wavelengths in a long-wavelength infrared spectral band; and wherein the imaging optical system has an aperture stop between the rear lens group and a focal plane located at said infrared detector; wherein, when the imaging optical system receives the infrared radiation, the imaging optical system produces only a single image, the single image being located at the infrared detector; and wherein the imaging optical system has a physical length and an effective focal length and wherein a ratio of the physical length to the effective focal length is less than about 3.0.