Aspheric far-infrared lenses based on hot-moldable chalcogenide glass

摘要

The far infrared lenses are widely used in vehicle and night vision instrument. A new far infrared lens is proposed to enhance their performance of danger recognition at night. It focuses on the infrared light of wavelength from 8μm ~12μm. The lens is based on the uncooled infrared detector with 320×240 pixels. Its main structure is made of one refractive-diffractive aspheric lens and two spherical lenses. To improve the luminous flux, the f-number is set to be less than 1. The field of view (FOV) of 23° is wide enough to help monitor the dangerous signal around the car or community. In addition, in order to reduce the cost and improve the machinability of aspheric diffractive lens, the hot-moldable chalcogenide glass is chosen to be the material of lenses. As a result, the MTF (modulation transfer function) values of lens exceed 0.5 for all field angles at Nyquist frequency. It shows that the lens enjoys high imaging quality.