| 摘要 |
PURPOSE:To obtain a picture of even quality regardless of the level of the background temperature of a subject to be picked up, by providing a short wavelength pass filter which cuts the wavelength shorter than the cut-off length of a long wavelength of all infrared detectors on the photodetecting surface of a solid- state image pickup element. CONSTITUTION:A short pass filter 5 which absorbs the components having lengths longer than the cut-off wavelength among incident infrared rays 4 is attached close to the photodetecting surface of an IRCCD consisting of an infrared detector 2 and a charge storage/transfer part 3 which are provided on a cooled substrate 1 positioned on the focal plane of a light receiving optical system 6. The cut-off wavelength of the filter 5 is set shorter than the cut-off wavelength lambdap of all infrared detectors 2 on the IRCCD. Furthermore the temperature of the filter 5 is approximately equal to that of the cooled substrate 1 owing to the close adhesion of the filter 5. As a result, the infrared rays radiated from the filter 5 itself can be reduced satisfactorily. |
