Electromagnetic energy diversion device wherein pellicle oblates responsive to very strong power density

摘要

Apparatus is disclosed for protecting delicate sensor optics frm the damaging effects of unwanted powerful laser radiation. A thin-film reflective pellicle 14 is placed in the light path of a sensor telescope. Incident light 10 is focused by some combination of optical elements 12 onto the reflective surface 28 of the pellicle laser power limiter 14. The reflected light 10 is then imaged by further optics 16 onto a detector array 18. Should a signal too strong for the detector to enter the sensor aperture with the incident light 10, the focused power at the surface of the pellicle 28 will oblate the plastic and metallic film, burning a hole in the pellicle, and the high-power light 11 will be deflected from the detector array and instead will be absorbed by the beam dump 20. A power meter within the beam dump determines when the laser threat has stopped and signals the turning machanisms 15a and 15b to turn the pellicle reflector to a fresh position at which point normal sensor operations may resume. The reflective film for the pellicle laser power limiter has a plastic supporting film placed before the reflective coating. This plastic film has the advantage that a polymer absorbs at certain specific wavelengths, so that laser light at that wavelength will be strongly absorbed and will burn a hole quickly through the pellicle reflector. The present invention provides a sensor protection system with an extremely short response time and an unmatched margin of safety.