Radiation sensor with photo-thermal gain

A radiation sensor including a means for photo-thermal gain for producing an image of a scene in response to incident infrared radiation from said scene, comprising:

• optics for focusing low level incident infrared radiation emitted by the scene onto a microplatform array;
• a chopper for the incident infrared radiation disposed between the optics and the microplatform array;
• each microplatform disposed on a common substrate having a film layer including pyro-optical material which is incrementally heated by absorption of the low level incident radiation
• a detector with a plurality of photosensor pixels aligned with corresponding pixels of the microplatform array;
• a light source disposed adjacent to the microplatform array to project a second source of radiation through the microplatform array onto the detector for the purpose of transferring thermal-images formed on the microplatform layer to the associated photosensor pixels;
• said pyro-optical material with an absorption coefficient for the light source which increases with temperature thereby providing an overall increase in index of modulation beyond that obtainable with the heating effect of the low level radiation alone;
• said microplatform array and the photosensors cooperating with the chopper and the light source to produce a biased signal and a reference signal;
• and
• electronics for receiving the biased signal and the reference signal and for subtracting the reference signal from the biased signal to obtain an unbiased signal representing radiance differences emitted by objects in the scene.