Radiation sensor with photo-thermal gain
First Claim
1. A radiation sensor with thermal gain comprising:
- a microplatform including a pyro-optical film positioned above and thermally isolated from a substrate;
a first source of low level radiation incident upon the microplatform and partially absorbed causing an incremental heating of said film;
a second source of high level radiation comprised of a photonic beam incident on said film and partially absorbed heating the microplatform to a quiescent temperature;
wherein the temperature coefficient of absorption of said second source increases with the temperature of said pyro-optical film;
wherein an introduction of the first incremental heating causes the absorption of the second source to increase the temperature of the pyro-optical film with a second incremental heating that is greater than the first incremental heating; and
a detector monitoring the intensity of the photonic beam exiting the sensor platform thereby providing an output signal measurement representative of the amount of low level radiation incident on the sensor and enhanced by the further incremental heating effect from the second source thereby providing photo-thermal gain in the microplatform structure.
2 Assignments
0 Petitions
Accused Products
Abstract
A thermal sensor for low level radiation with built-in photo-thermal gain utilizing a thin film of pyro-optical material to modulate the reflectivity and/or transmission of a photonic carrier beam. The photonic carrier beam is modulated by the temperature of the pyro-optical film and detected by typically a silicon detector. A slight temperature increase of the pyro-optical film due to absorption of low level radiation increases the coefficient of absorption of the photonic carrier beam which in turn causes a further increase in temperature of the pyro-optical film. The photonic carrier beam provides power to increase the temperature of the pyro-optical film beyond the heating caused by the absorption of low level radiation alone. This thermal amplification effect provides a radiation sensor with photo-thermal gain.
-
Citations
21 Claims
-
1. A radiation sensor with thermal gain comprising:
-
a microplatform including a pyro-optical film positioned above and thermally isolated from a substrate;
a first source of low level radiation incident upon the microplatform and partially absorbed causing an incremental heating of said film;
a second source of high level radiation comprised of a photonic beam incident on said film and partially absorbed heating the microplatform to a quiescent temperature;
wherein the temperature coefficient of absorption of said second source increases with the temperature of said pyro-optical film;
wherein an introduction of the first incremental heating causes the absorption of the second source to increase the temperature of the pyro-optical film with a second incremental heating that is greater than the first incremental heating; and
a detector monitoring the intensity of the photonic beam exiting the sensor platform thereby providing an output signal measurement representative of the amount of low level radiation incident on the sensor and enhanced by the further incremental heating effect from the second source thereby providing photo-thermal gain in the microplatform structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. 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. - View Dependent Claims (17, 18, 19, 20, 21)
-
Specification