US 4,788,428 A · Thermodynamics infrared imaging sensor

Abstract

An infrared imaging system is presented wherein a visual image of a scene being viewed is obtained from the thermal energy radiated from said scene. The thermal energy radiated is focused onto a plurality of means for absorbing energy from the infrared radiation, specifically a two-dimensional array of gas cells with the front end being a rigid infrared transparent window, the sides being rigid, and the rear ends being flexible membranes. Infrared radiation absorbed by the cells causes changes in the thermodynamic pressure within each cell and consequent expansion of the flexible membrane on the rear end of each cylindrical cell. The deflection of these flexible membranes is monitored and measured by either a laser interferometer system or a solid state pressure sensing system. Measurement of this deflection represents the amount of infrared radiation received at each of the plurality of gas cells. The resultant intensity of the laser interference beam is monitored with a laser interferometer and a TV vidicon camera. This resultant intensity reflects the magnitude of deflection from the cells. The TV vidicon signal which monitors the resultant intensity is processed and transmitted for two-dimensional video presentation of the viewed scene.

Claims20

Dependent claims

An infrared imaging system wherein a visual image of a viewed scene is obtained from thermal energy radiated from said scene, said system comprising:

means for receiving and focusing infrared radiation from a viewed scene, said focusing of the radiation occurring at an image plane;
means located at the image plane for absorbing and thermodynamically converting the focused radiation into a measureable physical change of the absorbing means;
means connected to interact with the means for absorbing for measuring the physical change of the absorbing means, said means for measuring outputting a signal which represents the physical changes occurring over the entire image plane;
and
means for processing and visually displaying the signal output from the means for measuring, wherein said visual display is a two-dimensional representation of the image of the scene being observed;
wherein the means for measuring comprises an interferometer system which compares changes in phase between a reference beam and a signal beam of light which is reflected from said means for absorbing.

3 more elements

An infrared imaging system wherein a visual image of a viewed scene is obtained from thermal energy radiated from said scene, said system comprising:

a first means for focusing infrared radiation received from the viewed scene, said infrared radiation being focused onto an image plane;
a plurality of means for absorbing energy from the infrared radiation, said absorbing means being placed at the image plane in a predetermined geometrical configuration, wherein each means for absorbing undergoes changes in its dimension oriented perpendicular to the image plane as determined by the thermodynamic effects of the absorbed energy;
means for measuring the change in dimension of each of the plurality of means for absorbing;
means for converting measurements of the changes in dimension for each of the plurality of means for absorbing into an electrical signal wherein information on the change in dimension for every absorbing means at any point in time is accordingly embodied;
means for processing the electrical signal output from the means for converting, wherein said means for processing converts the electrical signal to a visual display format;
and
means for visually displaying the processed electrical signal output from said means for processing;
and
means for establishing a fixed reference dimension for the dimension oriented perpendicular to the image plane for each means for absorbing, such that when thermodynamic changes occur in said means for absorbing to their dimensions oriented perpendicular to the image plane, said measuring means will measure changes in dimensions relative to the fixed reference dimension;
wherein said plurality of means for absorbing comprises a plurality of gas-filled cells of cylindrical shape with front ends being flat, rigid, and transparent to infrared radiation and placed in the image plane in a manner that a two-dimensional planar array is formed by said gas-filled cells, with cell side walls being rigid and equal in length among the plurality of cells, and with rear ends being flexible with their outer surfaces capable of reflecting visible radiation, such that the flexible rear ends are caused to expand and contract by changes in pressure of the gas caused by the thermodynamic absorption of infrared radiation by the gas;
and
wherein the means for measuring comprises an interferometer system which compares changes in phase between a reference beam and a signal beam of light which is reflected from the rear ends of the gas filled cells.

9 more elements

An infrared imaging system wherein a visual image of a viewed scene is obtained from thermal energy radiated from said scene, said system comprising:

a first means for focusing infrared radiation received from the viewed scene, said infrared radiation being focused onto an image plane;
a plurality of means for absorbing energy from the infrared radiation, said absorbing means being placed at the image plane in a predetermined geometrical configuration, wherein each means for absorbing undergoes changes in its thermodynamic state variables, pressure, volume, and temperature as caused by the effects of the absorbed energy;
a solid state sensor array placed in contact with the plurality of means for absorbing energy, said sensor array detecting changes in the thermodynamic state at each of the plurality of means for absorbing energy, said sensor array converting the thermodynamic parameters into an electrical voltage proportional to the magnitude of the amount of infrared radiation absorbed by the plurality of means for absorbing;
a solid state device for converting the matrix of voltage signals into a serial electrical output signal which contains information from all of the plurality of means for absorbing energy;
means for processing the electrical signal output from the means for converting, wherein said means for processing converts the electrical signal to a visual display format;
and
means for visually displaying the processed electrical signal output from said means for processing;
and
means periodically blocking the passage of the infrared radiation from the viewed scene to said means for absorbing, such that when the incident infrared radiation is blocked all gas cells adjust to a common quiescent thermodynamic state which yields a stable and uniform condition for the thermodynamic parameters converted to voltages for all gas cells in relation among themselves, and accordingly creates a reproducible calibration signal at the output of the solid state device for converting;
means, connected to the output of the solid state device for converting and the means for storing, for subtracting the stored signal from the immediate signal being output from the solid state device, such that a difference signal results which represents infrared intensities of the immediate viewed scene referenced to the calibration signal from the means for storing;
and
means for transforming the difference signal to an analog format for visual display;
wherein the means for processing comprises;
means for storing a portion of the output electrical signal from the solid state device for converting, said portion being the electrical signal output when the means for blocking is blocking the incident infrared radiation from the viewed scene.

11 more elements

Dependencies are inferred from the claim text.

Thermodynamics infrared imaging sensor

Life of this patent

Thermodynamics infrared imaging sensor

Life of this patent

Abstract

Claims20