PDF Detection and Measurement of Infrared Radiation

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Glenn J. A review of the thermal biology and ecology of molluscs, and of the use of infrared thermography in molluscan research Laurent Seuront , Terence P.

Ng , Justin Adam Lathlean. Reconfigurable test execution systems machine and process development Cochet Martin. References Publications referenced by this paper. Quantum well infrared photoconductors in infrared detectors technology Antoni Rogalski. Electro-optical imaging : system performance and modeling Lucien M. Charge coupled semiconductor devices W.

Boyle , George Elwood Smith.

Detection and Measurement of Infrared Radiation

However, the signal produced by the detector array 20 in alternate frames is of opposite polarity and so it adds in the amplifier The switch operates in synchronization with the chopper 16 to apply a received signal either to the inverting input or noninverting input of an inverting amplifier Specifically, when the chopper 16 is open or passing incident infrared radiation, the switch applies the signal from the amplifier to the inverting input of the amplifier , and when the chopper is closed or interrupting the application of radiation to the detector array 20, the switch passes the received signal to the noninverting input of the amplifier The purpose of this is to provide a sequence of signals which are of the same polarity.

Thus, when a signal of positive polarity is produced by a detector element of the detector array 20, the amplifier produces a signal of negative polarity representing the difference between the positive signal produced by the detector element and the previously received negative signal produced by the element. This negative difference signal is then applied to the switch which in turn applies it to the inverting input of the amplifier since, at this time, the chopper is open.

When a negative signal is produced by a detector element of the detector array 20, the amplifier produces a positive signal representing the difference between the negative signal produced by the detector element and a previously received positive signal. This positive difference signal is applied to the switch which then applies the signal to the noninverting input of the amplifier In this manner, a train of positive pulses are produced by the amplifier The signal is then applied to a summing node where it is added to a signal stored in a memory and fed back via another attenuator The memory in this embodiment is an analog memory having a memory position or location corresponding to each of the detection elements of the detector array Each time a signal from a detector element is applied to the summing node , it is added to the signal stored in the memory in the location dedicated to that detector element.

Thus, the signals produced by each detector element are accumulated or integrated in the memory over some predetermined period of time. The purpose of the attenuator and is simply to maintain the accumulated or integrated signals within some predetermined range of magnitude. If X is equal to Z, then an accumulated or integrated signal would be equal in magnitude to an input signal to the attenuator after about 2X frames of input.

The time period over which the signal accumulation or integration would take place would be determined by the sensitivity desired by the user as previously discussed, and is a function of X as seen above. The output from the processor 36 and in particular the memory is applied to a utilization device 40 FIG. In the manner described, infrared radiation is detected using a solid state detection array and thermal diffusion in the array is minimized by providing relatively fast chopping of the incident radiation.

The reduction of sensitivity due to the fast chopping is recovered by providing electronic integration or accumulation of the signals produced by the detector elements. It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention and the appended claims are intended to cover such modifications and arrangements.

A pyroelectric infrared radiation detection system includes a high density solid state pyroelectric detector array for detecting infrared radiation impinging thereon and for producing signals representing the detected radiation, apparatus for readout of the signals from the detector array, and an optical chopper for successively interrupting the radiation impinging on the detector array.

In some applications, an integrating device for integrating the signals produced by the detector array would also be included. The optical chopper interrupts or chops the infrared radiation at a relatively high rate to reduce thermal diffusion in the detector array and thereby improve the spatial resolution. In low radiation intensity applications, signals which might otherwise be lost due to the fast chopping are recovered by providing electronic integration or accumulation of the signals produced by the detector array.

What is claimed is: 1. A pyroelectric infrared detection system comprising a pyroelectric detector array having a plurality of individual detector elements, each for detecting infrared radiation applied to the array and for producing signals representative of detected radiation,. A pyroelectric infrared detection system as in claim 1 wherein said pyroelectric detector array comprises a layer of pyroelectric material,.

A pyroelectric infrared detection system as in claim 2 wherein said pyroelectric detector array further comprises an output conductor coupled to each of said detector means, and means for causing each of said detector means to sequentially apply the signals produced thereby to said output conductor.

A pyroelectric infrared detection system as in claim 1 wherein said integrating means comprises memory means having a plurality of storage locations for storing signals applied thereto, and. A pyroelectric infrared detection system as in claim 4 wherein each detector element of said pyroelectric detector array is adapted to produce a signal of one polarity during application of radiation to the element and to produce a signal of opposite polarity during interruption of the application of radiation to the element, said pyroelectric infrared detection system further comprising amplifier means having an inverting input and a noninverting input, and an output is coupled to said adder means, and.

A pyroelectric infrared detection system as in claim 5 further comprising an attenuator coupled between the output of said amplifier means and said adder means for attenuating the signals applied by the amplifier means to the adder means. A pyroelectric infrared detection system as in claim 6 further comprising means coupled between the pyroelectric detector array and the switch means for producing a difference signal representative of the difference between each signal produced by a detector element of the array and the immediately succeeding signal produced by the element.

A pyroelectric infrared detection system as in claim 1 wherein said interrupting means is adapted to interrupt the application of radiation to the array at a rate from about 30 to Hertz, and wherein said integrating means is adapted to integrate the signals produced by each detector element over a period of from about 1 to frames of the interrupting means. A pyroelectric infrared detection system comprising a pyroelectric detector array having a plurality of individual detector elements spaced apart at a distance of from 0.

USA en. Method and circuit arrangement for the separation of the thermal background signal of an IR detector from the useful signal.

What does the Infrared show us?

Thermally insulative and electrically conductive interconnect and process for making same. Method for the electronic production of thermal image reproduction and apparatus for carrying out the method. Electrical interconnection apparatus for achieving precise alignment of hybrid components. Ultra-tall indium or alloy bump array for IR detector hybrids and micro-electronics. Digital signal processing system for removing DC bias in the output of pyroelectric and similar detectors. Device for earth sensing for satellite or similar having an array of pyroelectrical detectors.

Temperature distribution measurement apparatus and its application to a human body detecting system. Spun cast IR detector arrays with integrated readout electronics and method of making the same.


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Thermal image detector with totating shutter having an increased rotation frequency and method of operation. Square sensor device for satellite or similar, with pyroelectric detector matrix. Dyck et al. CNC en. Device and method for detection and demodulation of intensity modulated radiation field.

EPB1 en. JPB2 en.

Infared radiation absorption and radiation by a surface - AQA

A-dual band IR sensor having two monolithically integrated staring detector arrays for simultaneous, coincident image readout. Bolometer-type infrared detection element, a driving method, and the detection integrated circuit. Nondestructive readout of a latent electrostatic image formed on an insulating material. Kanade et al. Bailey et al.

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Detection and Measurement of Infrared Radiation

First measurement of efficiency and precision of CCD detectors for high energy physics. EPA2 en. An AR coating typically consists of a carefully constructed stack of thin layers with different refractive indices.

The internal reflections of these layers interfere with each other so that a wave peak and a wave trough come together and extinction occurs, leading to an overall reflectance lower than that of the bare substrate surface. Anti-reflection coatings are included on most refractive optics and are used to maximize throughput and reduce ghosting.

HCAR is an optical coating commonly applied to Silicon and Germanium designed to meet the needs of those applications with optical elements exposed to harsh environments, such as military vehicles and outdoor thermal cameras. This coating offers highly protective properties coupled with good anti-reflective performance, protecting the outer optical surfaces from high velocity airborne particles, seawater, engine fuel and oils, high humidity, improper handling, etc.. It offers great resistance to abrasion, salts, acids, alkalis, and oil. Any material is characterized by a certain temperature expansion coefficient and responds to temperature variations by either increasing or decreasing its physical dimensions.

An optical system is athermalized if its critical performance parameters such as Modulation Transfer Function, Back Focal Length, Effective Focal Length, … do not change appreciably over the operating temperature range. Athermalization techniques can be either active or passive. Lenses are commonly identified by their focal length. Focal length and field of view FOV are related by the following formula:.

FOV is the angular subtense expressed in angular degrees or radians per side if rectangular, and angular degrees or radians if circular over which the optical system will integrate all incoming radiant energy. According to the above formula, as the focal length increases, the field of view for that lens will be narrower and viceversa. For instance, long range thermal infrared surveillance applications require long focal length lenses. Sensitivity of IR cameras can be increased by choosing the appropriate lens. Uncooled cameras equipped with uncooled microbolometer detectors are typically less sensitive than cooled cameras equipped with quantum detectors.

Introduction to infrared vision | Resources | Opto Engineering

However, using such wide-aperture lenses limits the depth of field that can be obtained by the imaging system. Long range thermal infrared surveillance applications require long focal length lenses, and the cost of lenses increases rapidly with focal length for uncooled camera systems and rather slowly for cooled systems. Spatial resolution Diffraction limits the resolution possible with an objective lens. Each point of the object to be viewed is imaged as a spot pattern called the an Airy disk. Its diameter is given by the following formula. This is known as the rayleigh resolution limit:.

Contact us. Home Resources Introduction to infrared vision. Introduction to infrared vision Primer on IR theory. Electromagnetic spectrum showing infrared bands. Introduction All objects with an absolute temperature over 0 K emit infrared IR radiation.