JPH02243931A - Thermographic device - Google Patents

Abstract

PURPOSE:To add a zoom function by the scanning region variable system by changing the size of a scanning region by an optical system and disposing a reference IR source always in the end part of the scanning region thereof. CONSTITUTION:The IR rays radiated from the respective points to be scanned of a subject 9 are condensed via the optical system onto a detector 1 and the positions of the respective points thereof are moved by scanning mirrors 3X, 3Y of directions X, Y. The scanning mirrors 3X, 3Y are scanned back and forth by motors 12X, 12Y driven by driving circuits 11X, 11Y. Further, intermediate image forming planes Z1, Z2 to be formed with the subject images exist in the optical system and, for example, the band-shaped reference IR source 10 extending in the direction Y is disposed near the visual field boundary on the image forming blade Z1. The ray source 10 is moved onto the intermediate imaging plane by a moving mechanism 13. The magnification rate assignment signal generated from a zoom control circuit 14 is supplied to the circuits 11X, 11Y and the mechanism 13 and the detection signal obtd. from the detector 1 is sent via a signal processing circuit 15, an A/D converter 16 and a memory 17 to an image display device 18.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a so-called thermography device that obtains a temperature distribution image of a subject, and in particular, a thermography device that corresponds to absolute temperature by providing a reference infrared source on an intermediate imaging plane of an optical system. The present invention relates to a thermography device that can obtain a temperature distribution image.

[Prior art] Japanese Patent Publication No. 61-8369 discloses that a reference infrared source is provided outside the field of view on an intermediate image forming plane of an optical system, and this reference infrared source is provided with an image spot of an infrared detector imaged on the intermediate image forming plane. A thermographic device is disclosed that uses a scanning infrared source, which has the advantage of eliminating the need for a chopper and thus simplifying the construction.

[Problems to be Solved by the Invention] By the way, when a thermography device is provided with a so-called zoom function that enlarges and reduces a temperature distribution image and displays it, the scanning range of the optical system is not changed at all, and the sweep signal used for display in the display device is There is an electrical magnification display method that enlarges and displays the image by changing the amplitude of the image, and a variable scanning area method that enlarges or reduces the image by enlarging or reducing the scanning range of an optical system. Although the former method has a simple structure, it has the drawback that the ridges forming the image become rough and the quality of the image is degraded by enlarging it. Furthermore, although the latter requires changing the structure of the optical system so that the scanning range can be varied, the image can be enlarged or reduced without deteriorating the image quality.

In the thermography apparatus of the type disclosed in Japanese Patent Publication No. 61-8369 mentioned above, a reference infrared source is fixedly placed at the end of the field of view, and in order to obtain an image corresponding to absolute temperature, the reference infrared source is Since the infrared detector image spot must scan, the optical scanning area cannot be changed, and therefore, if a zoom function is to be provided, an electrical magnification display method must be used. Ta. Therefore, it was inevitable that the image quality would deteriorate due to zooming.

The present invention has been made in view of the above-mentioned points, and it is possible to add a zoom function using a variable scanning area method even to the thermography apparatus of the type disclosed in the above-mentioned Japanese Patent Publication No. 8369/1983. It is intended to.

[Means for Solving the Problems] In order to achieve this object, the thermography apparatus of the present invention includes an optical system for scanning and condensing infrared rays emitted from a subject, and an optical system for scanning and condensing infrared rays emitted by the optical system. In the thermography apparatus, a detector for detection and a reference infrared source disposed on an intermediate image forming surface of the optical system are biased, and the infrared rays generated from the reference infrared source can be incident on the detector. a zoom means capable of varying the size of a field of view on a subject by varying the scanning amplitude of a reciprocating scanning mirror included in the system; and a reference infrared source in the vicinity of an intermediate imaging plane set by the zoom means. It is characterized by providing a means for arranging it.

C Effect: In the thermography apparatus of the present invention, the size of the scanning area is varied by the optical system, and the reference infrared source is always placed at the end of the scanning area.

Embodiments of the present invention will be described in detail below with reference to the drawings.

[Embodiment] FIG. 1 is an optical diagram showing an embodiment of the present invention, and in the figure, 1 is a detector for detecting infrared rays from a subject. In front of the detector 1 are a detector lens 2, an X-direction scanning mirror 3X, and lenses 4 and 5 forming an afocal lens system.
, Y direction scanning mirror 3Y.

An optical system consisting of a lens 7 and an objective lens 8 is arranged. Pupil of objective lens 8 and scanning mirror 3X, BY
are at conjugate positions via lenses 4.5 and 7, respectively. The infrared rays emitted from each point of the scanning target part of the subject 9 are focused onto the detector 1 through the optical system, and the positions of each point are in the X and Y direction scanning mirrors 3X, BY.
moved by Looking at the optical path in the opposite direction, the image of the detector 1 is formed as a spot on the subject 9 by the optical system, and the image position is further scanned two-dimensionally on the subject by the scanning mirrors 3X and 3Y. I can say it.

The scanning mirrors 3X, 3Y are repeatedly scanned back and forth by motors 12X, 12Y driven by drive circuits 11X, 11Y.

The above optical system has intermediate image forming planes Zl and Z2 on which the subject image is formed, and one of these intermediate image forming planes, for example, near the field boundary on Zl, as shown in FIG. A belt-shaped reference infrared source 10 extending in the direction is arranged.

The reference infrared source is an object whose surface has an infrared emissivity of approximately 1.
The temperature is determined by a temperature sensor (not shown) A11j. The reference infrared source 10 is moved on the intermediate imaging plane by a moving mechanism 13. 14 is a zoom control circuit that generates an enlargement ratio designation signal, and this enlargement ratio designation signal is supplied to the drive circuits 11X, 11Y and the moving mechanism 13.

A detection signal obtained from the detector 1 is sent to an image display device 18 via a signal processing circuit 15 including a level clamp circuit, an AD converter 16, and a memory 17.

In the above configuration, the X-direction scanning mirror 3 is oscillated at an angle slightly larger than the desired field of view, i.e. the field of view displayed on the display, so that the intermediate imaging spot D of the detector 1 is as shown in FIG. The reference infrared source 10 is crossed over this reference infrared source 10 at the beginning of the X-direction scan, as shown in FIG. Therefore, when the scanning mirror 3 repeatedly scans in the X direction, the infrared rays generated from the reference infrared source 10 at the start of scanning will be incident on the detector 1. Therefore, if the signal processing circuit 15 clamps the detection signal from the detector 1 at the level of the period during which the reference infrared rays are incident on the detector 1, and then adds a DC component corresponding to the intensity of the reference infrared rays, the detection signal corresponds to the absolute temperature, and the temperature distribution image displayed on the screen of the display device 18 corresponds to the absolute temperature. It is assumed that the magnification ratio at this time is set to 1 by the zoom control circuit.

Here, when the zoom control circuit 14 is operated to set the magnification rate to 2, the drive circuits 11X and IIY reduce the scanning angle by the motors 12X and 12Y by half based on the designation signal specifying the magnification rate 2. The scanning area of the intermediate imaging spot D of the detector 1 on the intermediate imaging plane Zl is 1/2 in both the X and Y directions, as shown by the dashed line in FIG. At the same time, the moving mechanism 13 moves the reference infrared source 10 to a position 10' indicated by a dash-dotted line so that the reference infrared source 10 is located at the end of the narrowed scanning area. Therefore, even if the scanning area becomes narrower, the intermediate imaging spot D of the detector 1 traverses over this reference infrared source 10 at the beginning of the X-direction scan.

Therefore, when the scanning mirror 3 repeatedly scans in the X direction, the infrared rays generated from the reference infrared source 10 at the start of scanning are transmitted to the detector 1.
If the detection signal obtained from the detector is sent to the display device 18 via the processing circuit 15, the obtained temperature distribution image will be enlarged at an enlargement rate inversely proportional to the narrowed scanning area. , there is no deterioration in image quality, and moreover, it corresponds to absolute temperature.

Note that the setting of the magnification rate by the zoom control circuit 14 may be made so that it can be selected in steps, or may be made continuously variable. When selecting in steps, it is necessary to move the reference infrared source by the moving mechanism 13 in steps, and when selecting continuously, the reference infrared source must always be located at the edge of the scanning area. It needs to be moved continuously.

If the selection of the magnification rate is stepwise, for example, in two stages,
As shown in FIG. 3, a viewing frame 19 with two large and small viewing holes corresponding to two stages of magnification is prepared, a reference infrared source 10 is placed at each end of each viewing hole, and a designated The viewing frame may be moved based on the magnification designation signal so that the viewing hole of the magnification is selectively placed on the optical path.

The above embodiment is just an example, and the present invention can be modified in various ways. For example, in the above embodiment, a band-shaped infrared ray source extending in the Y direction was used in order to make the reference infrared rays enter the detector each time the X-direction scan is performed, but in the case where the reference infrared rays are made to enter the detector each time the Y-direction scan is performed. As shown by the two-dot chain line in FIG. 2, there is a band-shaped infrared source 10 extending in the X direction.
′ may be movably placed within the field of view.

Further, in the above embodiments, the present invention is applied to an optical system in which there are two intermediate image forming surfaces, but it can also be applied to an optical system in which there is only one intermediate image forming surface.

The same method can be applied to an optical system in which scanning in the Y direction is performed using a single scanning mirror.

[Effects] As detailed above, according to the present invention, even a thermography device that eliminates the need for a chopper by arranging a reference infrared source on the intermediate imaging plane can add a zoom function using a variable scanning area method. can do.

[Brief explanation of drawings]

FIG. 1 is an optical diagram showing one embodiment of the present invention, and FIGS. 2 and 3 are diagrams for explaining the operation. Infrared detector 2.4. 5. 7.8: Lens 3X
, 3Y: Scanning mirror 9: Subject 10: Reference infrared source 11X, IIY: Drive circuit 12:
Motor 13: Movement mechanism 14: Zoom control circuit 15: Signal processing circuit 18: Image display device.

Claims (1)

[Claims] (1) An optical system for scanning and condensing the infrared rays emitted from the subject, a detector for detecting the infrared rays scanned and condensed by the optical system, and a reference placed on the intermediate imaging plane of the optical system. In the thermography apparatus, the infrared rays generated from the reference infrared source are configured to be incident on the detector. A thermography apparatus comprising: a zoom means whose size is variable; and means for always arranging the reference infrared source at an end of a scanning area on an intermediate imaging plane variably set by the zoom means.