JPH0652196B2 - Infrared thermal imager - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared thermal imaging apparatus for optically scanning an infrared image of an object radiating heat to obtain an image.

[0002]

2. Description of the Related Art In recent years, an infrared thermal imager which optically scans an infrared image of an object radiating heat to obtain an image has been used for various thermal analyses.

One of the devices of this type is a mechanical raster scanning infrared thermal imaging device shown in FIG. This device is 10
Rotating mirror 2 formed in an annular shape in which the vertical angle of plane mirror 1 is slightly different, silicon window 3 that blocks visible light and transmits only infrared rays, rotating mirror 2
The return mirror 4 that totally reflects the infrared image of the object reflected on the plane mirror 1, the condenser lens 5 that forms the reflected light of the return mirror 4 on the infrared detector 6, and the output electric signal of the infrared detector 6 is amplified. An amplifier 7 is provided, and the output of the amplifier 7 is subjected to various kinds of signal processing and supplied to a display device such as a cathode ray tube to display a thermal distribution image of an object, that is, a thermal image.

In the device constructed as described above, only infrared rays from an object pass through the silicon window 3 and reach the rotating mirror 2, but the rotating mirror 2 is provided with the plane mirror 1 shifted vertically by 1 degree. Therefore, each plane mirror 1 scans laterally the part of the object which is slid once in the vertical direction. One rotation of the rotary mirror 2 scans a range of 10 degrees in the vertical direction.

On the other hand, since the infrared detector 6 receives the thermal image signal at every 1 degree by the flat mirror 1 on one surface, one rotation of the rotary mirror 21 scans the object in the vertical direction at 10 degrees. Further, in the horizontal direction, the horizontal viewing angle (15 degrees in this example) of each plane mirror 1 of the rotating mirror 2 is scanned.

[0006]

On the other hand, diagnostic or inspection methods using thermal images have been attracting attention in various fields. For example, thermal analysis such as thermal analysis of tires during high speed rotation and combustion state analysis of engines. There is a demand for observing phenomena that change at high speed.

However, since it is necessary to change the mounting angle of the rotary mirror little by little in the conventional apparatus, it is necessary to reduce the area of the plane mirror of the rotary mirror of the conventional mechanical raster scanning infrared thermal imaging apparatus. Has a limit,
In addition, since the plane mirror is inclined on each surface, there is a limit in reducing the thickness. Therefore, the conventional device cannot reduce the size and weight of the rotating mirror to rotate at high speed,
The problem is that it can only image slow-moving objects. In addition, the device itself is larger than a general optical camera or the like and is inconvenient to handle.

The present invention has been made in view of such a situation, and is to make it possible to obtain high-speed mirror rotation.

[0009]

In order to solve such a problem, a first aspect of the present invention is directed to a rotary mirror having a plurality of reflecting surfaces parallel to a rotary axis and a rotary mirror intersecting the rotary mirror at a predetermined angle. And a second cylindrical lens for converging the infrared light reflected by the rotating mirror into parallel light, and the first cylindrical lens for collecting the infrared light emitted from the object on one specific reflecting surface of the rotating mirror. With a cylindrical lens,
The reflecting surface of the rotating mirror, which is arranged on an axis parallel to the second cylindrical lens surface and inclined with respect to the lens surface by a predetermined angle, sequentially moves each time a predetermined horizontal viewing angle is scanned, and The oscillating mirror that reflects the focused light from the cylindrical lens of No. 2, the convex lens that collects the reflected infrared rays from the oscillating mirror, and the infrared detector provided at the condensing point of the convex lens. .

In a second aspect of the present invention, a rotating mirror having a plurality of reflecting surfaces parallel to the rotation axis and infrared rays emitted from the object are arranged so as to intersect the rotating mirror at a predetermined angle. A first cylindrical lens (23) for converging on a reflecting surface, and a reflecting surface of the rotating mirror arranged on an axis parallel to the first cylindrical lens surface and inclined at a predetermined angle with respect to the lens surface. Each time a predetermined horizontal viewing angle is scanned, an oscillating mirror (2) that moves in sequence and reflects infrared rays incident from an object (10) radiating heat
5), a second cylindrical lens (24) that focuses the infrared light reflected by the rotating mirror into parallel light, and a convex lens (2) that focuses the output light of the second cylindrical lens.
7) and an infrared detector (28) arranged at the condensing point of the convex lens.

[0011]

According to the first aspect of the invention, the infrared image of the object is vertically compressed by the first cylindrical lens and projected planarly on the plane mirror of the rotating mirror. The image compressed and projected on the plane mirror is diffused after being reflected by the plane mirror. Then, the diffused infrared rays are focused into parallel light by the second cylindrical lens, and the parallel light is reflected by the oscillating mirror. Therefore, the angle of incidence on the oscillating mirror differs depending on the vertical position reflected by the plane mirror. However, of the infrared rays incident on the oscillating mirror, only the infrared rays having a predetermined angle are incident on the infrared detector. Therefore, by changing the swinging position of the swinging mirror, the light reflected from any part of the plane mirror can maintain its predetermined angle and is incident on the infrared detector, so that vertical scanning is performed. Since the horizontal scanning is performed by rotating the rotating mirror, the entire image of the object can be obtained by rotating the rotating mirror and swinging the swing mirror.

In the second invention, a part of the object in the vertical direction is projected onto the oscillating mirror, and the infrared rays reflected by the object are focused into a one-dimensional image by the first cylindrical lens and projected onto the rotating mirror. The infrared light reflected and diffused by the rotating mirror is focused into parallel light by the second cylindrical lens, then focused by the focusing lens, and detected by the infrared detector. In this state, the rotary mirror rotates to perform horizontal scanning. Since the vertical direction of the entire object can be scanned by changing the swing angle of the swing mirror, the entire image of the object can be obtained by swinging the swing mirror and rotating the rotating mirror.

[0013]

EXAMPLES Examples will be described below with reference to the drawings. 1 and 2 are views showing the arrangement of an optical system of an apparatus of the present invention, FIG. 1 is a plan view thereof, and FIG. 2 is a side view of FIG.
3 and 4 are views showing the optical paths of the device shown in FIG. 1, FIG. 3 is a plan view thereof, FIG. 4 is a side view, and FIG. 5 is a perspective view.

In these figures, reference numeral 20 denotes an octahedral rotating mirror, and each surface of the octahedron (hereinafter referred to as a plane mirror) 21 having a mirror finish is arranged in parallel with the axis of the rotating shaft 22. It is arranged in a ring. Now, the infrared rays 11 emitted from the object 10 enter the plane mirror 21 through the first cylindrical lens 23, are compressed in the vertical visual field direction (the direction perpendicular to the paper surface in FIG. 1), and are reflected on the plane mirror 21 of the rotary mirror 20. An infrared image 12 is formed on the object 10, and the flat mirror 21 horizontally scans the object 10 as the rotary mirror 20 rotates.

The rotating mirror 20 rotates to reflect the infrared rays 11 from the object 10 to the second cylindrical lens 24, but in order for the reflected infrared rays to reach the second cylindrical lens 24, the first cylindrical lens 24 is used. It is necessary that the axis of 23 and the surface of the plane mirror 21 are inclined. Therefore, in the rotary mirror 20, at least in the section where the plane mirror 21 scans the object 10 in the horizontal direction, the axis of the cylindrical lens 23 and the plane of the plane mirror 21 maintain the inclined relationship.

The infrared image 12 is reflected by the plane mirror 21 and diffused in the vertical direction and is incident on the second cylindrical lens 24, where it becomes parallel light 13 and is reflected by the oscillating mirror 25 to be further reflected. Fixed mirror 2
Total reflection is performed by 6 toward the condenser lens 27. The parallel light 13 incident on the condenser lens 27 is focused and imaged on the infrared detector 28.

As described above, the infrared light reflected by the rotary mirror 20 is focused into parallel light and reflected by the oscillating mirror 25, but only the light reflected by the oscillating mirror 25 at a predetermined angle reaches the folding mirror. Therefore, by swinging the swing mirror 25, infrared rays reflected from any position in the vertical direction of the rotary mirror 20 can reach the folding mirror 26. That is, vertical scanning can be performed by the oscillating mirror.

On the other hand, since the horizontal scanning is performed by the rotation of the rotary mirror 20, the horizontal scanning of the object 10 is performed by one plane mirror of the rotary mirror 20. Now, if the swing mirror 25 is fixed and the rotary mirror 20 is rotated so that only one of the plane mirrors 21 scans the object 10 in the horizontal direction, one scanning line is obtained.

Next, after the movable mirror 25 is slightly moved, the rotary mirror 20 is rotated again by an amount equivalent to one plane mirror 21, so that scanning lines of different portions in the vertical direction of the object 10 can be obtained. When the oscillating mirror 25 is moved each time the plane mirror 21 moves to the adjacent portion in this manner, the obtained scanning lines sequentially move in the vertical direction of the object 10.

Therefore, in this apparatus, the amount of swing of the swing mirror 25 is adjusted so that one rotation of the rotary mirror 20 moves the vertical scanning position of the object 10 by 1/10. Therefore, each time the plane mirror 21 moves to the adjacent one, the oscillating mirror 25 moves vertically by ⅛.

In this way, the first one of the rotating mirrors 25 is
By rotating, the vertical direction of the object 10 is scanned 1/10, and the adjacent one in the vertical direction is scanned by the next one rotation. Therefore, when the rotating mirror 25 rotates 10 times, the entire vertical range of the object 10 is scanned. Become.

From the rotating mirror 20, one pulse of vertical synchronizing signal is generated for each rotation of the mirror, and each plane mirror 2 of the mirror 20.
Two kinds of synchronizing signals of the horizontal synchronizing signal for 1 are output, and the horizontal synchronizing signal is such that eight pulses are generated when the rotating mirror 20 makes one rotation. Then, the oscillating mirror 25 is configured such that the horizontal synchronizing pulse is supplied to a step motor (not shown) and tilts stepwise in the vertical direction as described above.

In the above description, the swing mirror 25
Although the tilting of is performed by the step motor, it is also possible to use a torque motor for bidirectional scanning.
In this case, the time required for the swing mirror 25 to return to the initial position is shortened, so that the rotary mirror 20 can rotate at high speed. Further, the swing mirror is 1/10 in the vertical direction of the object 10.
However, the entire vertical direction is represented by eight scanning lines by one rotation of the rotary mirror 20, and a different portion is scanned by the next one rotation of the rotary mirror 20. The entire object 11 may be represented by 80 scanning lines by rotating the rotating mirror 20 ten times.

The optical path of the device configured as described above is shown in FIG.
And as shown in FIG. That is, the light beam scanned up and down by the swing mirror 25 that scans in the vertical direction is condensed by the cylindrical lens 24 only in the vertical direction. The scanning surface (plane mirror) 21 of the rotating mirror 20 is placed at the position of this converging point (focal point) to perform scanning in the horizontal direction.

The light beam reflected and scanned on the surface of the rotating mirror 20 spreads again, but the cylindrical lens 2
It is returned to a parallel light flux at 3. Therefore, infrared rays can be detected by the infrared detector 28 without sacrificing the brightness of the optical system (F value).

Since each of the plane mirrors of the rotary mirror 20 need only be arranged in parallel with the rotation axis, it can be made smaller than a conventional one that has different angles in the vertical direction. Therefore, high speed rotation is possible.

In the first invention, as shown in FIG. 2, an object 10 is projected on a rotating mirror 20, and the object 10 is projected onto the swinging mirror 2.
5 is used for vertical scanning, but in the second invention, as shown in FIGS. 6 to 8, vertical scanning is performed by the swing mirror 25a, and horizontal scanning is performed by the rotary mirror 20.

FIG. 6 is a plan view, FIG. 7 is a side view, and FIG. 8 is a perspective view. As shown in FIG. 7, in this example, the object 10 reflected on the plane mirror 26a is moved vertically by the swing mirror 26a. It is scanning. In this way, the rotating mirror 20 does not show the entire image of the object 10 but a one-dimensional image and the position of the one-dimensional image does not change, so that the rotating mirror 20 may be smaller than in the first example.

[0029]

As described above, according to the present invention, each reflecting surface of the rotating mirror is arranged parallel to the rotation axis of the mirror, and the infrared rays are incident on the reflecting surface and the reflected infrared rays are collected. Since it is performed through a pair of cylindrical lenses, the vertical dimension and thickness of the rotating mirror can be reduced, and the rotating mirror can be rotated at high speed, so that it is possible to image a fast-moving object, and at the same time, the device can be used. It has an effect that it can be downsized and it can be easily handled.

[Brief description of drawings]

FIG. 1 is a plan view showing the configuration of an embodiment of the first invention.

2 is a side view of the device of FIG.

FIG. 3 is a plan view showing an optical path of the apparatus shown in FIG.

4 is a side view of the device of FIG.

5 is a perspective view of the device of FIG.

FIG. 6 is a plan view showing an embodiment of the second invention.

FIG. 7 is a side view showing an embodiment of the second invention.

FIG. 8 is a perspective view showing an embodiment of the second invention.

FIG. 9 is a schematic diagram showing an example of a conventional mechanical raster scanning device.

[Explanation of symbols]

 10 Object 11 Infrared 12 Infrared Image 13 Parallel Light 20 Rotating Mirror 21 Plane Mirror 22 Rotating Axis 23, 24 Cylindrical Lens 25, 25a Oscillating Mirror 26, 26a Fixed Mirror 27 Condensing Lens 28 Infrared Detector

Claims (2)

[Claims] 1. An infrared thermal imaging apparatus for obtaining an image by optically scanning an infrared image of an object radiating heat, wherein a rotating mirror (2) having a plurality of reflecting surfaces parallel to a rotation axis.
0), and a first cylindrical lens (23) arranged so as to intersect the rotating mirror at a predetermined angle and condensing infrared rays emitted from the object on one reflecting surface of the rotating mirror. A second cylindrical lens (24) for focusing the infrared light reflected by the rotating mirror into parallel light; and a second cylindrical lens (24) on an axis parallel to the second cylindrical lens surface and inclined at a predetermined angle with respect to the lens surface. An oscillating mirror (25) that is arranged and that sequentially moves the reflecting surface of the rotating mirror every time a predetermined horizontal viewing angle is scanned to reflect the focused light from the second cylindrical lens; Convex lens that collects reflected infrared rays (2
7) and an infrared detector (2) arranged at the condensing point of the convex lens.
8) An infrared thermal imaging device comprising: 2. An infrared thermal imager for optically obtaining an image by optically scanning an infrared image of an object radiating heat, wherein a rotating mirror (2) having a plurality of reflecting surfaces parallel to a rotation axis.
0), a first cylindrical lens (23) arranged to intersect the rotating mirror at a predetermined angle and condensing infrared rays emitted from the object on each of the reflecting surfaces, 1 is arranged on an axis parallel to the cylindrical lens surface and inclined at a predetermined angle with respect to the lens surface, and the reflecting surface of the rotating mirror is moved sequentially every time when a predetermined horizontal viewing angle is scanned, thereby radiating heat. An oscillating mirror (25a) that reflects infrared light incident from a moving object (10), a second cylindrical lens (24) that focuses the infrared light reflected by the rotating mirror into parallel light, and the second Convex lens (27) for converging the output light of the cylindrical lens, and an infrared detector (2) arranged at the condensing point of the convex lens.
8) An infrared thermal imaging device comprising: