JPH06100507B2 - Infrared imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] A two-dimensional infrared detecting element in which a light receiving portion and a dead portion are arranged in a matrix is used, and a visual field switching optical element is provided between the infrared detecting element and a condensing optical system. By providing a system (eg prism),
Incident infrared light from the field corresponding to the dead section,
The field-of-view switching optical system is operated to read a plurality of fields with the light receiving unit. In that case, the switching operation of the visual field switching optical system is performed, for example, in synchronization with the non-accumulation time of the infrared detection element.

Then, an infrared imaging device with high temperature resolution can be obtained at low cost.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a configuration of an infrared image pickup device, and more particularly to a configuration of an infrared image pickup device based on a novel image forming method.

The infrared imaging device detects infrared rays radiated corresponding to the temperature of the object and forms an image of the infrared rays, and makes it possible to measure the temperature of the target object. Among them, in particular, a device capable of two-dimensionally displaying the temperature distribution of the target object is, for example,
It has been widely used for medical purposes such as diagnosis of blood circulation disorders, and recently for industrial purposes such as internal defect inspection of composite materials, thermal design of buildings and equipment, inspection and diagnosis of cracks in concrete walls.

However, such applications require high temperature resolution, high resolution, and real-time display, and it is necessary to use a multi-element detector. Therefore, an imaging device using a linear 6-sensing element has been put to practical use as a multi-element detector, but the performance is still insufficient, and a multi-element two-dimensional element (for example, IRCCD) cannot be put to practical use. Is requested.

[Prior Art] An example of the configuration of a conventional infrared imaging device is shown in FIG. 5, where 30 is an observation field of view, 31 is a polygon scanner, 32 is a reflecting mirror, and 3 is a mirror.
3 is a condensing optical system, 34 is a linear 6 detector (a detector made of InSb), 30H is the horizontal scanning direction of the observation field of view, and 30V is the vertical scanning direction.

As shown in the figure, in the conventional infrared imaging device, for example, by using six detection elements 34 arranged at regular intervals in the vertical direction,
10-sided polygon scanner with different tilt angles
While rotating 31, the horizontal and vertical scanning are performed in an interlaced manner to form a screen with horizontal resolution of 60 lines and vertical resolution of 120 lines. That is, in a method of forming one frame with 10 fields (10F), numbers 1 to 6 at the left end of the observation field of view 30 in the figure are numbers corresponding to the detection 6 element 34, 1F, 2F ...
The first, second, ... Fields are shown, and each field is a laterally elongated region. The arrows in the figure indicate the luminous flux.

[Problems to be Solved by the Invention] Now, the performance of the infrared imaging device depends on the temperature resolution (Noise Equiva).
lent Temperature Difference (NETD), and its temperature resolution is n detection elements, horizontal / vertical resolution Nx, Ny, and proportional constant K, There is a relationship.

Therefore, to reduce NETD and improve temperature resolution,
From the above equation, it is clear that a detector having a large number of detection elements n may be used.

In the conventional example shown in FIG. 5, Nx × Ny = 60 × 120, n = 6 and NETD 0.2 ° C, but the target performance is Nx × N
It is desired that NETD <0.1 ° C with y128 x 128.

For that purpose, it is necessary to use a two-dimensional element having a large number n of elements, but it is difficult to produce a two-dimensional multi-element with a high yield and at a low cost, and it is not possible to increase the number of pixels so much, which causes a problem in resolution. Occurs.

The present invention proposes an infrared imaging device that can solve such drawbacks and obtain high temperature resolution.

[Means for Solving Problems] The problem is that a light receiving portion that reads incident infrared light from each pixel and a dead portion that is not sensitive to the incident infrared light are arranged in a matrix. A two-dimensional infrared detection element is provided, and a field-of-view switching optical system (for example, a prism) is provided between the infrared detection element and the condensing optical system to detect incident infrared light from the field corresponding to the insensitive section. By operating the field-of-view switching optical system (for example, switching operation corresponding to the non-accumulation time of the infrared detection element) to read a plurality of fields by the light receiving unit and displaying the field output as one pixel, This is solved by an infrared imaging device that forms one frame image in a plurality of fields.

[Operation] That is, according to the present invention, a two-dimensional infrared detecting element in which a light receiving portion and a dead portion are arranged in a matrix is provided, and a visual field switching optical system is provided between the infrared detecting element and the condensing optical system. (For example, a prism) is arranged, and the incident infrared light from the field corresponding to the insensitive section is read by the light receiving section by operating the visual field switching optical system. At this time, the switching of the visual field switching optical system is performed, for example, in synchronization with the non-accumulation time of the infrared detection element.

Then, an infrared imaging device having high temperature resolution and high resolution can be manufactured at low cost.

[Embodiment] Hereinafter, an embodiment will be described in detail with reference to the drawings.

FIG. 1 is a two-dimensional detection element of an infrared imaging device according to the present invention.
11 is shown, and this example is a case of 3 × 3 pixels.
Is a light receiving part, 13 is a dead part, and 14 is a pixel. That is, one light receiving portion and three dead portions form a pixel, and the numbers 1 to 9 in the figure are the light receiving portion numbers. The size of the detection element 11 is, for example, a shape in which the light receiving portion is about several tens to 100 μm square, and three dead portions having the same size exist around the light receiving portion.

Next, FIGS. 2 (a) and 2 (b) are diagrams for explaining the principle of the configuration according to the present invention. FIG. 2 (a) shows a picked-up image, and the arrow in the figure indicates the light reception of that number. It shows the direction in which the field of view is switched so that the part can receive the incident light from the field of view corresponding to the insensitive part. In this way, the field of view is switched and images are sequentially picked up to display an image. In the present embodiment, a 3 × 3 pixel sensing element is equivalent to a 6 × 6 pixel sensing element, ie, 6 × 6. 2B can be displayed, and FIG. 2B shows the displayed image.
At this time, the optical setting is made so that the size of the light receiving portion corresponds to one pixel 14 '.

Next, FIG. 3 shows the configuration of the image pickup apparatus according to the present invention. In the figure, 20 is the observation field of view, 20S is the field of view for one pixel of the sensing element, 21, 22, 23, and 24 are the fields of view of the first, second, third, and fourth fields that the sensing element expects in response to field switching. Reference numerals 25 and 25 are condensing optical systems, 26 and 27 are prisms for switching visual fields in the X and Y directions respectively, and 28 and 29 are prisms 26 and 27 in the X and Y directions respectively at an angle of ± θ.
A galvanometer (or a Tesp motor) 11 for swinging in the direction is a two-dimensional detection element.

By the combination of the deflection angles ± θ of the visual field switching prisms 26 and 27 in the X and Y directions, the visual field incident on the detection element is first
It is possible to switch from the field of view to the field of view of the fourth field. That is, such a prism is made of germanium or sapphire, and the photosensitive portion of the sensing element can be swung in a certain width in the X direction or the Y direction by using the thickness, the refractive index, and the deflection angle θ as a function. Therefore, the field of view can be switched.

Now, let the deflection angles in the X and Y directions be θx and θy, respectively.
If the counterclockwise direction is positive, the field of view of the first field is θx
= −θ, θy = + θ, the field of view of the second field is θx = + θ, θy = + θ, the field of view of the third field is θx = + θ, θy = −θ, and the field of view of the fourth field is θx.
This corresponds to the case of = −θ and θy = −θ. (A) and (b) in the operation state diagram of FIG. 4 show the deflection angles with respect to the visual field in the X and Y directions, and (c) shows the field number of the visual field to be read at rest after switching. Shows.

Now, such angle switching of the prisms 26 and 27 is performed in synchronization with the operation cycle of the detection element 11, and the light receiving section 12 of the element is
While it is reading (light-receiving) and performing the storage operation, it is in a static state with a constant angular relationship, and from the end of the storage operation to the start of the storage operation of the next field, that is, the CCD The prisms are switched while the reading operation is performed by the register such as. (D) in the operation state diagram of FIG. 4 illustrates the accumulation reading state of the sensing element.

FIG. 4 (e) shows the time required for reading the field, and FIG. 4 (f) shows the time required for one frame of the display image. Thus, the display image is read by switching the field of view.
An image from the field to the fourth field forms one frame.

According to the imaging device configured as described above, the same effect as when the number of pixels of the two-dimensional detection element is quadrupled can be obtained, and the insensitive section is read by the detection element substantially equivalent to the light receiving section. Become. Moreover, since the two-dimensional detection element formed as shown in FIG. 1 has a small number of light receiving portions and a large number of insensitive portions, it can be formed with high yield and is inexpensive. And since it is observed with 4 times the number of pixels, the resolution becomes high and the number of detection errors decreases.
The imaging device has a high temperature resolution.

Since the image pickup apparatus according to the present invention switches the field of view with the focused light, there is an advantage that a small field-of-view switching optical system (prism) can be used and the image pickup apparatus can be downsized.

[Effects of the Invention] As is clear from the above description of the embodiments, according to the present invention, it is possible to obtain an infrared image pickup device with high temperature resolution and high resolution at a low cost, and it is said that the image pickup device is a laterally superior device. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing a sensing element of an infrared imaging device according to the present invention, FIGS. 2 (a) and 2 (b) are diagrams explaining the principle of the infrared imaging device according to the present invention, and FIG. FIG. 4 is a diagram showing a configuration of an infrared imaging device according to the invention, FIG. 4 is a diagram showing an operating state thereof, and FIG. 5 is a diagram showing a configuration of a conventional infrared imaging device. In the figure, 11 is a two-dimensional detection element, 12 is a light receiving section, 13 is a dead section, 14 and 14 'are pixels, 20 is an observation field of view, 20S is a field of view of one pixel of the detection element, 21,22,23,24 are Fields of view of the first, second, third and fourth fields respectively, 25 is a condensing optical system, 26 and 27 are field switching prisms in the X and Y directions, and 28 and 29 are shaking in the X and Y directions. It shows a galvanometer.

Claims (2)

[Claims] 1. A two-dimensional infrared detection element comprising a light receiving section for reading incident infrared light from each pixel and a dead section having no sensitivity to the incident infrared light arranged in a matrix. A field-of-view switching optical system is provided between the infrared detection element and the condensing optical system, and incident infrared light from a field corresponding to a dead part of the infrared detection element is switched to the field-of-view switching optical system. A plurality of fields are read by the light receiving portion of the infrared detecting element by operation, and one frame image is formed in the plurality of fields while displaying each pixel output of one field as one pixel. Infrared imaging device. 2. The field-of-view switching optical system comprises a prism operating at a constant deflection angle θ in the X and Y directions with respect to the optical axis of the condensing optical system, and the non-accumulation time of the infrared detecting element. The infrared imaging apparatus according to claim 1, wherein the prism is switched to each field in synchronism with the above.