JPS62218825A - Infrared image pickup device - Google Patents

Abstract

PURPOSE:To provide an infrared image pickup device with a high temperature resolving power and a high resolution, by providing a view switching optical system between a 2-D infrared detection element having light receiving sections and dead section arranged in a matrix and a focusing optical system. CONSTITUTION:Prisms 26 and 27 are deflected by + or -theta separately in directions X and Y with galvanometers 28 and 29. Depending on the combination of said angle + or -theta of the deflection, the view of incidence into a detection element is switched from the view of first field to that of fourth field. The angle switching of the prisms 26 and 27 is performed synchronizing with the operation cycle of a detection element 11. Following the reading out by the light receiving section 12 of the element, the element is at rest maintaining a fixed angle rela tionship prisms is made between the end of the storage action and the start of the storage action in the subsequent field. This provides an effect the same as that obtained by increasing the number of pixels of a 2-D detection element four times that is, equivalent to the reading by a detection element which would have the dead sections act as light receiving section in substance thereby assur ing a high resolution.

Description

[Detailed Description of the Invention] [Summary] A two-dimensional infrared detection element in which a light-receiving part and a blinding part are arranged in a matrix is used, and a field-of-view switching optical system is installed between the infrared detection element and a condensing optical system. By setting up a system (for example, a prism),
Incident infrared light from a field corresponding to the unfavorable part,
The field of view switching optical system is operated to read multiple 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-storage time of the infrared detection element.

In this way, an infrared imaging device with high temperature resolution can be obtained at a low cost.

[Industrial Field of Application] The present invention relates to the configuration of an infrared imaging device, and particularly relates to the configuration of an infrared imaging device using a novel image forming method.

An infrared imaging device detects infrared rays emitted in response to the temperature of an object and converts it into an image, making it possible to measure the temperature of the target object. Among them, devices that can two-dimensionally display the temperature distribution of a target object are, for example,
It is used for medical purposes such as diagnosing blood circulation disorders, and recently, it has also been widely used for industrial purposes such as inspecting internal defects in composite materials, thermal design of buildings and equipment, and inspecting and diagnosing cracks in concrete walls.

However, such applications require high temperature resolution.

High resolution, real-time display is required, making it necessary to use multi-element detectors. For this reason, imaging devices using six linear detection elements have been put into practical use as multi-element detectors, but the performance is still insufficient, and the practical use of multi-element secondary elements (for example, IRCOD) is difficult. It 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 and 31 is a polygon scanner.

32 is a reflecting mirror, 33 is a condensing optical system, 34 is a linear 6 detection element (a detection element made of InSb), 30J (is the horizontal scanning direction of the observation field, and 30■ is the vertical scanning direction).

As shown in the figure, in a conventional infrared imaging device, for example, a ten-sided polygon scanner 31, each of which has a different angle of inclination, is rotated using six detection elements 34 arranged at regular intervals in the vertical direction. horizontal and vertical scanning is performed in an interlaced manner, with a horizontal resolution of 60 lines and a vertical resolution of 1 line.
It forms 20 screens. Immediately, 10 fields (
The numbers 1 to 6 at the left end of the observation field of view 30 in the figure correspond to the six detection elements 34, and the IF.

2F --- is the 1st. It shows the second field,
Each field is a horizontally elongated area. Note that the arrows in the figure indicate the luminous flux.

[Problems to be solved by the invention] Now, the performance of an infrared imaging device is determined by the temperature resolution (NoiseH
Quivalent Teraperature
Difference; NET D), and its temperature resolution is determined by the number of sensing elements n.

When horizontal/vertical resolution is NX * NV v proportionality constant, there is a relationship as follows: N E T D = K7 houses ("C)".

Therefore, in order to reduce NETD and improve temperature resolution, it is clear from the above equation that a detector with a large number of detection elements n should be used.

In the conventional example shown in Fig. 5, the force is Nx
x xNy k 128X12B, NETD<0
．． 1°C is desired.

To achieve this, it is necessary to use secondary elements with a large number of elements n, but it is difficult to produce two-dimensional multi-element elements at a high yield and at low cost, and the number of pixels cannot be increased too much, resulting in problems with resolution. occurs.

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

[Means for solving the problem] The problem is that the light receiving part that reads the incident infrared light from each pixel and the insensitive part that is not sensitive to the incident infrared light are arranged in a matrix. A two-dimensional infrared detection element is provided, and a visual field 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 a field corresponding to the dead area. By operating the field-of-view switching optical system (for example, switching according to the non-accumulation time of the infrared detection element) and reading a plurality of fields with the light receiving section and displaying the field output as one pixel, This problem is solved by an infrared imaging device that forms one frame of image using multiple fields.

[Function] That is, the present invention provides a two-dimensional infrared detection element in which a light receiving part and a non-sensing part are arranged in a matrix, and a visual field switching optical system is provided between the infrared detection element and the condensing optical system. (for example, a prism), the incident infrared light from the field corresponding to the unobtrusive area is read by the light receiving unit 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-storage time of the infrared detection element.

In this way, an infrared imaging device with high temperature resolution and high resolution can be produced at a low cost.

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

FIG. 1 shows a two-dimensional sensing element 1) of an infrared imaging device according to the present invention, and this example is a case of 3×3 pixels.
Reference numeral 12 is a light receiving section, 13 is a light receiving section, and 14 is a pixel. That is, a pixel is formed by one light-receiving section and three non-transparent sections, and the numbers 1 to 9 in the figure are the numbers of the light-receiving sections. The size of this detection element 1) is, for example, several tens to 100 light receiving parts.
It has a shape of about 5 μm square and three blind parts of the same size around it.

Next, FIG. 2 (al, (bl) is a diagram explaining the principle of the configuration according to the present invention, and FIG. 2 (a) shows a captured image. It shows the direction in which the field of view is switched so that incident light from the field of view corresponding to the blind area can be received.

In this way, the field of view is switched to sequentially capture images and display the images, but in this example, the 3 x 3 pixel detection element becomes equivalent to the 6 x 6 pixel detection element, and the 6 x
6 images can be displayed, and FIG. 2(b) shows the displayed image. In addition, at this time, the dimensions of the light receiving part are 1
Optical settings are made to correspond to a pixel angle of 14°.

Next, FIG. 3 shows the configuration of an imaging device 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, and 21, 22, 23, and 24 are the first . 2nd゜3rd. The field of view of the fourth field, 25 is a condensing optical system.

26 and 27 are prisms for switching the field of view in the X direction and Y direction, respectively, 28.29 are galvanometers (or step motors) for swinging the prisms 26 and 27 in the X direction and Y direction by an angle of ±θ, respectively; 1) is It is a two-dimensional sensing element.

By combining the deflection angles ±θ of the prisms 26 and 27 for switching the field of view in the X direction and the X direction, the field of view incident on the detection element can be switched from the field of view of the first field to the field of view of the fourth field. That is, such prisms are made of germanium, sapphire, etc., and their thickness,
Using the refractive index and the deflection angle θ as a function, the photosensitive portion of the sensing element can be deflected by a certain width in the X direction or the Y direction, thereby making it possible to switch the field of view.

Now, the deflection angles in the X and Y directions are θX.

Assuming that θy is positive in the counterclockwise direction, the field of view of the first field corresponds to when θX = -θ, θy = +θ, and the field of view of the second field corresponds to θX = +θ, θy = 10θ, and the field of view of the third field. is θX=+θ, θy=-θ, and the field of view of the fourth field is θ=-θ.

They correspond to each case when θy=−θ. In the operating state diagram of Fig. 4, (al and (bl) indicate the deflection angles with respect to the field of view in the X and Y directions, and (C) indicates the field number of the field of view read when stationary after switching. There is.

Now, such angle switching of the prisms 26 and 27 is performed in synchronization with the operating cycle of the detection element 1), and while the light receiving section 12 of the element is reading (receiving light) and performing an accumulation operation, the prisms 26 and 27 are switched at a constant angle. The prism is switched while maintaining the relationship and remaining in a stationary state from the end of the accumulation operation until the start of the accumulation operation of the next field, that is, while the read operation is being performed in a register such as COD. . (d) in the operating state diagram of FIG. 4 illustrates the storage readout state of the sensing element.

Figure 4(e) shows the time required to read the field - Figure 4(e)
f) indicates the time required for one frame of display image, and thus, one frame is formed by displaying images from the first field to the fourth field read by switching the field of view.

According to the imaging device configured in this way, the same effect as quadrupling the number of pixels of the two-dimensional sensing element can be obtained, and the detection element whose insensitive area is essentially the same as the light receiving area can be used for reading. Become. Moreover, since the two-dimensional sensing element formed as shown in FIG. 1 has few light-receiving parts and many non-sensing parts, it can be formed at a high yield and at low cost. In addition, since observation is performed with four times the number of pixels, the resolution is high and detection errors are reduced.
It becomes an imaging device with high temperature resolution.

Note that since the imaging device according to the present invention performs field of view switching using focused light, a small field of view switching optical system (prism) can be used, which has the advantage that the imaging device can be made smaller.

[Effects of the Invention] As is clear from the description of the embodiments above, according to the present invention, an infrared imaging device with high temperature resolution and high resolution can be obtained at a low cost, and the configuration of the imaging device is extremely excellent. I can do it.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a detection element of an infrared imaging device according to the present invention, Fig. 2 +8) and (b) is a diagram explaining the principle of an infrared imaging device according to the present invention, and Fig. 3 is a diagram illustrating the principle of an infrared imaging device according to the present invention. FIG. 4 is a diagram showing the operating state of the infrared imaging device; FIG. 5 is a diagram showing the configuration of a conventional infrared imaging device. In the figure, 1) is a two-dimensional detection element, 12 is a light receiving part, 13 is a dead part, 14.14° is a pixel, 20 is an observation field of view, 2O3 is a field of view for one pixel of the detection element - 21, 22,
23 and 24 are the first. Second. Third. 4th field field of view, 25 is a condensing optical system;

Claims (2)

[Claims] (1) Equipped with a two-dimensional infrared detection element in which a light receiving part that reads incident infrared light from each pixel and a dead part that is not sensitive to the incident infrared light are arranged in a matrix, A field of view switching optical system is provided between the external detection element and the condensing optical system, and the field of view switching optical system is operated to direct incident infrared light from a field corresponding to a dead section of the infrared detection element. read a plurality of fields with the light receiving part of the infrared detection element,
An infrared imaging device characterized in that each pixel output of one field is displayed as one pixel, and one frame of image is formed using a plurality of fields. (2) The visual field switching optical system is composed of a prism that operates at a constant deflection angle θ in the X direction and the Y direction with respect to the optical axis of the condensing optical system, and is synchronized with the non-accumulation time of the infrared detection element. 2. The infrared imaging device according to claim 1, wherein the prism is switched to each field.