JPH0983869A - Method and device for infrared ray image pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce deterioration in the image quality by selecting a ratio of light quantity incident onto an infrared ray sensor from a measured object through a scanning optical system to a light quantity of an image of the infrared ray sensor itself incident onto again the infrared ray sensor through the reflection of the scanning optical system to be higher so as to suppress narcissus to be low. SOLUTION: An optical filter 2 whose transmissivity is ε is inserted obliquely onto an optical path for a scanning optical system 1 and an infrared ray sensor 3 to reduce the narcissus amount by the transmissivity of the optical filter. Furthermore, a face with a low reflectance is arranged to a reflection optical path of the optical filter so that the image of the infrared ray sensor reflected in the optical filter is not again made incident onto the infrared ray sensor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared imaging apparatus, and more particularly to an infrared imaging method and apparatus for reducing narcissus caused by reflection by a scanning optical system when a cooled infrared sensor is used.

[0002]

2. Description of the Related Art Conventionally, in order to reduce narcissus caused by reflection of an image of an infrared sensor by a scanning optical system,
It is necessary to sufficiently design the shape and arrangement of each optical element of the scanning optical system, and further design the antireflection film deposited on the surface of the optical element, but there are design restrictions to satisfy other optical performances. It was

Further, the amount of narcissus produced in an optical system which has been designed once and has been manufactured cannot be reduced unless the optical system is redesigned and remanufactured.

[0004]

The amount of narcissus generated by the reflection from the scanning optical system of the infrared sensor is complicated in design calculation, and the design condition must be designed while matching with other optical performances. Because I have to
This makes the design of the scanning optical system difficult.

Further, the amount of narcissus produced by a scanning optical system which has been designed once and is manufactured is easy because the factors that determine the amount of narcissus are entangled with various design parameters (shape arrangement, coating, etc.) of the scanning optical system. Has the drawback that it cannot be reduced.

An object of the present invention is to calculate the ratio between the amount of light that is incident on the infrared sensor from the object to be measured through the scanning optical system and the amount of light that the image of the infrared sensor itself is incident on the infrared sensor again due to the reflection of the scanning optical system. An object of the present invention is to provide an infrared imaging method and an apparatus thereof that realize a reduction in the amount of narcissus by increasing the size.

[0007]

The infrared imaging method of the present invention is an infrared imaging method in which infrared radiation from an object to be measured is detected by an infrared sensor cooled through a scanning optical system. And a step of partially reflecting the image of the infrared sensor reflected by the scanning optical system and transmitting the rest of the image, arranging an optical filter having an arbitrary transmittance obliquely in the optical paths of the scanning optical system and the infrared sensor, In order to prevent the image reflected by the optical filter from returning to the infrared sensor, a step of arranging a surface having a low reflectance in the reflection optical path, the image of the infrared sensor is reflected by the scanning optical system, and the infrared sensor is again provided. It is characterized in that the narcissus generated upon incidence on the optical filter is reduced in proportion to the transmittance of the optical filter.

Further, the infrared imaging device of the present invention is an infrared imaging device for detecting infrared radiation from an object to be measured by an infrared sensor cooled through a scanning optical system, and an image of the sensor itself coming from the infrared sensor and the scanning optical system. In the optical filter, which partially reflects the image of the infrared sensor that is reflected by, and transmits the rest of the image, an optical filter having an arbitrary transmittance obliquely arranged in the optical path of the scanning optical system and the infrared sensor, and the optical filter. In order to prevent the reflected image from returning to the infrared sensor, it has a surface with a low reflectance arranged in the reflection optical path, the image of the infrared sensor is reflected by the scanning optical system, and is incident on the infrared sensor again. The narcissus that occurs is reduced in proportion to the transmittance of the optical filter.

In the infrared imaging device of the present invention, an optical filter having a transmittance ε [%] obliquely inserted between the optical paths of the scanning optical system and the cooled infrared sensor, and the reflected light from the optical filter are not returned to the infrared sensor. Has a low-reflectance surface located at.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The image of the infrared sensor, which is the basis of Narcissus, passes through the optical filter, is reflected by the scanning optical system, and only the light that has passed through the optical filter again enters the infrared sensor. On the other hand, the light from the object to be measured, which is the object of measurement, passes through the optical filter once and enters the infrared sensor. Therefore, since the light from the infrared sensor passes through the optical filter twice, the amount of narcissus can be reduced by the transmittance of the optical filter as compared with the light from the object to be measured.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an infrared imaging device according to an embodiment of the present invention. In FIG. 1, the infrared imaging device includes a scanning optical system 1 that collects infrared light, an optical filter 2 having transmission / reflection characteristics arbitrarily selected, an infrared sensor 3, and a surface 4 having a low reflectance.

Next, the operation of the embodiment of the present invention will be described with reference to FIG.
This will be described in detail with reference to FIG.

FIG. 2 shows a conceptual diagram of the calculation of the amount of narcissus obtained by the present invention. In FIG. 2A, the light from the object to be measured is collected by the scanning optical system 1, passes through the optical filter 2 having the transmittance ε, and is incident on the infrared sensor 3. The signal detected by the infrared sensor 3 at this time is the intensity of the condensed light is V
When set to 1, it becomes εV1.

In FIG. 2B, the image of the infrared sensor 3 itself: V2 passes through the optical filter 2 and becomes εV2. Further, in FIG. 2C, the light is reflected by the scanning optical system 1 and again passes through the optical filter 2, so that the intensity of the light becomes .epsilon..epsilon.V2 and enters the infrared sensor 3. At this time, the amount of narcissus: NAL (A) becomes NAL (A) = ε · εV2 / εV1 = εV2 / V1.

Therefore, the amount of narcissus obtained by the present invention:
NAL (A) and conventional type Narcissus amount: NAL
Comparing (B), the transmittance of the optical filter 3 is reduced by the amount of ε.

Further, in the image of the infrared sensor 3 reflected by the optical filter 2, since the surfaces 4 having a low reflectance are arranged on both side surfaces of the optical filter 2 so as not to return to the infrared sensor 3, the amount of narcissus is increased. Does not affect.

[0018]

Since the narcissus can be easily reduced by placing the optical filter at an arbitrary position, it becomes easy to design the scanning optical system in consideration of the reduction of the narcissus.

Further, regarding the existing infrared image pickup device, the narcissus can be reduced only by disposing the optical filter and the surface having a low reflectance in the optical path without changing the design or remanufacturing of the scanning optical system. There is an effect that it can improve.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of an infrared imaging device of the present invention.

FIG. 2 is a conceptual diagram of calculation of a narcissus amount obtained by the infrared imaging device of the present invention.

FIG. 3 is a functional block diagram of a conventional infrared imaging device.

FIG. 4 is a conceptual diagram of calculation of a narcissus amount obtained by a conventional infrared imaging device.

[Explanation of symbols]

 1 Scanning optical system 2 Optical filter 3 Infrared sensor 4 Surface with low reflectance V1 Intensity of light condensed by scanning optical system V2 Intensity of image of infrared sensor itself ε Transmittance of optical filter

Claims (2)

[Claims] 1. An infrared imaging method for detecting infrared radiation from an object to be measured with an infrared sensor cooled through a scanning optical system, comprising an image of the sensor itself coming from the infrared sensor and an infrared sensor reflected from the scanning optical system. A step of obliquely arranging an optical filter having an arbitrary transmittance, which partially reflects an image and transmits the rest, in the optical path of the scanning optical system and the infrared sensor, and the image reflected by the optical filter is transmitted to the infrared sensor. A step of arranging a surface having a low reflectance in the reflection optical path so as not to return, and the narcissus generated when the image of the infrared sensor is reflected by the scanning optical system and again enters the infrared sensor is transmitted by the optical filter. An infrared imaging method characterized by being reduced in proportion to the rate. 2. An infrared imaging device for detecting infrared radiation from an object to be measured by an infrared sensor cooled through a scanning optical system, comprising: an image of the sensor itself coming from the infrared sensor; and an infrared sensor reflected from the scanning optical system. An optical filter having an arbitrary transmittance, which partially reflects an image and transmits the rest, is obliquely arranged in the optical path of the scanning optical system and the infrared sensor, and the image reflected by the optical filter is transmitted to the infrared sensor. It has a surface with a low reflectance arranged in the reflection optical path so as not to return, and the image of the infrared sensor is reflected by the scanning optical system, and the narcissus generated by entering the infrared sensor again is transmitted by the optical filter. An infrared imaging device characterized by being reduced in proportion to the rate.