JPH0541384Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to an infrared detection element cooling device that is widely used for measuring the temperature and position of objects. This invention relates to a detection element cooling device.

Conventional technology Infrared detection elements are made of materials sensitive to infrared rays, such as germanium, and this detection element has the property of increasing sensitivity and response speed when cooled to an extremely low temperature, for example, around 77K. .

Therefore, infrared detection elements have conventionally been cooled to extremely low temperatures using a Stirling cycle refrigeration system.

This refrigeration system uses a compression piston to compress the helium gas in the compressor, then presses this gas into the cylinder of the regenerator, expands it while passing through the expansion piston, and uses the heat of vaporization to cool the regenerator to an extremely low temperature. (Refer to Publication No. 32268 of 1988).

Problems to be Solved by the Invention In the conventional infrared detection element cooling device, when the expansion piston of the regenerator with infrared detection element and the compression piston of the compressor are driven, they become different sources of vibration.

Therefore, since the vibrations of the compressor and regenerator have different periods, it is recommended to provide an image section directly on the outer cylinder of the vacuum chamber, or to provide an image section indirectly on the outer cylinder through a flexible optical guide. , the vibration period of the image area and that of the infrared detection element no longer match.

Therefore, both do not remain optically stationary, making accurate measurement impossible.

In view of the above circumstances, the object of this invention is to provide an infrared detection element cooling device that can perform accurate measurements.

Means for Solving the Problems This invention connects a cooling head with an infrared detection element built in the vacuum chamber of a Stirling cycle refrigeration system to a regenerator cylinder via a flexible conductor, and a heater is provided in the cooling head. A cooling head is fixed to an outer cylinder of a vacuum chamber, a window is provided on a wall of the vacuum chamber facing the infrared detection element, a vacuum seal is formed on the outside of the wall to seal the window, and the window is sealed. The above object is achieved by an infrared detection element cooling device characterized in that an imaging section is provided apart from the freezing device, one end of a flexible optical guide is connected to the imaging section, and the other end is connected to the vacuum shield section. This is what I am trying to do.

Operation When a Stirling cycle refrigeration system is started and the compression piston and expansion piston are driven, the outer cylinder of the vacuum chamber and the regenerator cylinder vibrate at different periods, but the vibrations of the regenerator cylinder are controlled by the flexible conductor. Since it is absorbed, it is not transmitted to the cooling head.

Therefore, the vibration of the infrared detecting element provided in the cooling head coincides with that of the outer cylinder of the vacuum chamber.

Embodiment An embodiment of this invention will be described with reference to the accompanying drawings, where the same reference numerals have the same names and functions.

A regenerator 3 is disposed in a vacuum chamber 2 surrounded by an outer cylinder 1. This regenerator 3 includes a separate cooling head 8 and a regenerator tube 3a, both of which are 8 and 3.
a is connected via a flexible conductor 30, for example a copper braided wire.

The cooling head 8 is made of copper, and the fixture 8
It is fixed to the cap 1a of the outer cylinder 1 via a.

A heater 8b for adjusting the cooling temperature is provided on the lower surface of the cooling head 8, and an infrared detection element 9 is provided on the upper surface.

This detection element 9 has a wavelength range of 1, for example.
A ~3.8 μm germanium detection element is used.

Inside the cold storage cylinder 3a, an expansion piston 7 is connected to the crank 5 of the crank chamber 4 via a rod 6.
is provided.

An infrared ray through hole 10 is formed in the cap 1a facing the detection element 9.
is closed by a silicon window 11.

A vacuum shield section 12 is provided on the outside of the window 11, and at the center of the shield section 12,
A rear end portion 13a of the flexible optical guide 13 facing the window 11 is fixed. This guide 13 is, for example, an optical fiber, and its rear end 13b is connected to an image section 14, in which a condensing lens 15 and an interference glass plate 16 are arranged in series. ing.

In addition, 17 is a compression piston of a compressor connected to the crank 18, 19 is lubricating oil in the crank chamber 4,
Reference numeral 22 indicates the outlet of the leader line 20, respectively. next,
The operation of this embodiment will be explained.

The image section 14 is fixed and kept stationary so as to face the object to be measured 29, for example, a human body.

When the rotating shaft 26 of the Stirling cycle refrigeration system 25 is rotated and the compression piston 17 is reciprocated, the compression process, that is, the process of compressing the helium gas in the compressor 27 and pressurizing it into the regenerator 3, and the suction process, that is, the process of compressing the helium gas in the regenerator 3, The process of absorbing helium gas into the compressor 27 is repeated.

The helium gas pressurized into the regenerator 3 undergoes a first expansion in the lower part of the cylinder of an expansion piston (not shown), and then enters the expansion piston and undergoes a second expansion.

The heat of vaporization of the helium gas accompanying these expansions causes the cooling head 8 to reach an extremely low temperature, for example, 77K.
At the same time, the infrared detection element 9 is also cooled to an extremely low temperature.

By the way, as mentioned above, when the compression piston 17, expansion piston, etc. of the Stirling cycle refrigeration system 25 operate, vibrations occur, causing the regenerator cylinder 3a and the cap 1a to vibrate at different cycles. but,
This vibration of the cold storage cylinder 3a is absorbed by the flexible conductive wire 30, so that it is not transmitted to the cooling head 8.

Therefore, the cooling head 8 is not affected by the vibration of the cool storage cylinder 3a, and therefore always matches the period of vibration of the cap 1a.

Therefore, since the vibrations of the infrared detection element 9 and the rear end portion 13a of the flexible optical guide are synchronized, both 9 and 13a maintain an optically stationary state.

Further, since the vibration of the cap 1a is absorbed by the flexible optical guide 13, it is not transmitted to the image section 14.

Therefore, the image section 14 does not vibrate and maintains a stationary state.

Since the measurement of the object to be measured is performed in such a stationary state, only the infrared component emitted by the object to be measured 29 is transmitted through the interference glass 16 and the condenser lens 1.
Flexible optical guide 13 through 5
The input signal is inputted to the tip end 13b of the head and outputted from the rear end 13a.

Therefore, only the infrared component is input to the infrared detection element 9, and no noise component is input.

The output of the infrared detection element 9 is amplified by a preamplifier 21, converted into a signal by an A/D converter 31, and recognized by a computer 32.

Effects of the invention As described above, in this invention, the cooling head with an infrared detection element and the regenerator are connected via flexible conductive wires, and the cooling head is fixed to the outer cylinder of the vacuum chamber. is absorbed by the flexible conductor,
It is not transmitted to the cooling head.

Therefore, since the infrared detection element and the outer cylinder of the vacuum chamber vibrate in synchronization, both are in an optically stationary state, allowing precise measurement.

Furthermore, if an imaging section is provided separately from the Stirling cycle refrigeration system and the infrared detection element and the imaging section are connected via a flexible optical guide, the vibrations generated from the refrigeration system are absorbed by the flexible optical guide, and the imaging section is Not communicated to the department.

Therefore, since the imaging section separated from the freezing device measures the object to be measured in a static state without vibration, no vibration component is generated in the imaging section.

Therefore, since only the infrared component is input to the infrared detection element, more accurate measurements can be made. Further, a window is provided on the wall of the vacuum chamber facing the infrared detection element, a vacuum seal is formed on the outside of the wall to cover the window, and the other end of the flexible optical guide is connected to the vacuum seal. This creates a vacuum on both sides of the window.

Therefore, even if the window made of a material that is easily damaged is made thinner, breakage accidents due to differential pressure will not occur, so that the window can be made thinner to improve the transmittance of infrared rays.

Further, the infrared rays from the image area are sequentially transmitted to the guide,
It passes through the vacuum seal, window, and vacuum chamber and reaches the infrared detection element without coming into contact with air.

Therefore, all of the infrared rays reach the infrared detection element without being diffusely reflected by the air, so that detection accuracy can be improved. Furthermore, since the cooling head is provided with a heater, when the cooling temperature is too low, the heater can be driven to warm the cooling head.

Therefore, since the infrared detection element can be maintained at a predetermined temperature, highly accurate detection can be performed.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view showing an embodiment of this invention, and FIG. 2 is an enlarged view of the main part of FIG. 1. 3... Regenerator, 3a... Regenerator cylinder, 8... Cooling head, 9... Infrared detection element, 13... Flexible optical guide, 25... Stirling cycle refrigeration device, 30... Flexible conducting wire.

Claims (1)

[Scope of utility model registration request] A cooling head with an infrared detection element built into the vacuum chamber of a Stirling cycle refrigeration system is connected to a cold storage cylinder via a flexible conductor, a heater is provided to the cooling head, and the cooling head is fixed to the outer cylinder of the vacuum chamber. , a window is provided on a wall of the vacuum chamber facing the infrared detection element, a vacuum seal is formed on the outside of the wall to seal the window, an imaging section is provided apart from the freezing device, and a flexible An infrared detection element cooling device characterized in that one end of an optical guide is connected to the image section and the other end is connected to the vacuum seal section.