CN111238659A

CN111238659A - Cold screen and refrigeration type infrared detector with stray light inhibiting function

Info

Publication number: CN111238659A
Application number: CN202010066302.4A
Authority: CN
Inventors: 张杨文; 沈星; 王立保
Original assignee: Wuhan Gaoxin Technology Co Ltd
Current assignee: Wuhan Gaoxin Technology Co Ltd
Priority date: 2020-01-20
Filing date: 2020-01-20
Publication date: 2020-06-05
Anticipated expiration: 2040-01-20
Also published as: CN111238659B

Abstract

The invention relates to a cold shield and a refrigeration type infrared detector with the function of suppressing stray light, wherein a light through hole is arranged on one side of the cold shield, light blocking rings are arranged on the inner wall of the cold shield, each light blocking ring is provided with a chamfer inclined plane, the included angle between the lower end of the chamfer inclined plane and the end face of the light blocking ring is α, the included angle between the connecting line of the tip vertex at the lower end of the chamfer inclined plane and the upper end point of a detector focal plane and the focal plane is β, the end face of the light blocking ring is parallel to the focal plane, the focal plane rotates clockwise by 0-180 degrees to be positive, and the focal plane rotates anticlockwise by 0-180 degrees to be negative, wherein α is less than or equal to β.

Description

Cold screen and refrigeration type infrared detector with stray light inhibiting function

Technical Field

The invention relates to the technical field of infrared thermal imaging refrigeration technology, in particular to a cold shield with a stray light inhibiting function and a refrigeration type infrared detector.

Background

The detection of the background and the target by the refrigeration type infrared detector is realized by analyzing the background, the radiance of the target radiation and the temperature difference. In a refrigeration detector system, the detector assembly operates at a relatively low refrigeration temperature, which is about 77K. The infrared detector assembly is an infrared radiation energy converter, and is mainly used for converting received infrared radiation into electric energy, heat energy and other forms which are convenient to measure or identify. The stray light refers to other non-target imaging light rays radiated onto the detector or the imaging surface, and target light rays reaching the detector through an abnormal transmission path, besides the imaging light rays of the target in the infrared detection imaging system.

However, the surface temperature of the target light source detected by the detector system is far higher than the refrigeration temperature of the detector assembly, part of infrared radiation generated by the detector system is reflected once by the inner wall of the light blocking ring of the cold shield and directly reaches the focal plane, and the external stray light has great negative influence on the signal-to-noise ratio while forming background radiation noise on the focal plane of the system, so that the signal-to-noise ratio, the contrast of an image plane and a modulation transfer function of the detected target are reduced, the gradation of the whole image plane is reduced, the definition is poor, the energy distribution is disordered, and even stray light spots are formed; the detected target signal is completely annihilated in the stray light background, the system cannot identify the target, or a false signal is formed on a system detector due to uneven image plane stray light distribution, so that the system detects a false target, and even the whole detection system fails. In the prior art, the problem of stray light cannot be effectively solved, so that a cold screen and a refrigeration type infrared detector with a function of suppressing the stray light are very necessary.

Disclosure of Invention

One of the purposes of the invention is to provide a cold shield with a function of suppressing stray light, and to solve the technical problem that the stray light has great adverse effect on the infrared radiation parameters of a target light source detected by an infrared detector in the prior art.

The technical scheme for achieving one of the purposes of the invention is that the cold shield with the function of suppressing stray light is characterized in that a light through hole is formed in one side of the cold shield, at least 1 light blocking ring is arranged on the inner wall of the cold shield, an annular chamfer inclined plane is arranged on each light blocking ring, the included angle between the lower end of each chamfer inclined plane and the end face of each light blocking ring is α, the included angle between the connecting line of the vertex of the tip of the lower end of each chamfer inclined plane and the upper end point of the focal plane of the detector body and the focal plane is β, the end face of each light blocking ring is parallel to the focal plane, clockwise rotation of 0-180 degrees in the direction of the end face of each light blocking ring or the focal plane is positive, and counterclockwise rotation of 0-180 degrees in the direction of the end face of each light blocking.

Further, the number of the light blocking rings is 3, each light blocking ring is provided with a chamfer inclined plane, each chamfer inclined plane is a first inclined plane, and each first inclined plane faces the light through hole.

Furthermore, the number of the light blocking rings is 3, each light blocking ring is provided with a chamfer inclined plane, wherein 2 chamfer inclined planes are first inclined planes facing the light through hole, and the other 1 chamfer inclined plane is a second inclined plane back to the light through hole.

Furthermore, the number of the light blocking rings is 3, each light blocking ring is provided with a chamfer inclined plane, the chamfer inclined plane is a second inclined plane, and each second inclined plane faces away from the light through hole.

Further, a blackening film is coated on the inner wall of the cold shield.

Further, the material of the light blocking ring is nickel-cobalt alloy.

Furthermore, the number of the light blocking rings is multiple.

The technical scheme for realizing one purpose of the invention is as follows: the invention provides a cold shield with a function of inhibiting stray light, which has the following advantages:

1. the inner wall of the light blocking ring is chamfered to shield stray light on the inner wall;

2. by designing α to be not more than β, external light reflected once by any point on the chamfer inclined plane can not directly reach the focal plane due to the blockage of the chamfer inclined plane, so that the interference of stray light is further thoroughly inhibited by the chamfer treatment, the stray light reaching the focal plane through the once reflection of the inner wall of the light barrier ring is completely shielded, and the negative influence of the once reflection of the stray light on the signal to noise ratio of the inner wall of the light barrier ring can be greatly reduced.

The invention also aims to provide a refrigeration type infrared detector.

The second technical scheme for realizing the aim of the invention is as follows: the utility model provides a refrigeration type infrared detector, includes detector body and a cold screen that has the stray light of suppression function, be equipped with the focal plane on the detector body, the focal plane is to the light-emitting window of cold screen.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings. The detailed description of the present invention is given in detail by the following examples and the accompanying drawings.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:

fig. 1 is a schematic structural diagram of a cold shield having a function of suppressing stray light according to embodiment 1 of the present invention;

FIG. 2 is a partial enlarged view of the limit light path of stray light at three points N1, N2 and N3 in the cold shield with the function of suppressing stray light provided by FIG. 1;

FIG. 3 is a schematic diagram of a reflection light path along an inclined surface of an inner wall of a light blocking ring in the cold shield with the function of suppressing stray light provided in FIG. 1;

fig. 4 is a schematic view of the reflection light path along the inclined plane of the inner wall of the light blocking ring in the cold shield with the function of suppressing stray light provided in fig. 1, and three points N1, N2, and N3 are respectively connected to the upper edge of the focal plane;

FIG. 5 is a schematic diagram of the inclined plane at N3 facing the focal plane in the cold shield with the function of suppressing stray light provided by FIG. 1;

fig. 6 is a schematic structural diagram of a cold shield (provided with a detector outer wall casing outside) with a function of suppressing stray light of external parts according to embodiment 2 of the present invention;

FIG. 7 is a light path diagram of stray light at two extreme positions in the cold shield provided in FIG. 1 and having the function of suppressing stray light of external parts;

fig. 8 is a light path diagram of stray light at one extreme position in a cold shield having a function of suppressing stray light of external parts according to embodiment 3 of the present invention.

In the drawings, the components represented by the respective reference numerals are listed below:

1. cooling the screen; 11. a light blocking ring; 111. a first inclined plane; 112. a second inclined plane; 12. a light through hole; 13. a shoulder portion; 2. a probe body; 21. a focal plane; 3. a first optical path; 4. a second optical path; 5. a third optical path; 6. a detector outer wall housing; 61. a window piece; 7. a fourth optical path; 8. and a fifth light path.

Detailed Description

The principles and features of the present invention are described below in conjunction with the accompanying fig. 1-5, which are provided as examples to illustrate the invention and not to limit the scope of the invention. The invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or intervening components may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Example 1

As shown in embodiment 1 of fig. 1 to 5, the present invention provides a refrigeration-type infrared detector, which includes a detector body 2 and a cold shield 1 having a function of suppressing stray light, wherein a focal plane 21 is disposed on the detector body 2, and the focal plane 21 faces a light outlet of the cold shield 1.

The detector comprises a cold screen 1, a light through hole 12 is arranged on one side of the cold screen 1, at least 1 light blocking ring 11 is arranged on the inner wall of the cold screen 1, an annular chamfer inclined plane is arranged on each light blocking ring 11, the included angle between the lower end of the chamfer inclined plane and the end surface of the light blocking ring 11 is α, the included angle between the connecting line of the tip top of the lower end of the chamfer inclined plane and the upper end of a focal plane 21 of the detector body 2 and the focal plane 21 is β, the end surface of the light blocking ring 11 is parallel to the focal plane 21, clockwise rotation of 0-180 degrees is positive in the direction of the end surface of the light blocking ring 11 or the focal plane 21, counterclockwise rotation of 0-180 degrees is negative in the direction of the end surface of the light blocking ring 11 or the focal plane 21, wherein α is not more than β.

The reflection of light by the inner wall (rough surface) of the cold shield 1 is generally regarded by default as diffuse reflection at present.

The cold shield with the function of suppressing stray light is provided in the above embodiment, and has the following advantages:

1. the inner wall of the light blocking ring 11 is chamfered to shield stray light on the inner wall;

2. by designing α to be not more than β, external light reflected once by any point on the chamfer can not directly reach the focal plane due to the blockage of the chamfer, so that the interference of stray light is further thoroughly inhibited by the chamfer, the stray light reaching the focal plane through the once reflection of the inner wall of the light barrier ring 11 is completely shielded, and the negative influence of the once reflection of the stray light on the inner wall of the light barrier ring 11 on the signal to noise ratio can be greatly reduced.

In particular, as shown in FIGS. 1-2, the detector configurations referred to in this patent are focal plane, cold shield, window, and outer member. BF is the focal plane and receives infrared thermal radiation. N1, N2, N3 are respectively arbitrary points on the inner wall of the light-blocking ring 11. The connection limit light paths AN1, N1B, AN2, N2B, AN3 and N3B are stray light path diagrams which reach a focal plane BF by primary reflection from the outside of the cold shield through the inner wall of the light blocking ring of the cold shield. AN1 to N1B are first optical paths, AN2 to N2B are second optical paths, and AN3 to N3B are third optical paths.

Fig. 2 is a partially enlarged image of the inner wall of the light-blocking ring in fig. 1, and it can be seen that the external light reflected once by the points N1 and N2 cannot directly reach the focal plane. While the external light ray reflected once by point N3 can directly reach the focal plane.

3-4, the chamfer angles of the inner wall of the known light barrier ring are α 1, α 2, α 3, respectively, the auxiliary lines parallel to the inner wall of the light barrier ring are made at points N1, N2, N3, the first two auxiliary lines are not intersected with the focal plane, the last one is reached, as shown in the figure, any one of the definitions α 1, α 2, α 3 … … is α i, where i is 1, 2, 3 … …

Connecting lines respectively connecting the vertex of the chamfer tip and the vertex B of the focal plane form included angles of β 1, β 2 and β 3 with the focal plane respectively, and any one of β 1, β 2 and β 3 … … is defined as β i, wherein i is 1, 2 and 3 … …

When the chamfer angle of the inner wall of the light-blocking ring is small enough, that is, the angle of α i is small enough, and the passing point Ni is taken as an auxiliary line parallel to the inner wall of the light-blocking ring at the moment and is not intersected with the focal plane BF, the external light ray can not directly reach the focal plane through the primary reflection of the inner wall of the light-blocking ring.

Preferably, the number of the light-blocking rings 11 is 3, each light-blocking ring 11 is provided with a chamfer inclined plane, the chamfer inclined plane is a first inclined plane 111, and each first inclined plane 111 faces the light-passing hole 12. Clockwise rotation of 0-180 degrees in the vertical direction is positive, and anticlockwise rotation of 0-180 degrees in the vertical direction is negative.

Therefore, the inner wall of the light-blocking ring 11 can be completely shielded from the external primary reflection stray light only by controlling the chamfer angle of the light-blocking ring 11 to make α i less than or equal to β i.

By designing the first inclined surface 111 to face the light passing hole 12, most of the rays of stray light can be reflected back or out of the focal plane 21.

Preferably, as shown in fig. 5, the number of the light-blocking rings 11 is 3, each light-blocking ring 11 is provided with a chamfer inclined plane, 2 of the chamfer inclined planes are first inclined planes 111 facing the light-passing hole, and the other 1 of the chamfer inclined planes is a second inclined plane 112 facing away from the light-passing hole, because the other 1 of the chamfer inclined planes are second inclined planes 112 facing away from the light-passing hole and rotated counterclockwise by 0-180 degrees in the vertical direction as a negative, α 3 is less than 0, that is, the light-blocking rings 11 are turned in the chamfer direction, so that most of stray light rays can only be reflected between the light-blocking rings 11 and cannot reach a focal plane, and the inner wall of the light-blocking ring can be ensured to completely shield stray light reflected once from the outside.

Preferably, the number of the light-blocking rings 11 is 3, each light-blocking ring 11 is provided with a chamfer inclined surface, the chamfer inclined surface is a second inclined surface 112, and each second inclined surface 112 faces away from the light-transmitting hole 12, so that primary stray light reflected to a focal plane through the inner wall of the light-blocking ring is completely shielded, the performance of the detector is improved, and the effect is optimal at this time.

Preferably, the inner wall of the cold shield 1 is coated with a blackening film.

The inner wall of the cold shield 1 is coated with the blackening film, the blackening film can be made of paint, and the blackening film has the function of absorbing a large amount of stray light radiation, so that the shielding function of the cold shield is further improved.

Preferably, the material of the light blocking ring 11 is nickel-cobalt alloy, which has extremely strong anti-rust and corrosion resistance.

Preferably, the number of the light-blocking rings 11 can be designed to be plural.

The specific working principle and the using method of the embodiment 1 of the invention are as follows:

1. in order to completely shield the primary reflected stray light on the inner wall of the light blocking ring 1, the size of the chamfer angle needs to be correspondingly adjusted, so that α i is less than or equal to β i;

2. by changing the chamfer angle of the light barrier ring 1, the primary stray light reflected to the focal plane through the inner wall of the light barrier ring 11 is completely shielded, and the performance of the detector body 2 is improved.

Example 2

As shown in fig. 6 to 7, embodiment 2 of the present invention provides a refrigeration type infrared detector, including a detector body 2, a cold shield 1, and a detector outer wall casing 6, where the detector outer wall casing 6 is disposed on the periphery of the cold shield 1, the detector body 2 and the cold shield 1 are coaxially disposed, the detector body 2 is located at a light exit on the right side of the cold shield 1, a focal plane 21 is disposed on the detector body 2, the focal plane 21 is opposite to the light exit, and one end of the detector outer wall casing 6 is provided with a window sheet 61.

As shown in fig. 6-7, an annular shoulder 13 is disposed at one end of the cold shield 1, a light through hole 12 is disposed on the shoulder 13, a lower end point of the light through hole 12 is set to be a point C, and a lower end point of the shoulder 13 is set to be a point M. The upper end point of the focal plane 21 is a point B, the lower end point of the focal plane 21 is a point F, and the focal plane 21 is BF to receive infrared heat radiation. In the main sectional view, AN and CM are both ends of the shoulder 13 of the cold shield 1, and AC is the light passing hole 12 of the cold shield 1.

Connecting the limit point B of the focal plane 21 with the limit point C of the light-transmitting hole 12 of the cold shield 1, making a dotted line BC and extending to the louver, intersecting the louver at a point G, taking GB as the limit reflected light path and the normal line thereof, and making an incident light path GQ, Q being a point on the surface of the external member. And a limit stray light path is formed by the QG and the GB.

A normal is taken perpendicular to CM across the mid-point of CM, normal intersecting the louver at point G ', connecting G ' C and extending to the focal plane at point B ', connecting G ' M and extending to a point Q ' on the outer member surface. Q 'G' and G 'B' form another limit stray light path. QG to GB are the fourth optical path 7, and Q 'G' to G 'B' are the fifth optical path 8.

Infrared stray light radiation emitted by the QQ 'on the surface of the outer wall shell 6 of the detector with the temperature far higher than the refrigeration temperature can directly reach the focal plane 2 through primary reflection at the window pieces GG', the reflectivity of the window pieces can be approximate to 5%, and however 5% of the primary reflected stray light can generate great adverse effect on the signal-to-noise ratio.

Example 3

As shown in FIG. 8, on the basis of FIG. 7, after widening the cold shield shoulders CM, AN, BC is connected and extended to intersect the window G with a perpendicular GO perpendicular to CM, GM 'and GB are symmetrical about this perpendicular, and M' is on CM.

In summary, the length of CM is only required to be greater than or equal to CM ', that is CM ≧ CM ' (widening the shoulder 13 to ensure CM ≧ CM '), in order for the shoulder to block the primary reflected stray light generated by the thermal radiation of the outer part.

When CM is larger than or equal to CM', the cold shield structure can shield all stray light generated by external parts and reaching a focal plane through primary reflection, so that the performance of the detector is improved.

Therefore, it can be seen that the specific scheme shown in fig. 8 is a preferred embodiment provided by the present invention, and can be summarized as follows:

the detector is characterized in that a shoulder 13 is arranged at one end of the cold shield 1, an annular shoulder 13 is arranged at one end of the cold shield 1, a light through hole 12 is arranged on the shoulder 13, a lower end point of the light through hole 12 is set to be a point C, a lower end point of the shoulder 13 is a point M, an upper end point of the focal plane 21 is a point B, the point BC is connected and extended to intersect with a window sheet 61 located at one end of an outer wall shell 6 of the detector, an intersecting point G is set to be a point G, a perpendicular line GO is perpendicular to the CM after passing through the point G, a straight line GM 'is formed after passing through the point G, the GM' and the GB are symmetrical about the perpendicular line GO, and the point M.

In the above embodiment, the shoulder 13 is designed at the light through hole 12 of the cold shield 1 to shield stray light generated by the outer wall shell of the infrared detector; by widening the shoulder part 13 of the cold shield 1 and ensuring that CM is more than or equal to CM', the primary reflection stray light emitted by heat radiation at any point on the outer wall shell 6 of the detector cannot directly reach a focal plane due to the blocking of the shoulder part 13, so that the interference of the stray light is further thoroughly inhibited by widening the shoulder part 13 of the cold shield 1, the stray light reaching the focal plane by the primary reflection of the outer wall shell 6 of the detector through the window sheet 61 is completely shielded, and the negative influence of the primary reflection stray light of the window sheet 61 on the signal to noise ratio can be greatly reduced.

Preferably, as shown in fig. 6 to 8, the light-passing hole 12 is located at the center of the shoulder 13 to ensure that the widths of the annular shoulder 13 are the same, which is more convenient for the cold shield 1 structure to shield the stray light reaching the focal plane through primary reflection of the heat radiation generated by the outer wall housing 6 of the detector, thereby improving the performance of the detector.

The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner; the present invention may be readily implemented by those of ordinary skill in the art as illustrated in the accompanying drawings and described above; however, those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the present invention without departing from the scope of the invention as defined by the appended claims; meanwhile, any changes, modifications, and evolutions of the equivalent changes of the above embodiments according to the actual techniques of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. The cold screen with the stray light inhibiting function is characterized in that a light through hole (12) is formed in one side of the cold screen (1), at least 1 light blocking ring (11) is arranged on the inner wall of the cold screen (1), an annular chamfer inclined plane is arranged on each light blocking ring (11), an included angle between the lower end of each chamfer inclined plane and the end face of each light blocking ring (11) is α, an included angle between a connecting line of the top end of the lower end of each chamfer inclined plane and the upper end of a focal plane (21) of the detector body (2) and the focal plane (21) is β, the end face of each light blocking ring (11) is parallel to the focal plane (21), clockwise rotation of 0-180 degrees in the direction of the end face of each light blocking ring (11) or the direction of the focal plane (21) is positive, counterclockwise rotation of 0-180 degrees in the direction of the end face of each light blocking ring (11) or the direction of the focal plane (21) is negative, and.

2. A cold shield with stray light suppression according to claim 1, wherein the number of said light blocking rings (11) is 3, said chamfered slopes are first slopes (111), and each of said first slopes (111) faces said light passing hole (12).

3. A cold shield with stray light suppression according to claim 1, wherein the number of said light blocking rings (11) is 3, wherein 2 of said chamfered slopes are first slopes (111) facing the light through hole, and the other 1 of said chamfered slopes is second slopes (112) facing away from the light through hole.

4. A cold shield with stray light suppression according to claim 1, wherein the number of said light blocking rings (11) is 3, said chamfered slope is a second slope (112), and each said second slope (112) faces away from the light passing hole (12).

5. A cold shield with stray light suppression according to claim 1, wherein said light blocking rings (11) are provided in a plurality.

6. A cold shield with stray light suppression according to claim 1, wherein the inner wall of the cold shield (1) is coated with a blackening film.

7. A cold shield with stray light suppression according to claim 1, wherein the material of the light blocking ring (11) is nickel-cobalt alloy.

8. A refrigeration type infrared detector is characterized by comprising a detector body (2) and a cold shield (1) with a function of suppressing stray light according to any one of claims 1 to 7, wherein a focal plane (21) is arranged on the detector body (2), and the focal plane (21) faces to a light outlet of the cold shield (1).