CN110989060B - A light trap for absorbing and suppressing laser stray light - Google Patents
A light trap for absorbing and suppressing laser stray light Download PDFInfo
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- CN110989060B CN110989060B CN201911203479.8A CN201911203479A CN110989060B CN 110989060 B CN110989060 B CN 110989060B CN 201911203479 A CN201911203479 A CN 201911203479A CN 110989060 B CN110989060 B CN 110989060B
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- 238000010521 absorption reaction Methods 0.000 claims abstract description 30
- 230000001629 suppression Effects 0.000 claims abstract description 13
- 230000003287 optical effect Effects 0.000 claims description 24
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 7
- XDDAORKBJWWYJS-UHFFFAOYSA-N glyphosate Chemical compound OC(=O)CNCP(O)(O)=O XDDAORKBJWWYJS-UHFFFAOYSA-N 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 2
- 238000004364 calculation method Methods 0.000 claims description 2
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 239000011651 chromium Substances 0.000 claims description 2
- 239000011521 glass Substances 0.000 description 11
- 238000000034 method Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 238000002834 transmittance Methods 0.000 description 4
- 238000001514 detection method Methods 0.000 description 3
- 230000002401 inhibitory effect Effects 0.000 description 3
- 230000005764 inhibitory process Effects 0.000 description 3
- 238000004891 communication Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000003071 parasitic effect Effects 0.000 description 2
- 230000002745 absorbent Effects 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 238000007743 anodising Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000002310 reflectometry Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000002966 varnish Substances 0.000 description 1
Classifications
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/12—Reflex reflectors
- G02B5/122—Reflex reflectors cube corner, trihedral or triple reflector type
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/003—Light absorbing elements
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Elements Other Than Lenses (AREA)
Abstract
本发明公开了一种用于吸收抑制激光杂散光的光陷阱。该光陷阱包括反射体，反射体上开设有一个截面为锥形的反射腔；反射腔对入射光的吸收率为ε＞95％；反射腔的锥度为2α；其中，8°＜α≤16.36°；反射体的杂光抑制比为：nmax为反射腔对光的最大反射次数。本发明使得杂光的抑制比可达到1E‑7以上，符合了当前高灵敏度系统对杂光抑制能力的要求。
The present invention discloses a light trap for absorbing and suppressing laser stray light. The light trap comprises a reflector, on which a reflective cavity with a conical cross section is provided; the absorption rate of the reflective cavity to incident light is ε>95%; the taper of the reflective cavity is 2α; wherein 8°<α≤16.36°; the stray light suppression ratio of the reflector is: n max is the maximum number of reflections of light by the reflection cavity. The present invention enables the stray light suppression ratio to reach above 1E-7, which meets the requirements of the current high-sensitivity system for stray light suppression capability.
Description
Technical Field
The invention relates to an optical trap for absorbing and inhibiting laser stray light, which can be used in active laser detection optical systems such as laser communication, laser radar and the like to inhibit and reduce the interference influence of emitted laser on a detector and improve the receiving and transmitting isolation of the active laser detection optical systems.
Background
The laser power emitted by an active laser detection system (such as a laser communication system, a laser radar system and the like) is much higher than the received laser power, and the ratio of the emitted laser power to the received laser power of some high-sensitivity systems can be even as high as 10 10 orders of magnitude. Such high power emitted laser beams cause stray light to easily drown out the received light power, making the system not work properly. A common stray light path of the emitted laser beam is shown in fig. 1. Some energy of the laser emitted by the emission channel is transmitted to the mechanical wall of the structure through the spectroscope, wherein a part of the light is scattered by the mechanical wall, and reaches the receiving channel through the spectroscope to form stray light. The general way to reduce this stray light is to treat the machine wall with stray light, which is usually done by 1) black anodising, 2) spraying a varnish, 3) sticking black velvet etc. The essence of these stray light treatment methods is to increase the absorptivity of the mechanical wall, but the stray light suppression ratio (the ratio of the outgoing light energy to the incoming light energy) of these methods is difficult to reach the order of 1E-4, and it is difficult to satisfy the requirement of the high sensitivity system for the stray light suppression capability.
Disclosure of Invention
In order to solve the problem that the stray light suppression ratio (the ratio of the emergent light energy to the incident light energy) of the existing stray light eliminating treatment method in the background technology is difficult to reach 1E-4 level and difficult to meet the requirement of a high-sensitivity system on the stray light suppression capability, the invention provides a light trap for absorbing and suppressing laser stray light, the stray light suppression ratio of the light trap can be better than 1E-7 level, and the stray light caused by laser emission can be greatly reduced.
The specific technical scheme of the invention is as follows:
The invention provides a light trap for absorbing and inhibiting laser stray light, which comprises a reflector, wherein the reflector is provided with a reflecting cavity with a conical section;
the absorptivity epsilon of the reflector for each reflection of incident light is more than 95%;
the taper of the reflecting cavity is 2 degrees, wherein 8 degrees < alpha is less than or equal to 16.36 degrees;
The stray light suppression ratio of the reflector is: n max is the maximum number of reflections of light by the reflective cavity.
Further, the reflective cavity has two forms:
the first is that the reflecting cavity is a conical cavity.
The second is that the reflecting cavity is composed of two inclined planes which are intersected and have the same inclination angle, and the inclination angle of the inclined planes is alpha.
Further, the specific calculation formula of the maximum reflection number n max of the light by the reflecting cavity is that n max = roundup (90/alpha-0.5), wherein roundup () is an upward rounding function.
Further, the optical trap has two forms:
1. The reflector is made of metal aluminum materials, the surface of a reflecting cavity of the reflector is polished to be a mirror surface, the roughness root mean square value is less than 3nm, an absorption film layer is plated on the surface of the reflecting cavity, and the absorption film layer is a chromium plus medium antireflection film.
2. The reflector is made of colored absorption glass, the internal transmittance of the colored absorption glass in each millimeter of working wavelength is less than 0.01%, the surface of a reflecting cavity of the reflector is polished to be a mirror surface, the roughness root mean square value of the mirror surface is less than 3nm, and an antireflection film is plated on the surface of the reflecting cavity.
Further, the reflector is formed by two wedge-shaped pieces.
The beneficial effects of the invention are as follows:
1. The light trap provided by the invention adopts a structure of combining the reflecting cavity and the absorbing film layer, the incident laser is reflected in the reflecting cavity for a plurality of times, and the absorption rate is very high, so that the inhibition ratio of stray light can reach more than 1E-7, and the requirement of the current high-sensitivity system on the stray light inhibition capability is met.
2. The optical trap provided by the invention only comprises the reflector with the reflecting cavity and the absorption film layer, has a simple structure, is easy to process and manufacture, and is utilized and popularized.
3. The reflection cavity structure adopted by the optical trap provided by the invention ensures that the angle of emergent stray light is fixed no matter how much the incident angle of laser in the reflection cavity is, and ensures that the emergent stray light can still deviate from a receiving view field under the condition of mounting errors.
Drawings
FIG. 1 is a diagram of a typical stray light path of an emitted laser beam;
FIG. 2 is a schematic diagram of an optical trap in the case of a conical reflective cavity according to the present invention;
FIG. 3is a schematic diagram of the structure of an optical trap in the case of two inclined planes in the reflective cavity of the present invention;
FIG. 4 is an absorption rate curve of an absorbent film of the present invention;
Fig. 5 is a diagram of the path of light within an optical trap according to the present invention.
The reference numerals are as follows:
1-reflector, 2-reflecting cavity, 3-inclined plane, 4-wedge.
Detailed Description
To make the objects, advantages and features of the present invention more apparent, a light trap for absorbing and suppressing stray light of laser light is described in further detail below with reference to the drawings and the detailed description. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are not to scale precisely, but merely for the purpose of facilitating and clearly aiding in the description of the embodiments of the invention, and that the structures shown in the drawings are often part of actual structures.
As shown in fig. 2 and 3, the optical trap comprises a reflector 1, wherein a reflecting cavity 2 with a conical section is arranged on the reflector 1, and the conical degree of the reflecting cavity 2 is 2α. Wherein, the angle alpha is 8 degrees and less than or equal to 16.36 degrees, the absorptivity epsilon of the reflector 1 for each reflection of incident light is more than 95 percent, the reflecting cavity 2 has two forms, namely, 1, the reflecting cavity is an integral conical cavity, 2, the reflecting cavity is composed of two inclined planes 3 which are intersected and have the same inclined angle, and the inclined angle of the inclined planes 3 is alpha. Form 1 is more in line with the requirements of the optical device and form 2 is more convenient to process and manufacture.
The light trap absorbs part of light energy when light is incident, the light energy is absorbed in the reflecting cavity of the light trap for multiple times through multiple times of reflection, and finally the emergent light energy is far smaller than the incident light energy. (the reflector is formed by two wedge-shaped pieces 4 in the figure, a reflecting cavity 2 is formed by splicing the two wedge-shaped pieces, see figure 3, or a reflecting cavity 2 can be directly machined on a reflector, see figure 2)
There are two implementations of the reflector:
First, the reflector 1 is made of metal aluminum, the surface of the reflecting cavity 2 is polished to be a mirror surface (the roughness root mean square value is smaller than 3 nm), and the surface of the reflecting cavity 2 is plated with an absorption film layer (not shown in the figure) for the laser wavelength, and the absorption rate of the absorption film layer at the working wavelength is larger than 90%. When laser is incident on the surface of the reflecting cavity, part of laser energy is absorbed by the absorption film layer, and the absorption rate epsilon of the absorption film layer at a single wavelength can reach more than 95%. For example, the reflector is made of polished aluminum material, and the absorption film layer of the medium antireflection film is plated on the inner surface of the reflecting cavity, and the absorption rate of the absorption film layer is shown in figure 3.
Second, the reflector 1 is made of colored absorption glass, and the transmittance of the colored absorption glass is less than 0.01% in each millimeter of the working wavelength. The surface of the reflecting cavity 2 is polished to a mirror surface (the roughness root mean square value is smaller than 3 nm), the surface of the reflecting cavity 2 is plated with a dielectric antireflection film aiming at the working wavelength, the antireflection film has the function of reducing the reflection on the surface of the reflecting surface, so that more light enters the colored absorption glass and is absorbed by the colored absorption glass, and the transmittance of the antireflection film at the working wavelength is larger than 99.5%. For example, for the laser of 1550nm wave band, the reflector adopts a Schottky KG5 colored absorption glass material, the surface of the KG5 colored absorption glass reflector is plated with an antireflection film, the reflectivity of the surface of the reflector in 1550nm wave band is less than 0.5%, the rest 99.5% of energy enters KG5 glass, the internal transmittance of 1550nm laser in KG5 glass is only 4.25e-5/mm, and the light energy entering the glass is almost completely absorbed.
The two schemes of the reflector have the advantages that the first scheme adopts metal aluminum materials and has strong processability, and the second scheme has higher absorptivity and stronger parasitic light inhibition capability.
The light beam is reflected many times in the reflection cavity, and the incident angles of the first, second and third times are respectively:
A1=90°-α (1)
A2＝180°-(90°-A1)-2α-90°=90°-3α (2)
A3＝180°-(90°-A2)-2α-90°=90°-5α (3)
······
An＝180°-(90°-An-1)-2α-90°=90°-(2n-1)α (4)
Wherein when A n >0, i.e., n < (45/alpha + 0.5), the light beam propagates into the reflective cavity of the optical trap, and when A n <0, i.e., n > (45/alpha + 0.5), the light beam begins to propagate out of the reflective cavity of the optical trap.
When 90 degrees+A n is less than or equal to 2α, namely (2n+1α is more than or equal to 180 degrees, the reflected light beam does not intersect the opposite reflecting surface any more, and the light beam exits from the optical trap, so that the maximum reflection times can be calculated as follows:
nmax=roundup(90/α-0.5) (5)
wherein roundup () is an upward rounding function.
The emergent angle is as follows:
β=180°-2nmaxα (6)
The angle alpha is designed to be 1, as many as possible, to absorb more light energy, and generally the number of reflections is greater than 6, 2, the angle of the outgoing light deviates from the receiving field of view theta of the receiving light path, and 3, to meet a certain size of the opening of the reflecting cavity, alpha cannot be too small, which would cause too long a length of the light trap, and generally alpha should be greater than 8 deg.. The constraints for obtaining α are therefore:
The receiving field of view of the receiving optical path is generally within 3 °, and the design constraint condition of the angle α obtained by the above method is:
8°<α≤16.36° (8)
Defining the stray light suppression ratio of the optical trap as the ratio of the light energy of the emergent optical trap to the light energy of the incident optical trap, the stray light suppression ratio of the optical trap is:
Examples of the invention
According to the value range requirement of the angle alpha of the formula (8), alpha=14°. The reflector consists of two wedge-shaped pieces made of aluminum, the surface of the reflecting cavity is polished into a mirror surface (roughness is less than 3 nm) by metal aluminum, an absorption film layer is plated on the surface of the reflecting cavity, and the absorption rate of the absorption film layer at 1550nm is 97.2%. When the laser enters the optical trap, the traveling path of the laser is shown in fig. 5. And (3) calculating according to the formula (7) to obtain the total reflection times of 6, wherein the total reflection times are consistent with the ray tracing result. The light energy of each time the light beam strikes the absorption surface is absorbed by 97.2%, and the energy of the emergent light trap after 6 times of absorption is as follows:
The parasitic light suppression ratio of the light trap is 4.8E-10.
Finally, it should be noted that the above description is only illustrative of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any changes and modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the appended claims.
Claims (4)
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911203479.8A CN110989060B (en) | 2019-11-29 | 2019-11-29 | A light trap for absorbing and suppressing laser stray light |
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| CN201911203479.8A CN110989060B (en) | 2019-11-29 | 2019-11-29 | A light trap for absorbing and suppressing laser stray light |
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| CN110989060B true CN110989060B (en) | 2025-02-11 |
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| CN112130319B (en) * | 2020-09-28 | 2023-02-28 | 中国工程物理研究院激光聚变研究中心 | Ultrahigh-flux laser beam trap and manufacturing method thereof |
| CN112129330B (en) * | 2020-10-13 | 2025-02-07 | 中国科学院长春光学精密机械与物理研究所 | Light field information coupler |
| CN114243451B (en) * | 2021-11-26 | 2024-04-30 | 苏州创鑫激光科技有限公司 | Semiconductor pump source and fiber laser |
| CN118549321A (en) * | 2024-07-29 | 2024-08-27 | 中国计量大学 | Particle counter |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103487144A (en) * | 2013-08-29 | 2014-01-01 | 中国科学院长春光学精密机械与物理研究所 | Double-grating beam splitting system packaging structure stable in stray light eliminating ability |
| CN211148969U (en) * | 2019-11-29 | 2020-07-31 | 中国科学院西安光学精密机械研究所 | An Optical Trap for Absorption and Suppression of Laser Stray Light |
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| JP2006504116A (en) * | 2001-12-14 | 2006-02-02 | ディジタル・オプティクス・インターナショナル・コーポレイション | Uniform lighting system |
| WO2010124204A2 (en) * | 2009-04-24 | 2010-10-28 | Light Prescriptions Innovators, Llc | Photovoltaic device |
| DE102011107581A1 (en) * | 2011-07-16 | 2013-01-17 | Gangolf Jobb | Solar panel for driving thermal engine, has radiation receiver which absorbs radiation completely and transforms in heat energy, where device is provided for concentrating sunlight on radiation receiver |
| CN108169187B (en) * | 2017-12-15 | 2024-05-10 | 中国科学院西安光学精密机械研究所 | Test cavity for testing point source transmittance |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103487144A (en) * | 2013-08-29 | 2014-01-01 | 中国科学院长春光学精密机械与物理研究所 | Double-grating beam splitting system packaging structure stable in stray light eliminating ability |
| CN211148969U (en) * | 2019-11-29 | 2020-07-31 | 中国科学院西安光学精密机械研究所 | An Optical Trap for Absorption and Suppression of Laser Stray Light |
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