CN113189784A - Method for eliminating central bright spot or zero-order diffraction of diffraction optical element by total reflection - Google Patents
Method for eliminating central bright spot or zero-order diffraction of diffraction optical element by total reflection Download PDFInfo
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- CN113189784A CN113189784A CN202110497431.3A CN202110497431A CN113189784A CN 113189784 A CN113189784 A CN 113189784A CN 202110497431 A CN202110497431 A CN 202110497431A CN 113189784 A CN113189784 A CN 113189784A
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- total reflection
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
- G02B27/4233—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive element [DOE] contributing to a non-imaging application
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
- G02B26/0875—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more refracting elements
- G02B26/0883—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more refracting elements the refracting element being a prism
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Abstract
The invention discloses a method for eliminating central bright spots or zero-order diffraction of a diffractive optical element by total reflection, which comprises the following steps: step one, arranging a laser light source, a collimating mirror and a diffraction optical element, so that light of the laser light source forms a light beam after passing through the collimating mirror and is emitted into the diffraction optical element, and imaging light rays and central bright spot light rays are formed through the diffraction optical element; and secondly, arranging a mirror surface behind the diffraction optical element, so that the incident angle between the central bright spot light and the mirror surface is a total reflection angle. The method for eliminating the central bright point or zero-order diffraction of the diffractive optical element by total reflection can eliminate the central bright point light after the total reflection by utilizing the total reflection principle through the arrangement of the mirror surface.
Description
Technical Field
The invention relates to a zero-order diffraction eliminating method, in particular to a method for eliminating a central bright spot or zero-order diffraction of a diffraction optical element by total reflection.
Background
When illuminated by laser light, a Diffractive Optical Element (DOE) produces a diffraction pattern on the screen, projecting the pattern according to a predetermined design. Such patterns often have a bright spot in the center and high energy, which can seriously interfere with the recognition of the pattern if not eliminated, especially in the case of eye safety, limiting the improvement of the pattern brightness.
Therefore, in the prior art, there is patent No. 2017107883663, which is named as a laser projection device with adjustable zero-order diffraction, and discloses that the elimination of zero-order diffraction is realized by adopting an adjustable zero-order suppression unit, and further discloses that the adjustable zero-order suppression unit is a combination of a polarizer and an analyzer, in the suppression process, after the polarization is performed by a linear polarizer, the second zero-order diffracted beam is emitted to a half-wave plate device, then the second zero-order diffracted beam is subjected to optical rotation by the half-wave plate, the polarization direction of the second zero-order diffracted beam is deflected to a certain degree, and the third zero-order diffracted beam is emitted to the analyzer, part of the capability of the third zero-order diffracted beam is absorbed by the linear polarizer, and finally the fourth zero-order diffracted beam is emitted from the adjustable zero-order suppression unit and is projected to a zero-order beam projection region of a target plane, although the above-existing projection device realizes the suppression of the diffracted beam by the adjustable zero-order suppression unit, however, it has only an inhibiting effect and cannot completely eliminate the zero-order diffracted beam, so that the zero-order diffracted beam still exists in the projection process, and bright spots may appear if the pattern brightness is further improved.
Disclosure of Invention
In view of the disadvantages of the prior art, the present invention provides a method for eliminating the central bright point or the zero-order diffraction of a diffractive optical element by total reflection, which can completely eliminate the zero-order diffraction.
In order to achieve the purpose, the invention provides the following technical scheme: a method for eliminating central bright spot or zero order diffraction of a diffractive optical element by total reflection, comprising the steps of:
step one, arranging a laser light source, a collimating mirror and a diffraction optical element, so that light of the laser light source forms a light beam after passing through the collimating mirror and is emitted into the diffraction optical element, and imaging light rays and central bright spot light rays are formed through the diffraction optical element;
and secondly, arranging a mirror surface behind the diffraction optical element, so that the incident angle between the central bright spot light and the mirror surface is a total reflection angle.
As a further improvement of the present invention, the mirror surface in the second step is to eliminate prisms, and the specific mirror surface setting step is as follows:
step two, one mirror surface of the eliminating prism is used as an incidence surface, and the other mirror surface is used as a reflection surface, so that the imaging light and the central bright point light formed by the diffractive optical element in the step one are incident into the eliminating prism from the incidence surface and are emitted from the reflection surface;
and secondly, adjusting and eliminating the placing angle of the prism according to the included angle between the imaging light and the central bright spot light, so that the incident angle between the central bright spot light and the reflecting surface reaches a total reflection angle, and the incident angle between the imaging light and the reflecting surface is smaller than the total reflection angle.
As a further improvement of the present invention, the step of disposing the mirror further includes:
and step two, arranging an adjusting prism behind the reflecting surface, wherein the adjusting prism is the same as the eliminating prism, the reflecting surface of the adjusting prism corresponding to the eliminating prism is used as an incident surface, and the incident surface of the adjusting prism corresponding to the eliminating prism is used as an emergent surface, so that the imaging light enters from the incident surface, is subjected to deviation rectification adjustment, and then is emitted from the emergent surface.
The invention has the advantages that the combined action of the laser light source, the collimating mirror and the diffraction optical element can be effectively utilized through the arrangement of the first step, so that imaging light and central bright spot light are finally formed and output, and then the total reflection principle can be effectively utilized through the arrangement of the second step, so that the central bright spot light can be completely and effectively eliminated, and the problems that the pattern brightness is further improved and bright spots are possibly generated can be avoided.
Drawings
FIG. 1 is a schematic diagram of a prior art laser imaging optical path;
FIG. 2 is a schematic diagram of the optical path of the method of the present invention;
fig. 3 is a schematic diagram of a further optimized optical path of the method of the present invention.
Detailed Description
The invention will be further described in detail with reference to the following examples, which are given in the accompanying drawings.
Referring to fig. 1 to 3, a method for eliminating a central bright point or zero order diffraction of a diffractive optical element using total reflection according to the present embodiment includes the steps of:
step one, arranging a laser light source, a collimating mirror and a diffraction optical element, so that light of the laser light source forms a light beam after passing through the collimating mirror and is emitted into the diffraction optical element, and imaging light rays and central bright spot light rays are formed through the diffraction optical element;
and step two, a mirror surface is arranged behind the diffraction optical element, so that the incident angle between the central bright spot light and the mirror surface is a total reflection angle.
As an improved specific implementation manner, the mirror surface in the second step is to eliminate prisms, and the specific mirror surface setting step is as follows:
step two, one mirror surface of the eliminating prism is used as an incidence surface, and the other mirror surface is used as a reflection surface, so that the imaging light and the central bright point light formed by the diffractive optical element in the step one are incident into the eliminating prism from the incidence surface and are emitted from the reflection surface;
and secondly, adjusting and eliminating the placing angle of the prism according to the included angle between the imaging light and the central bright spot light, so that the incident angle between the central bright spot light and the reflecting surface reaches a total reflection angle, and the incident angle between the imaging light and the reflecting surface is smaller than total reflection.
As an improved specific implementation manner, the step of arranging the mirror further includes:
and step two, arranging an adjusting prism behind the reflecting surface, wherein the adjusting prism is the same as the eliminating prism, the reflecting surface corresponding to the eliminating prism of the adjusting prism is used as an incident surface, the incident surface corresponding to the eliminating prism of the adjusting prism is used as an emergent surface, imaging light rays are emitted from the emergent surface after being incident from the incident surface and subjected to deviation rectification adjustment, and the emergent imaging light rays are changed in angle due to refraction and are related to the incident angle, so that the image is not only deflected but also elongated and deformed. Through the arrangement of the steps, the same prism can be inversely placed behind the prism to compensate the light path, so that the emergent light angle is the same as the incident light angle, the image cannot be elongated and deformed, and the problem is effectively solved.
In summary, in the method of the present embodiment, the total reflection effect of the generated central bright point light can be effectively achieved through the arrangement of the first step to the second step, so that compared with the manner in the prior art, the central bright point light can be completely eliminated.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
Claims (3)
1. A method for eliminating central bright spot or zero-order diffraction of a diffractive optical element by total reflection is characterized in that: the method comprises the following steps:
step one, arranging a laser light source, a collimating mirror and a diffraction optical element, so that light of the laser light source forms a light beam after passing through the collimating mirror and is emitted into the diffraction optical element, and imaging light rays and central bright spot light rays are formed through the diffraction optical element;
and secondly, arranging a mirror surface behind the diffraction optical element, so that the incident angle between the central bright spot light and the mirror surface is a total reflection angle.
2. The method for eliminating central bright spot or zero order diffraction of a diffractive optical element with total reflection according to claim 1, characterized in that: the mirror surface in the second step is a prism elimination, and the concrete mirror surface setting steps are as follows:
step two, one mirror surface of the eliminating prism is used as an incidence surface, and the other mirror surface is used as a reflection surface, so that the imaging light and the central bright point light formed by the diffractive optical element in the step one are incident into the eliminating prism from the incidence surface and are emitted from the reflection surface;
and secondly, adjusting and eliminating the placing angle of the prism according to the included angle between the imaging light and the central bright spot light, so that the incident angle between the central bright spot light and the reflecting surface reaches a total reflection angle, and the incident angle between the imaging light and the reflecting surface is smaller than the total reflection angle.
3. The method for eliminating central bright spot or zero order diffraction of a diffractive optical element with total reflection according to claim 2, characterized in that: the setting step of the mirror surface further includes:
and step two, arranging an adjusting prism behind the reflecting surface, wherein the adjusting prism is the same as the eliminating prism, the reflecting surface of the adjusting prism corresponding to the eliminating prism is used as an incident surface, and the incident surface of the adjusting prism corresponding to the eliminating prism is used as an emergent surface, so that the imaging light enters from the incident surface, is subjected to deviation rectification adjustment, and then is emitted from the emergent surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110497431.3A CN113189784A (en) | 2021-05-07 | 2021-05-07 | Method for eliminating central bright spot or zero-order diffraction of diffraction optical element by total reflection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202110497431.3A CN113189784A (en) | 2021-05-07 | 2021-05-07 | Method for eliminating central bright spot or zero-order diffraction of diffraction optical element by total reflection |
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| CN113189784A true CN113189784A (en) | 2021-07-30 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107490930A (en) * | 2017-09-01 | 2017-12-19 | 深圳奥比中光科技有限公司 | With the laser projection device for suppressing Zero-order diffractive |
| CN108181294A (en) * | 2018-01-05 | 2018-06-19 | 厦门大学 | Raman spectrometer light path system |
| CN108594452A (en) * | 2018-03-14 | 2018-09-28 | 高世雄 | A method of eliminating diffraction optical element central bright spot |
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2021
- 2021-05-07 CN CN202110497431.3A patent/CN113189784A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107490930A (en) * | 2017-09-01 | 2017-12-19 | 深圳奥比中光科技有限公司 | With the laser projection device for suppressing Zero-order diffractive |
| CN108181294A (en) * | 2018-01-05 | 2018-06-19 | 厦门大学 | Raman spectrometer light path system |
| CN108594452A (en) * | 2018-03-14 | 2018-09-28 | 高世雄 | A method of eliminating diffraction optical element central bright spot |
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Application publication date: 20210730 |
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