CN210666225U - Optical imaging system of transmission type diffraction optical element - Google Patents
Optical imaging system of transmission type diffraction optical element Download PDFInfo
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- CN210666225U CN210666225U CN201921591582.XU CN201921591582U CN210666225U CN 210666225 U CN210666225 U CN 210666225U CN 201921591582 U CN201921591582 U CN 201921591582U CN 210666225 U CN210666225 U CN 210666225U
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Abstract
The utility model discloses a transmission-type diffraction optical element's optical imaging system belongs to the light field regulation and control field, include: a light source and a transmissive diffractive optical element; the light source and the diffraction optical element are arranged on the same optical axis, and the transmission type diffraction optical element is positioned in the direction of emergent light of the light source; the light source is used for providing incident light; the composite phase information is used for adjusting the height and the width of the transmission type diffraction optical surface relief structure so as to obtain a target light field focused at a position different from the optical axis by zero-order light; wherein the composite phase information comprises modulation phase information and focusing phase information; modulating the phase information to generate a target light field after the incident light passes through the transmissive diffractive optical element; the focus phase information is used to focus the target light field and the zero order light at different positions on the optical axis. The utility model discloses a focus phase place makes target light field and zero order light focus in the different positions of optical axis, even there is zero order light not to influence the imaging effect in target light field yet.
Description
Technical Field
The utility model belongs to light field regulation and control field, more specifically relates to a transmission-type diffraction optical element's optical imaging system.
Background
Laser processing is a non-contact processing mode, and has the advantages of high energy density, good directivity, high coherence, small heat affected zone and the like, however, laser beam energy is generally in Gaussian distribution, and in the technical fields such as laser welding, biomedical engineering and the like, the characteristic of non-uniform energy distribution can cause heat accumulation of materials in a local range, thereby damaging the material characteristics and influencing the consistency of processing effects. Through modulating the laser light field, generate special light field distribution, obtain the surface facula of arbitrary special distribution, if: the circular uniform light spot, the rectangular uniform light spot and the annular uniform light spot can meet more laser processing application requirements.
The diffractive optical element has excellent optical performance, can perform phase modulation on incident light to modulate an ideal wave surface, has great advantage in the aspect of correcting chromatic aberration compared with a spherical optical system and an aspheric optical system, can perform beam shaping on the incident light by utilizing the diffractive optical element to generate multiple focuses, and is widely applied to the aspects of laser imaging, laser multi-point processing, laser parallel processing and the like. However, due to the non-continuity of the surface profile of the diffractive optical element, the special phase discontinuity point and the different step heights of the diffractive optical element enable zero-order light to be generated when the diffractive optical element is irradiated by laser, and the final light beam imaging and processing effects are influenced.
The existing method for eliminating zero-order light includes introducing a light beam blocking block, adding Fresnel lens phase and adding cylindrical lens for scattering. The beam blocking block is added in the process of transmitting the zero-order diffraction light to prevent the zero-order diffraction light from continuously transmitting, so that the zero-order diffraction light does not enter the objective lens and does not participate in fluorescence excitation, but the method can introduce a dead zone in an excitation field. The Fresnel lens phase is added when the phase is loaded, a negative lens phase is added, and then a focusing lens is placed on an optical path to separate a zero-order light field from a target light field in the axial direction. The addition of cylindrical lens scattering is to intentionally introduce cylindrical lens aberration in the light path to disperse the zero-order diffraction light, so that the zero-order diffraction light is distributed in a large-range volume, and the light intensity of the zero-order diffraction light in a unit area on a focal plane is reduced, but the method cannot completely eliminate the zero-order light.
SUMMERY OF THE UTILITY MODEL
To prior art's defect, the utility model aims to provide a transmission diffraction optics's optical imaging system aims at solving current light field regulation and control component and leads the relatively poor problem of formation of image result because of having zero order light.
To achieve the above object, the present invention provides an optical imaging system of a transmissive diffractive optical element, including: a light source and a transmissive diffractive optical element;
the light source and the diffraction optical element are arranged on the same optical axis, and the transmission type diffraction optical element is positioned in the direction of emergent light of the light source;
the light source is used for providing incident light for the transmission type diffraction optical element;
the transmission type diffraction optical element is a relief structure, and incident light is subjected to phase modulation based on the relief structure, so that a target light field formed by the transmission type diffraction optical element and zero-pole light form images at different positions on an optical axis.
The dimensions of the relief structure of the transmissive diffractive optical element are determined by the composite phase information; wherein the composite phase information comprises modulation phase information and focusing phase information;
the modulation phase information is used for enabling incident light to generate a target light field after passing through the transmission type diffraction optical element, and the modulation phase information does not contain phase information for enabling the incident light to be focused;
and the focusing phase information is used for adjusting the focusing position of the target light field on the optical axis, so that the target light field and the zero-order light are focused at different positions on the optical axis.
Preferably, the light source is a laser, and the energy of the incident light is gaussian distributed.
Preferably, the optical system of the transmissive diffractive optical element further includes: and the optical imaging processing module is positioned on one side of the transmission type diffraction optical element, which outputs the target light field, and the two sides are positioned on the same optical axis and used for adjusting the image of the near field of the transmission type diffraction optical element or preventing the transmission type diffraction optical element from being damaged.
Preferably, the optical imaging processing module is a single lens or two lenses, and is used for adjusting the imaging position and the imaging size of the image of the near field of the transmission type diffraction optical element.
Preferably, the optical imaging processing module is a protective lens; for protecting the near-field image of the transmissive diffractive optical element.
Preferably, the optical imaging processing module is a combination of a single lens and a protective lens or a combination of two lenses and a protective lens.
Preferably, the distribution of the target light field is a circular uniform spot or a rectangular uniform spot or an annular uniform spot or a planar multi-point distribution.
Through the utility model discloses above technical scheme who thinks, compare with prior art, can gain following beneficial effect:
(1) the utility model provides a surface structure of transmission-type diffraction optical element sets up according to compound phase information for carry out the phase modulation to incident light in order to obtain the target light field with zero level light focus in the different positions of optical axis; wherein the composite phase information comprises modulation phase information and focusing phase information; the modulation phase information is used to generate a target light field after the incident light passes through the transmissive diffractive optical element, and the focusing phase information is used to focus the target light field and the zero-order light at different positions on the optical axis. Compared with the traditional diffractive optical element, the imaging effect of the target light field is influenced by the zero-order light due to the discontinuity of the surface structure, therefore, based on the reason, the target light field and the zero-order light are focused at different positions of the optical axis by adopting the focusing phase, and the imaging effect of the target light field is not influenced even if the zero-order light exists.
(2) The light source can be the laser instrument, and the light beam energy distribution of general laser instrument is the gaussian distribution, in order to keep the uniformity of laser beam machining effect, generally need convert the light field of gaussian distribution into required surperficial facula, and the practical application demand is great, and the utility model discloses a light source can be for the laser instrument, is applicable to laser beam machining equally, fully explains the utility model discloses an application scope is than wide.
(3) The utility model discloses use transmission-type diffraction optical element not to restrict the light source in-service use, need not introduce extra optical element and go the modulation light source, reduced the requirement to hardware for optical system simple structure, easily flexibility operation.
(4) When the utility model discloses a surface structure of transmission-type diffraction optical element is fixed, phase modulation to the incident light has been confirmed, no longer receives the influence of optical path in the optical system, consequently, in practical application, but transmission-type diffraction optical element batch production manufacturing.
(5) The utility model provides an optical system still includes optics formation of image processing module, the formation of image position and the formation of image size of the image of adjustable transmission type diffraction optical element near field to be applicable to various demands.
(6) The utility model discloses only need consider modulation phase information and focus phase information and can avoid the influence of zero order light to the imaging effect of target light field when transmission-type diffraction optical element designs, do not introduce extra optical device, compare the tradition for eliminating zero order light and introduce the light beam barrier block, add fresnel lens phase place and add the post lens scattering, the utility model discloses an optical system is simpler, and is convenient for regulate and control.
Drawings
Fig. 1 is a schematic view of an optical system structure of a transmissive diffractive optical element provided in embodiment 1;
fig. 2 is a flowchart of an optical system operation of the transmissive diffractive optical element provided in embodiment 1;
fig. 3 is a surface structure view of a transmissive diffractive optical element provided in embodiment 1;
fig. 4 is a schematic view of an optical system structure of a transmissive diffractive optical element provided in embodiment 2;
fig. 5 is a schematic view of an optical system structure of a transmissive diffractive optical element provided in embodiment 3;
the same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein: 1-a laser; 2-a diffractive optical element; 3-a single lens; 4-a first lens; 5-a second lens; 6-a workbench.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Because the surface profile of the traditional transmission type diffraction optical element is similar to that of a step and has discontinuity, when incident light passes through a discontinuity point between two steps, phase jump can occur, the phase jump is uncontrollable, and a tiny error is generated during manufacturing, so that zero-order light can be generated when the incident light penetrates through the transmission type diffraction optical element, the imaging effect on a target surface is further influenced, but the zero-order light is not influenced by phase modulation of the transmission type diffraction optical element.
The distribution of the light field on the focusing position and the focusing surface of the target light field generated by the incident light penetrating through the transmission type diffraction optical element is influenced by the height and the width of the step on the surface of the diffraction optical element, and the modulation phase information depends on the height and the width of the step.
The focus position of the target light field generated by the incident light passing through the transmission type diffraction optical element on the optical axis is separated from the focus position of the zero-order light, and finally the target surface is not interfered by the zero-order light.
Based on the above principle, the utility model provides an optical system of transmission-type diffraction optical element, include: a light source and a transmissive diffractive optical element;
the light source and the diffraction optical element are arranged on the same optical axis, and the transmission type diffraction optical element is positioned in the direction of emergent light of the light source;
the light source is used for providing incident light for the transmission type diffraction optical element;
the transmission type diffraction optical element is a relief structure, and incident light is subjected to phase modulation based on the relief structure, so that a target light field formed by the transmission type diffraction optical element and zero-pole light form images at different positions on an optical axis.
The dimensions of the relief structure of the transmissive diffractive optical element are determined by the composite phase information;
wherein the composite phase information comprises modulation phase information and focusing phase information;
the modulation phase information is used for enabling incident light to generate a target light field after passing through the transmission type diffraction optical element, and the modulation phase information does not contain phase information for enabling the incident light to be focused;
and the focusing phase information is used for adjusting the focusing position of the target light field on the optical axis, so that the target light field and the zero-order light are focused at different positions on the optical axis.
Preferably, the optical system of the transmissive diffractive optical element further includes: and the optical imaging processing module is positioned on one side of the transmission type diffraction optical element, which outputs the target light field, and the two sides are positioned on the same optical axis and used for adjusting the image of the near field of the transmission type diffraction optical element or preventing the transmission type diffraction optical element from being damaged.
Preferably, the optical imaging processing module is a single lens or two lenses, and is used for adjusting the imaging position and the imaging size of the image of the near field of the transmission type diffraction optical element.
Preferably, the optical imaging processing module is a protective lens; for protecting the near-field image of the transmissive diffractive optical element.
Preferably, the optical imaging processing module is a combination of a single lens and a protective lens or a combination of two lenses and a protective lens.
Preferably, the distribution of the target light field is a circular uniform spot or a rectangular uniform spot or an annular uniform spot or a planar multi-point distribution.
Example 1
As shown in fig. 1, the present embodiment provides an optical system of a transmissive diffractive optical element, including a laser 1, a transmissive diffractive optical element 2, an einzel lens 3, and a stage 6;
the single lens 3 is an optical imaging processing module; laser light generated by the laser 1 enters the transmission type diffraction optical element 2 to generate a multi-point focused near-field image distributed as required, and the single lens 3 transmits the near-field image of the transmission type diffraction optical element 2 to a final imaging position on the workbench 6.
As shown in fig. 2, based on the optical system of the transmissive diffractive optical element provided above, the present embodiment provides a workflow, which is specifically as follows:
d1: establishing a target light field model according to actual processing requirements, simulating light field transmission by utilizing matlab software according to a diffraction theory and an angular spectrum transmission theory and fast Fourier transform, repeatedly iterating between an input surface and an output surface by adopting a G-S optimization algorithm, and calculating modulation phase information which can change incident Gaussian light into a target light field, wherein the modulation phase information does not contain focusing information of the incident light;
d2: superposing preset focusing phase information and modulation phase information to obtain composite phase information;
d3: setting the surface structure of the transmissive diffractive optical element 2 according to the composite phase information;
as shown in fig. 3, the surface structure of the transmissive optical element 2 in this embodiment is a relief structure, and the relief structure is loaded with composite phase information;
d4: the transmission type diffraction optical element 2 performs phase modulation on incident laser, converts the incident laser with light intensity distribution of Gaussian distribution into a plurality of beams of focused light meeting the processing requirement, and the beams of focused light are distributed according to a target light field;
the generated target light field and zero-order light are focused at different positions of an optical axis, and the focus surface of the target light field has no interference of the zero-order light;
d5: transmitting an image formed by the near field modulated by the transmission type diffraction optical element 2 to a position on a workbench 6 to be imaged finally by using the single lens 3;
the final imaging size and position can be realized by adjusting the relationship between the position and the focal length of the single lens 3 according to the size and the focusing position of the near-field image, but the final imaging effect is not influenced.
According to the imaging principle, the object image relationship of the optical system satisfies:
wherein f is3Is the focal length of the single lens 3; l1The distance from the focal plane of the transmission type diffraction optical element to the single lens 3; l2The distance from the einzel lens 3 to the stage 6.
Example 2
As shown in fig. 4, the present embodiment provides an optical system of a transmissive diffractive optical element, including: a laser 1, a transmissive diffractive optical element 2, a first lens 4, a second lens 5, and a stage 6;
the first lens 4 and the second lens 5 form an optical imaging processing module; laser generated by the laser 1 is incident on the transmission type diffraction optical element 2 to generate a multi-point focused near-field image distributed as required, and an optical imaging processing module composed of a first lens 4 and a second lens 5 transmits the near-field image of the transmission type diffraction optical element 2 to a position on a workbench 6 to be imaged finally.
The working flow of the optical system of the transmissive diffractive optical element provided in embodiment 2 is similar to that provided in embodiment 1, and the only difference is that a single lens 3 is adopted as the optical imaging processing module in embodiment 1, a first lens 4 and a second lens 5 are adopted as the optical imaging processing module in embodiment 2, and D5 of embodiment 2 is: an image formed by the approach field modulated by the transmission type diffraction optical element 2 is transmitted to a position on a workbench 6 to be imaged finally by using a first lens 4 and a second lens 5; the final imaging size and position can be realized by adjusting the relationship between the positions and focal lengths of the first lens 4 and the second lens 5 according to the size and focusing position of the near-field image, and the final imaging effect is not affected.
Example 3:
as shown in fig. 5, the present embodiment provides an optical system of a transmissive diffractive optical element, including: a laser 1, a transmission type diffraction optical element 2, a protective glass and a workbench 6;
the protective mirror has a protective effect on the transmission type diffraction optical element and has no influence on a light path and imaging; laser light generated by the laser 1 is incident on the transmissive diffractive optical element 2, and finally, a multi-point focused near-field image distributed as desired is generated on the stage 6.
The utility model provides an optics formation of image processing module is not restricted to single lens or two lenses or protective glass and the combination of one of them, and the image of adjustable transmission type diffraction optical element near field or the image position and the optical element of formation of image size of adjusting the image of transmission type diffraction optical element near field are all suitable for.
In actual use, the laser meeting the parameter requirements of power, wavelength, frequency and the like is selected according to the use requirement.
The utility model discloses the light source is not restricted to the laser instrument, and the incident beam of production is not restricted to laser beam, and light distribution also is not restricted to gaussian distribution's incident beam.
Although the present specification uses terms such as the laser 1, the diffractive optical element 2, the single lens 3, the first lens 4, the second lens 5, the stage 6, and the protective mirror more, the possibility of using other terms is not excluded. These terms are used merely to more conveniently describe the nature of the invention and should not be construed as imposing any additional limitations thereon which would depart from the spirit of the invention.
To sum up, the utility model provides a surface structure of transmission-type diffractive optical element sets up according to compound phase information for carry out the phase modulation to incident light in order to obtain with the target light field of zero order light focus in the different positions of optical axis; wherein the composite phase information comprises modulation phase information and focusing phase information; the modulation phase information is used to generate a target light field after the incident light passes through the transmissive diffractive optical element, and the focusing phase information is used to focus the target light field and the zero-order light at different positions on the optical axis. Compared with the traditional diffractive optical element, the imaging effect of the target light field is influenced by the zero-order light due to the discontinuity of the surface structure, therefore, based on the reason, the target light field and the zero-order light are focused at different positions of the optical axis by adopting the focusing phase, and the imaging effect of the target light field is not influenced even if the zero-order light exists.
The utility model discloses only need consider modulation phase information and focus phase information and can avoid the influence of zero order light to the imaging effect of target light field when transmission-type diffraction optical element designs, do not introduce extra optical device, compare the tradition for eliminating zero order light and introduce the light beam barrier block, add fresnel lens phase place and add the post lens scattering, the utility model discloses an optical system is simpler, and is convenient for regulate and control.
The utility model discloses use transmission-type diffraction optical element not to restrict the light source in-service use, need not introduce extra optical element and go the modulation light source, reduced the requirement to hardware for optical system simple structure, easily flexibility operation.
When the utility model discloses a surface structure of transmission-type diffraction optical element is fixed, phase modulation to the incident light has been confirmed, no longer receives the influence of optical path in the optical system, consequently, in practical application, but transmission-type diffraction optical element batch production manufacturing.
It will be understood by those skilled in the art that the foregoing is merely a preferred embodiment of the present invention, and is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Claims (8)
1. An optical imaging system of a transmissive diffractive optical element, comprising: a light source (1), a transmissive diffractive optical element (2);
the light source (1) is used for providing incident light for the transmission type diffraction optical element (2);
the transmission type diffraction optical element (2) is a relief structure, and incident light is subjected to phase modulation based on the relief structure, so that a target light field formed by the transmission type diffraction optical element (2) and zero-pole light are imaged at different positions on an optical axis.
2. The optical imaging system according to claim 1, characterized in that the dimensions of the relief structure of the transmissive diffractive optical element (2) are determined by composite phase information;
wherein the composite phase information comprises modulation phase information and focus phase information;
the modulation phase information is used for generating a target light field after the incident light passes through the transmission type diffraction optical element (2);
the focusing phase information is used for determining the focusing position of the target light field on the optical axis, so that the target light field and the zero-order light are focused at different positions on the optical axis.
3. Optical imaging system according to claim 1, characterized in that the light source (1) is a laser and the energy of the incident light is gaussian distributed.
4. The optical imaging system according to claim 1, further comprising an optical imaging processing module, located on the side of the transmissive diffractive optical element (2) from which the target light field is output, and both located on the same optical axis, for adjusting the image of the transmissive diffractive optical element (2) near field or preventing damage of the transmissive diffractive optical element (2).
5. The optical imaging system according to claim 4, characterized in that the optical imaging processing module is a single lens (3) or two lenses for adjusting the imaging position and the imaging size of the image of the near field of the transmissive diffractive optical element (2).
6. The optical imaging system of claim 4, wherein the optical imaging processing module is a protective glass; for preventing damage to the transmissive diffractive optical element (2).
7. The optical imaging system according to claim 4, characterized in that the optical imaging processing module is a combination of a single lens (3) and a protective lens or a combination of two lenses and a protective lens.
8. The optical imaging system of claim 1, wherein the distribution of the target light field is a circular uniform spot or a rectangular uniform spot or an annular uniform spot or a planar multi-point distribution.
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| CN110554510A (en) * | 2019-09-23 | 2019-12-10 | 华中科技大学 | Optical imaging system of transmission type diffraction optical element |
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| CN110554510A (en) * | 2019-09-23 | 2019-12-10 | 华中科技大学 | Optical imaging system of transmission type diffraction optical element |
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