A zero-order wave plate and optical component with equal-thickness double-plate combination
By adopting a single -axis dual -refractive crystal sheet with equal thickness in the double -chip combination zero -level wave film, and through the optical polishing surface design, the phase delay bias caused by the thickness errors, the higher phase delay accuracy is achieved.
Patent Information
- Application Number
- CN202211058640.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-08-30
- Publication Date
- 2025-01-28
- Estimated Expiration
- 2042-08-30
AI Technical Summary
The problem of phase delay amount deviation caused by thickness error of the existing double-chip combination zero-order wave plate affects the accuracy of the phase delay amount.
Two -piece zero -level waves with equal thickness, two of which are single -axis dual refractive crystals, which are consistent with the thickness, and control the thickness error through the optical polishing surface design.
The impact of the accuracy error of the optical axis angle on the combination phase delay is reduced. The control phase delay deviation deviation is within 1 °, which is only one -third of the conventional dual combination.
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Figure CN115343793B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of polarization optical applications, and in particular to a zero-order wave plate and an optical component combined with two equal-thickness plates. Background Art
[0002] In modern polarization optical application technology, phase retarders are usually used to change the polarization properties of light. Phase retarders are of two types: rhombus-shaped ones made of isotropic materials and sheets made of uniaxial birefringent crystals. The former is called an achromatic phase retarder, which can be used in a wider spectral range, but it is not easy to make a larger aperture, and it is bulky, extremely inconvenient to install and debug, so it is rarely used; the latter can be made into a large sheet aperture according to the scale of the material, usually called a wave plate. Wave plates generally include: single-piece wave plates, multi-stage plates, and double-piece combined zero-order wave plates (also called conventional combined zero-order wave plates). Among them, single-piece wave plates mainly use muscovite, quartz crystals, and magnesium fluoride crystals with low birefringence. However, the optical plane and mechanical strength of muscovite wave plates are poor, and the processing difficulty of quartz crystal and magnesium fluoride crystal zero-order wave plates is relatively large. The mechanical strength of multi-stage plates is better than that of single-piece wave plates, but the delay of multi-stage plates is greatly affected by the ambient temperature of use, which is not conducive to use in natural environments. Therefore, the double-plate combination zero-order wave plate is favored by users due to its good mechanical strength and measurement accuracy that is less affected by temperature.
[0003] At present, the thickness error of the double-plate combined zero-order wave plate can be controlled within 0.5μm. However, through calculation, for the conventional combined zero-order 650nm wave plate made of quartz crystal, a deviation of 0.5μm thickness difference can produce a phase delay deviation of 2.5°, affecting the phase delay accuracy of the double-plate combined zero-order wave plate. Summary of the invention
[0004] In order to solve at least one technical problem in the prior art, an embodiment of the present invention provides a zero-order wave plate and an optical component composed of two equal-thickness plates. The technical solution is as follows:
[0005] In a first aspect, a zero-order wave plate composed of two equal-thickness plates is provided, comprising:
[0006] A first crystal plate, comprising: an incident end face of a zero-order wave plate, wherein the crystal optical axis of the first crystal plate is within the incident face of the zero-order wave plate;
[0007] The second crystal plate comprises: an exit surface of the zero-order wave plate, wherein the optical axis of the second crystal plate is arranged at an angle to a normal line of the incident surface of the zero-order wave plate;
[0008] The first crystal plate is connected to the second crystal plate, both the first crystal plate and the second crystal plate are uniaxial birefringent crystals, the first crystal plate and the second crystal plate have the same thickness, and the incident surface of the zero-order wave plate is parallel to the exit surface of the zero-order wave plate.
[0009] Furthermore, the incident surface of the first crystal sheet and the exit surface of the first crystal sheet are both optically polished surfaces, and the incident surface of the second crystal sheet and the exit surface of the second crystal sheet are both optically polished surfaces.
[0010] Furthermore, the first crystal sheet and the second crystal sheet are glued together.
[0011] Furthermore, the first crystal piece and the second crystal piece have the same shape.
[0012] Furthermore, the second crystal plate and the first crystal plate are uniaxial birefringent crystals made of the same material, and the uniaxial birefringent crystals include: any one of magnesium fluoride crystals, optical quartz crystals, sapphire crystals, lithium niobate crystals, Iceland spar crystals, α-BBO crystals, yttrium vanadate crystals, and rutile crystals.
[0013] Furthermore, when the incident light enters from the incident surface of the zero-order wave plate, the optical axis angle of the outgoing light emitted from the outgoing surface of the zero-order wave plate satisfies:
[0014]
[0015] in, is the optical axis angle of the outgoing light, d is the thickness of the first crystal sheet and the second crystal sheet, λ is the wavelength of the outgoing light, ± indicates that the sign is - when a positive uniaxial birefringent crystal is used, and the sign is + when a negative uniaxial birefringent crystal is used, n e 、n o It is the principal refractive index of the e and o light waves in the uniaxial birefringent crystal used. When n is 1, 2, 3 and 4, it corresponds to λ / 4, λ / 2, 3λ / 4 and full-wave plate respectively.
[0016] Furthermore, at the optical axis angle of the emitted light When a certain value is met, the thickness of the first crystal sheet and the second crystal sheet satisfies:
[0017]
[0018] Wherein, d is the thickness of the first crystal sheet and the second crystal sheet, is the optical axis angle of the outgoing light, ± indicates that when a positive uniaxial birefringent crystal is used, a - sign is taken, and when a negative uniaxial birefringent crystal is used, a + sign is taken, n e 、n oIt is the principal refractive index of the e and o light waves in the uniaxial birefringent crystal used. Its value is a function of the wavelength λ. When n is 1, 2, 3 and 4, it corresponds to λ / 4, λ / 2, 3λ / 4 and full-wave plate respectively.
[0019] In a second aspect, an optical component is provided, comprising a zero-order wave plate of equal-thickness double-plate combination as described in any one of the first aspects.
[0020] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:
[0021] 1. The equal-thickness double-plate combined zero-order wave plate proposed in the present invention comprises two uniaxial birefringent crystal plates of the same thickness, and there is no thickness difference between the two crystal plates, thereby reducing the influence of the precision error of the optical axis angle on the combined phase delay.
[0022] 2. The incident surface and the exit surface of the first crystal plate and the second crystal plate in the zero-order wave plate of equal thickness double-plate combination proposed by the present invention are both polished surfaces, so that the processing error of the crystal plate thickness can be controlled, and the influence of the crystal plate thickness processing error on the phase delay amount is reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0024] Figure 1 It is a structural diagram of a zero-order wave plate composed of two equal-thickness plates disclosed in an embodiment of the present invention;
[0025] Figure 2 It is a cross-sectional view of the second crystal plate of the zero-order wave plate of the double-plate combination of equal thickness disclosed in an embodiment of the present invention. DETAILED DESCRIPTION
[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0027] It should be noted that the expressions “first” and “second” used in the embodiments of the present invention are intended to distinguish two non-identical entities with the same name or non-identical parameters. It can be seen that “first” and “second” are only for the convenience of expression and should not be understood as limitations on the embodiments of the invention. The subsequent embodiments will not explain this one by one.
[0028] like Figure 1 As shown, a zero-order wave plate composed of two equal-thickness plates comprises: a first crystal plate 1 and a second crystal plate 2. The first crystal plate 1 and the second crystal plate 2 have the same thickness and are arranged in parallel. The first crystal plate 1 and the second crystal plate 2 both comprise an incident surface and an exit surface, wherein the incident surface of the first crystal plate 1 is the incident surface of the zero-order wave plate, the exit surface of the second crystal plate 2 is the exit surface of the zero-order wave plate, and the exit surface of the first crystal plate 1 is connected to the incident surface of the second crystal plate 2.
[0029] It should be noted that: the first crystal plate 1 and the second crystal plate 2 have the same thickness, so there is no difference in thickness between the two crystal plates, but during the processing, due to the problem of mechanical processing accuracy, the thickness of the two crystal plates will have the same processing error. Experimental calculations show that the processing error of 0.5μm has an effect of less than 0.1° on the combined phase delay of the wave plate disclosed in the present invention, which is only about 4% of the conventional double-plate combination. In actual production, the optical axis angle accuracy can be completely controlled within 0.05° (3′). Calculations show that the accuracy error of the optical axis angle of 0.05° affects the combined phase delay by about 0.8°. It can be seen that the phase delay deviation of the zero-order wave plate of the equal-thickness double-plate combination proposed by the present invention can be controlled within 1°, which is only one-third of the same thickness deviation of the conventional double-plate combination.
[0030] As mentioned above, the incident surface mainly refers to the incident surface of the incident light, and the exit surface mainly refers to the exit surface of the exit light. Therefore, the definitions of the incident surface and the exit surface of the zero-order wave plate are related to the incident position of the incident light and the exit position of the exit light: light can be incident from the first crystal plate 1 and exit from the second crystal plate 2, or it can be incident from the second crystal plate 2 and exit from the first crystal plate 1. If the incident light is incident from the first crystal plate 1, the first crystal plate 1 includes the incident end face of the zero-order wave plate. If the incident light is incident from the second crystal plate 2, the second crystal plate 2 includes the incident end face of the zero-order wave plate. Similarly, if the exit light is exited from the second crystal plate 2, the second crystal plate 2 includes the exit surface of the zero-order wave plate. If the exit light is exited from the first crystal plate 1, the first crystal plate 1 includes the exit surface of the zero-order wave plate. Figure 2 This is a cross-sectional view of the second crystal plate 2 of the zero-order wave plate of the equal-thickness double-plate combination. The double arrow OC in the figure indicates the direction of the crystal optical axis. is the crystal optical axis angle.
[0031] As a case, both the incident surface and the exit surface of the first crystal piece 1 are optically polished surfaces, and both the incident surface and the exit surface of the second crystal piece 2 are optically polished surfaces.
[0032] As mentioned above, the first crystal sheet 1 and the second crystal sheet 2 are optically polished mainly to control the thickness of the first crystal sheet 1 and the second crystal sheet 2 to be consistent.
[0033] As a case, the first crystal sheet 1 and the second crystal sheet 2 are glued and connected, for example, by cross-coated optical glue.
[0034] As a case, the first crystal piece 1 and the second crystal piece 2 have the same shape. As mentioned above, the first crystal piece 1 and the second crystal piece 2 can be sheet structures of any shape, preferably circular or quadrilateral sheet structures.
[0035] As a case, the first crystal piece 1 and the second crystal piece 2 are uniaxial birefringent crystals of the same material, and the uniaxial birefringent crystals include: any one of magnesium fluoride crystal, optical quartz crystal, sapphire crystal, lithium niobate crystal, Iceland spar crystal, α-BBO crystal, yttrium vanadate crystal, rutile crystal, etc.
[0036] As a case, the angle between the crystal optical axis and the end normal of the parallel plate is called the optical axis angle. In the zero-order wave plate of equal thickness double-plate combination, the optical axis angle of the first crystal plate 1 is 90°, and the optical axis angle of the second crystal plate 2 is It means that when the thickness d of the first crystal sheet 1 and the second crystal sheet 2 is given, the optical axis angle of the second crystal sheet 2 Given by:
[0037]
[0038] When the optical axis angle of the second crystal plate 2 Given, the thickness d is given by:
[0039]
[0040] The ± in formula (1) and formula (2) indicates that the sign is - when a positive uniaxial birefringent crystal is used, and the sign is + when a negative uniaxial birefringent crystal is used; n e 、n o It is the principal refractive index of the e and o light waves in the uniaxial birefringent crystal used, and its value is a function of the wavelength λ; when n is 1, 2, 3 and 4, it corresponds to λ / 4, λ / 2, 3λ / 4 and full-wave plate respectively.
[0041] The zero-order wave plate of equal-thickness double-plate combination disclosed in the present invention is specifically described below in conjunction with specific embodiments:
[0042] A positive uniaxial optical quartz crystal is used to design a λ / 4 crystal plate with a thickness of 500μm and a wavelength of 0.65μm, that is, d = 500μm, λ = 0.65μm, n = 1, and n is obtained by the dispersion formula of the quartz crystal. e =1.551113538,n o =1.542084112, Substituting the above data into formula (1) and taking the minus sign, we can obtain: The optical axis angle of the second crystal piece 2
[0043] If the optical axis angle of the second crystal plate 2 is selected Set λ = 0.65 μm, n = 1, n e =1.551113538,n o =1.542084112, substituting into (2) we can also obtain that the thickness of the first crystal sheet and the second crystal sheet both satisfy: d = 500 μm.
[0044] That is, a design parameter of a 0.65μm quarter-order zero-order wave plate composed of two quartz crystals of equal thickness is: thickness d = 500μm, the optical axis angle of the first crystal plate 1 is 90°, and the optical axis angle of the second crystal plate 2 is
[0045] Example 2
[0046] The similarities between this embodiment and embodiment 1 are not repeated here. The difference is that a λ / 2 crystal sheet with λ=0.65μm is designed, that is, n=2, and the thickness of the first crystal sheet 1 and the second crystal sheet 2 is 600μm. e =1.551113538,n o =1.542084112, substituting into (1) and taking the minus sign, we get: the optical axis angle of the second crystal piece 2
[0047] A design parameter of a 0.65μm half-order wave plate composed of two quartz crystals of equal thickness is as follows: thickness d = 600μm, the optical axis angle of the first crystal piece 1 is 90°, and the optical axis angle of the second crystal piece 2 is
[0048] Example 3
[0049] The similarities between this embodiment and embodiment 1 are not repeated here. The difference is that the design wavelength λ is 0.532 μm, and n is obtained by the dispersion formula of the quartz crystal. e =1.556093433, n o=1.546896209, and substituting it with d=500μm, λ=0.532μm, and n=1 into formula (1) and replacing the sign of ±, we can obtain:
[0050] A design parameter of a 0.532μm quarter-order zero-order wave plate composed of two quartz crystals of equal thickness is as follows: thickness d = 500μm, the optical axis angle of the first crystal plate 1 is 90°, and the optical axis angle of the second crystal plate 2 is
[0051] Example 4
[0052] The similarities between this embodiment and embodiment 1 are not repeated here. The difference is that the λ / 2 wave plate with a design wavelength λ=0.532μm, that is, n=2, and the thickness of the parallel flat crystal of the quartz crystal is 600μm. The dispersion formula of the quartz crystal is used to obtain n e =1.556093433, n o =1.546896209, and substituting it with d=600μm, λ=0.532μm, and n=2 into formula (1) and replacing the ± with the - sign, we can obtain:
[0053] A design parameter of a 0.532μm half-order wave plate composed of two quartz crystals of equal thickness is as follows: thickness d = 600μm, the optical axis angle of the first crystal piece 1 is 90°, and the optical axis angle of the second crystal piece 2 is
[0054] Example 5
[0055] The similarities between this embodiment and embodiment 1 are not repeated here. The difference is that the design wavelength λ is 0.85 μm, and n is obtained by the dispersion formula of the quartz crystal. e =1.546268957, n o =1.537418412, and substituting it with d=500μm, λ=0.85μm, and n=1 into formula (1) and taking the minus sign, we can obtain: About 77°40′.
[0056] A design parameter of a 0.85μm quarter-order zero-order wave plate composed of two quartz crystals of equal thickness is as follows: thickness d = 500μm, the optical axis angle of the first crystal plate 1 is 90°, and the optical axis angle of the second crystal plate 2 is
[0057] Example 6
[0058] The similarities between this embodiment and embodiment 1 are not repeated here. The difference is that the λ / 2 wave plate with a wavelength λ=0.85μm is designed, that is, n=2, and the thickness of the first crystal plate 1 and the second crystal plate 2 is 600μm. The dispersion formula of the quartz crystal is used to obtain n e =1.546268957, n o =1.537418412, and substituting it with d=600μm, λ=0.85μm, and n=2 into formula (1) and taking the minus sign, we can obtain:
[0059] A design parameter of a 0.85μm half-order wave plate composed of two quartz crystals of equal thickness is as follows: thickness d = 600μm, the optical axis angle of the first crystal piece 1 is 90°, and the optical axis angle of the second crystal piece 2 is
[0060] Example 7
[0061] The similarities between this embodiment and embodiment 1 are not repeated here. The difference is that a positive uniaxial magnesium fluoride crystal is used and a λ / 4 wave plate with a design wavelength λ=0.532 μm is used. The dispersion formula of the magnesium fluoride crystal is used to obtain n e =1.390780932, n o =1.37892885, and substituting it with d=500μm, λ=0.532μm, and n=1 into formula (1) and taking the minus sign, we can obtain:
[0062] A design parameter of a 0.532μm quarter-order zero-order wave plate composed of two pieces of magnesium fluoride crystal with equal thickness is as follows: thickness d = 500μm, the optical axis angle of the first crystal piece 1 is 90°, and the optical axis angle of the second crystal piece 2 is
[0063] Example 8
[0064] The similarities between this embodiment and embodiment 1 are not described in detail. The difference is that negative uniaxial sapphire (Al2O3) crystal is used, and a λ / 4 wave plate with a design wavelength λ=0.5893μm is used. The main refractive index n of sapphire crystal at 0.5893μm is e =1.7600, n o =1.7685, and substituting it with d=500μm, λ=0.532μm, and n=1 into formula (1) and replacing ± with + sign, we can obtain:
[0065] A design parameter of a 0.5893μm quarter zero-order wave plate composed of two sapphire crystals of equal thickness is as follows: thickness d = 500μm, the optical axis angle of the first crystal plate 1 is 90°, and the optical axis angle of the second crystal plate 2 is
[0066] Example 9
[0067] The similarities between this embodiment and embodiment 1 are not repeated here. The difference is that a negative uniaxial barium borate (α-BBO) crystal is used, and a λ / 4 wave plate with a design wavelength λ=0.808 μm is used. The dispersion formula of the barium borate crystal is used to obtain n e =1.525366184, n o =1.663686153, and substituting it with d=500μm, λ=0.808μm, and n=1 into formula (1) and replacing ± with +, we can obtain:
[0068] That is, a design parameter of a 0.808μm quarter-order wave plate composed of two pieces of equal thickness of barium metaborate crystal is: thickness d = 500μm, the optical axis angle of the first crystal piece 1 is 90°, and the optical axis angle of the second crystal piece 2 is
[0069] Based on the equal-thickness double-plate combination disclosed in the above embodiment of the present invention, the embodiment of the present invention further provides an optical component, including: an equal-thickness double-plate combination zero-order wave plate, wherein the zero-order wave plate includes:
[0070] The first crystal plate 1 comprises: an incident surface of a zero-order wave plate, wherein the crystal optical axis of the first crystal plate 1 is within the incident surface of the zero-order wave plate;
[0071] The second crystal plate 2 comprises: an exit surface of the zero-order wave plate, wherein the crystal optical axis of the second crystal plate 2 is arranged at an angle to the normal of the incident surface of the zero-order wave plate;
[0072] The first crystal plate 1 is connected to the second crystal plate 2. Both the first crystal plate 1 and the second crystal plate 2 are uniaxial birefringent crystals. The first crystal plate 1 and the second crystal plate 2 have the same thickness. The incident surface of the zero-order wave plate is parallel to the exit surface of the zero-order wave plate.
[0073] The technical solution provided by the present application is described in detail above. The principle and implementation method of the present application are described in detail using specific examples. The description of the above embodiments is only used to help understand the method and core idea of the present application. At the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as limiting the present application.
[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A zero-order wave plate composed of two equal-thickness plates, characterized in that: include: A first crystal plate, comprising: an incident end face of a zero-order wave plate, wherein a crystal optical axis of the first crystal plate is within the incident face of the zero-order wave plate and parallel to the incident end face; The second crystal plate comprises: an exit end face of the zero-order wave plate, wherein a crystal optical axis of the second crystal plate and a normal line of an incident face of the zero-order wave plate are arranged at an angle, and the angle is an optical axis angle; The first crystal sheet is connected to the second crystal sheet, the first crystal sheet and the second crystal sheet are both uniaxial birefringent crystals, the first crystal sheet and the second crystal sheet have the same thickness, and the incident surface of the zero-order wave plate is parallel to the exit surface of the zero-order wave plate; When the incident light enters from the incident end face of the zero-order wave plate, the optical axis angle of the second crystal plate satisfies: in, is the optical axis angle of the second crystal sheet, d is the thickness of the first crystal sheet and the second crystal sheet, λ is the wavelength of the emitted light, ± indicates that the sign is - when a positive uniaxial birefringent crystal is used, and the sign is + when a negative uniaxial birefringent crystal is used, n e 、n o is the principal refractive index of the e and o light waves in the uniaxial birefringent crystal used. When n is 1, 2, 3 and 4, it corresponds to λ / 4, λ / 2, 3λ / 4 and full-wave plate respectively; The optical axis angle of the second crystal When the thickness of the first crystal sheet and the second crystal sheet both satisfy:
2. The wave plate according to claim 1, characterized in that The incident end face of the first crystal piece and the exit end face of the first crystal piece are both optically polished surfaces, and the incident end face of the second crystal piece and the exit end face of the second crystal piece are both optically polished surfaces.
3. The wave plate according to claim 1, characterized in that: The first crystal sheet and the second crystal sheet are glued together.
4. The wave plate according to claim 1, wherein: The first crystal piece and the second crystal piece have the same shape.
5. The wave plate according to claim 1, characterized in that: The first crystal sheet and the second crystal sheet are uniaxial birefringent crystals made of the same material, and the uniaxial birefringent crystals include: any one of magnesium fluoride crystal, optical quartz crystal, sapphire crystal, lithium niobate crystal, Iceland spar crystal, α-BBO crystal, yttrium vanadate crystal, and rutile crystal.
6. An optical component, characterized in that: It comprises a zero-order wave plate composed of two plates of equal thickness as described in any one of claims 1 to 5.