Large aperture silicon lens aspheric surface turning method

Abstract

The application discloses a large-aperture silicon lens aspheric surface turning processing method, comprising the following steps: processing the aperture of the aspheric surface of a silicon lens blank to a first value, the first value being greater than the set value of the aperture of the aspheric surface of the silicon lens after turning is completed; selecting a set form of turning line, and calculating the total length of the turning track formed by turning the aperture size of the aspheric surface of the silicon lens from the first value to the set value; using a set turning tool, and turning a test piece with the same material as the silicon lens in a set form to obtain the distance that the blade surface of the set turning tool can keep the set turning accuracy, which is recorded as the accurate turning length; according to the total length and the accurate turning length, obtaining the number information of the tools required to be replaced for completing the turning and the position information of the tools to be replaced; according to the number information and the position information, turning the silicon lens with the aperture of the aspheric surface processed to the first value to obtain the silicon lens with the aspheric surface with the set precision.

Description

TECHNICAL FIELD

[0001] The present application generally relates to the technical field of single-point diamond ultra-precision turning, and particularly relates to a large-aperture silicon lens aspheric surface turning machining method. BACKGROUND

[0002] The silicon lens has been widely used in infrared detectors or infrared imagers due to its good transmittance to infrared light. At present, for the machining of small-aperture or general-aperture silicon lenses, a classical machining method is generally adopted, that is, a lower-precision tool is first used to pre-polish the fitting spherical surface on the lens blank to a certain extent, and then a higher-precision tool is used to precisely turn the pre-polished blank, so that the fitting spherical surface of the silicon lens reaches the set precision. However, the higher-precision tool has a certain machining life, and after turning a set length, the blade surface will be worn to cause the machining precision to not meet the requirements. The existing scheme can achieve good effects in the turning of relatively small machining amount of silicon lenses. However, when facing the machining task of large-aperture silicon lenses with large machining amount, it is easy to cause the machining precision of the silicon lens to not meet the requirements due to the excessive use of the tool blade surface and wear. Therefore, how to ensure the machining precision of the large-aperture silicon lens has become a problem to be solved in the field. SUMMARY

[0003] In view of the above defects or deficiencies in the prior art, it is desirable to provide a turning method capable of improving the machining precision of the aspheric surface of a large-aperture silicon lens.

[0004] The specific technical scheme comprises the following steps:

[0005] The aperture of the aspheric surface on the silicon lens blank is machined to a first value, which is greater than the set value of the aperture of the aspheric surface on the silicon lens after turning is completed;

[0006] A turning route of a set form is selected, and the total length of the turning track formed by turning the aperture size of the aspheric surface on the silicon lens from the first value to the set value is calculated;

[0007] A set turning tool is used, and a test piece made of the same material as the silicon lens is turned in the set form to obtain the distance that the blade surface of the set turning tool can maintain the set turning precision, which is recorded as the accurate turning length;

[0008] According to the total length and the accurate turning length, the number information of the tools to be replaced for completing the turning and the position information of the tools to be replaced are obtained;

[0009] According to the number information and the position information, the silicon lens whose aspheric surface aperture is machined to the first value is turned to obtain a silicon lens with an aspheric surface having a set precision.

[0010] As a further limitation of the present application, the selecting the turning route in the set form specifically comprises the following steps:

[0011] selecting a polar coordinate origin and a turning starting point on the silicon lens aspherical surface processed to the first numerical value;

[0012] turning according to a typical Archimedes spiral trajectory, and the spiral trajectory equation is r=a+bθ, where a and b are real numbers, a is the distance between the polar coordinate origin and the turning starting point, and b is the distance between adjacent spirals.

[0013] As a further limitation of the present application, the turning test on the test piece of the same material as the silicon lens in the set form to obtain the distance at which the set turning tool blade can maintain the set turning accuracy specifically comprises the following steps:

[0014] turning the test piece from the center to the edge according to a typical Archimedes spiral trajectory;

[0015] observing the test piece during turning to obtain a mutation point of the turning accuracy of the surface of the test piece;

[0016] obtaining the distance between the turning starting point and the mutation point.

[0017] As a further limitation of the present application, the obtaining the distance between the turning starting point and the mutation point specifically comprises the following steps:

[0018] According to the following formula, the polar coordinates of the mutation point are converted into Cartesian coordinates,

[0019] x=r·cos(θ)

[0020] y=r·sin(θ)

[0021] where r and θ are the polar coordinates of the mutation point, and x and y are the corresponding Cartesian coordinates;

[0022] According to the following formula, the number of turns of the mutation point in the trajectory of the Archimedes spiral from inside to outside is obtained,

[0023] revs o =(o / f) / 2

[0024] where o represents the distance between the mutation point and the polar coordinate origin, and f=2πb represents the spiral pitch;

[0025] According to the following formula, the corresponding angle of the mutation point in the Archimedes spiral is obtained,

[0026] DEGREE o = revs o * 360°

[0027] According to the following formula, the distance between the turning starting point and the mutation point is obtained,

[0028]

[0029] As a further limitation of the present application, the turning test on the test piece of the same material as the silicon lens material in the set form is performed to obtain the distance at which the set turning tool blade surface can maintain the set turning accuracy, and further includes the following steps:

[0030] The above test is performed multiple times, and multiple test values of the distance at which the set turning tool blade surface can maintain the set turning accuracy are obtained respectively;

[0031] The arithmetic mean of the multiple test values is calculated to obtain the distance at which the set turning tool blade surface can maintain the set turning accuracy.

[0032] As a further limitation of the present application, the number information and the position information of the tool to be replaced for completing turning are obtained according to the total length and the accurate turning length, and specifically include the following steps:

[0033] According to the following formula, the number information of the tool to be replaced for completing turning is obtained,

[0034]

[0035] Wherein, L is the total length;

[0036] According to the following formula, the position information of the tool to be replaced is obtained,

[0037]

[0038] D i = 2*f*β i / 360°

[0039] Wherein, D i is the radial position information of the mutation point on the Archimedes spiral line, β i

[0040] is the corresponding angle on the Archimedes spiral line when the turning length is i*L i .

[0041] The application has the beneficial effects that:

[0042] The present scheme can process the aperture of the aspheric surface of the silicon lens from the first value to the set value by presetting the turning form of the silicon lens, obtaining the turning track of the silicon lens, and turning the silicon lens according to the track. In addition, by turning the test piece with the same material as the silicon lens, the maximum length that can be turned by the set turning tool under the premise of ensuring the turning precision, that is, the accurate turning length, can be obtained. The position information and the number information of the set turning tool that needs to be replaced during the turning process can be obtained by the ratio of the total length to the accurate turning length. Finally, according to the above position information and number information, the set turning tool is replaced when the silicon lens is processed, so that the set turning tool for processing the silicon lens can always be in a state of not being excessively worn, and the precision of the aspheric surface of the silicon lens processed thereby will also meet the set requirements. The present scheme is not affected by the pre-polishing degree of the silicon lens blank and the specific size of the silicon lens, and can ensure the turning precision of the silicon lens. BRIEF DESCRIPTION OF DRAWINGS

[0043] Other features, objects, and advantages of the application will become more apparent from the following detailed description of non-limiting embodiments, when read in conjunction with the accompanying drawings:

[0044] Figure 1 A step flow chart of a large-aperture silicon lens aspheric surface turning processing method provided by the embodiment of the present application. DETAILED DESCRIPTION

[0045] The present application will be 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 intended to explain the related application, but not to limit the application. In addition, it should be noted that only the parts related to the application are shown in the drawings for ease of description.

[0046] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and embodiments.

[0047] Please refer to Figure 1 A large-aperture silicon lens aspheric surface turning processing method provided by the embodiment includes the following steps:

[0048] S1: processing the aperture of the aspheric surface of the silicon lens blank to a first value, the first value being greater than the set value of the aperture of the aspheric surface of the silicon lens after turning;

[0049] S2: selecting a set form of turning line, and calculating the total length of the turning track formed by turning the aperture size of the aspheric surface of the silicon lens from the first value to the set value;

[0050] S3: using the set turning tool, and turning the test piece of the same material as the silicon lens in the set form to obtain the distance that the blade surface of the set turning tool can keep the set turning accuracy, recorded as the accurate turning length;

[0051] S4: according to the total length and the accurate turning length, obtaining the number information and the position information of the tools to be replaced for completing turning;

[0052] S5: according to the number information and the position information, turning the aspheric surface of the silicon lens machined to the first value to obtain the silicon lens with aspheric surface having set precision.

[0053] The turning route in the set form specifically includes the following steps:

[0054] selecting the polar coordinate origin and the turning starting point on the aspheric surface of the silicon lens machined to the first value;

[0055] turning according to the typical Archimedes spiral trajectory, and the spiral trajectory equation is r=a+bθ, wherein a and b are real numbers, a is the distance between the polar coordinate origin and the turning starting point, and b is the distance between adjacent spiral lines.

[0056] The turning test of the test piece of the same material as the silicon lens in the set form to obtain the distance that the blade surface of the set turning tool can keep the set turning accuracy specifically includes the following steps:

[0057] turning the test piece from the center to the edge according to the typical Archimedes spiral trajectory;

[0058] observing the test piece during turning to obtain the mutation point of the turning accuracy of the surface of the test piece;

[0059] obtaining the distance between the turning starting point and the mutation point.

[0060] The distance between the turning starting point and the mutation point is obtained specifically by the following steps:

[0061] according to the following formula, converting the polar coordinates of the mutation point into Cartesian coordinates,

[0062] x=r·cos(θ)

[0063] y=r·sin(θ)

[0064] wherein r and θ are the polar coordinates of the mutation point, and x and y are the corresponding Cartesian coordinates;

[0065] According to the following formula, the number of turns of the mutation point in the trajectory of the Archimedes spiral line from inside to outside is obtained,

[0066] revs o =(o / f) / 2

[0067] Wherein, o represents the distance between the mutation point and the origin of the polar coordinates, f=2πb, indicating the pitch of the spiral;

[0068] According to the following formula, the corresponding angle of the mutation point in the Archimedes spiral line is obtained,

[0069] DEGREE o =revs o *360°;

[0070] According to the following formula, the distance between the turning point and the mutation point is obtained,

[0071]

[0072] The turning test of the test piece with the same material as the silicon lens material is carried out in the set form to obtain the distance that the set turning tool blade surface can maintain the set turning accuracy, which further includes the following steps:

[0073] The above test is carried out for many times, and a plurality of test values of the distance that the set turning tool blade surface can maintain the set turning accuracy are obtained respectively;

[0074] The arithmetic mean of a plurality of test values is calculated to obtain the distance that the set turning tool blade surface can maintain the set turning accuracy.

[0075] The number information and the position information of the tool to be replaced for completing turning are obtained according to the total length and the accurate turning length, and the specific steps include the following steps:

[0076] According to the following formula, the number information of the tool to be replaced for completing turning is obtained,

[0077]

[0078] Wherein, L is the total length, ceil represents the integer, such as ceil(4.1)=5;

[0079] According to the following formula, the position information of the tool to be replaced is obtained,

[0080]

[0081] D i =2*f*β i / 360°

[0082] wherein D i is the radial position information of the mutation point on the Archimedes spiral line, β i

[0083] is the turning length of i*L i on the Archimedes spiral line.

[0084] The following takes the processing of a single crystal silicon material optical lens with a caliber of D=76mm as a specific description.

[0085] First step: according to the same typical Archimedes spiral trajectory along the center to the edge turning, the spiral trajectory equation is the following formula, and f=2πb=1 at this time.

[0086] r=0.1592θ.

[0087] Second step: adopt microscope to test the processing surface, the turning direction is from the center to the edge, and the turning surface quality mutation position O=36mm is obtained. According to the Archimedes spiral trajectory mode, the conversion relationship of Cartesian coordinates (x-y) and polar coordinates (r-θ) and mathematical analysis, the turning length before the diamond tool wear can be calculated.

[0088] x=r*cos(θ)=0.1592θ*cos(θ)

[0089] y=r*sin(θ)=0.1592θ*sin(θ)

[0090] revs o =(o / f) / 2=18

[0091] DEGREE o =revs o *360°=6480°

[0092]

[0093] wherein x, y are Cartesian coordinates; r, θ are polar coordinates; O is the diameter of the turning surface mutation position; revs is the number of Archimedes spiral turns at the mutation position; DEGREE is the Archimedes spiral rotation angle of the mutation position O; L o is the Archimedes spiral arc length, that is, the turning length before the tool wear.

[0094] Third step: according to the turning parameters, the total turning length L=4.537m and the turning spiral rotation angle DEGREE=13680° in the processing of the silicon lens with a caliber of D=76mm are calculated according to the following formula for the large caliber silicon lens.

[0095] revso = (o / f) / 2 = 38

[0096] Fourth step: Calculate the number of tools needed to turn the caliber of the lens, the Archimedes spiral rotation angle β when each tool is replaced according to the following formula i According to the following formula, the radial position D of the tool wear when the silicon lens with an exit caliber of D is continuously turned i See Table 1.

[0097]

[0098]

[0099] D i = 2*f*β i / 360°

[0100] Table 1: Replacement position of the tool for turning the silicon lens with a caliber of 76mm

[0101]

[0102]

[0103] In the above embodiment, a large-caliber silicon lens turning machining process method of the present application is adopted, which is realized through the following points:

[0104] Through the first step: give the turning spiral trajectory;

[0105] Through the second step: calculate the turnable length of the tool according to the spiral trajectory to turn the silicon lens;

[0106] Through the third step: calculate the total length of the large-caliber silicon lens that needs to be turned according to the spiral trajectory;

[0107] Through the fourth step: according to the total length of the large-caliber silicon lens that needs to be turned in the third step and the length that can be turned before the tool wears in the second step, calculate the number of tools needed to turn the large-caliber silicon lens and the replacement position of the tool during the turning process.

[0108] The present scheme can obtain the turning track of the silicon lens by presetting the turning form of the silicon lens, and turning the silicon lens according to the track, so as to process the aperture of the aspheric surface from the first value to the set value. In addition, the turning test can be performed on the test piece made of the same material as the silicon lens, so as to obtain the maximum length that can be turned by the set turning tool under the premise of ensuring the turning precision, i.e. the accurate turning length. The ratio of the total length to the accurate turning length can obtain the position information and the number information of the set turning tool that needs to be replaced during the turning process. Finally, the set turning tool can be replaced according to the above position information and number information during the processing of the silicon lens, so as to keep the set turning tool for processing the silicon lens in the state of not being excessively worn, and the precision of the aspheric surface of the silicon lens processed thereby will also meet the set requirements. Theoretically, the present scheme is not affected by the pre-polishing degree of the silicon lens blank or the specific size of the silicon lens, and can ensure the turning precision of the silicon lens.

[0109] The above description is only the preferred embodiment of the present application and the explanation of the applied technical principles. Those skilled in the art should understand that the scope of the application involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by replacing the above features with the technical features disclosed in the present application (but not limited to) having similar functions.

Claims

1. A large-diameter silicon lens aspherical surface turning method, characterized by, The method comprises the following steps: processing the aspheric surface of a silicon lens blank to a first value, which is greater than a set value of the aspheric surface of the silicon lens after turning; selecting a turning route of a set form and calculating the total length of the turning track formed by turning the aspheric surface of the silicon lens from the first value to the set value; using a set turning tool and turning a test piece of the same material as the silicon lens in the set form to obtain the distance that the blade surface of the set turning tool can maintain the set turning accuracy, which is recorded as the accurate turning length; obtaining the number information and the position information of the turning tools to be replaced according to the total length and the accurate turning length; turning the silicon lens whose aspheric surface is processed to the first value according to the number information and the position information to obtain a silicon lens with an aspheric surface of a set accuracy.

2. The large aperture silicon lens aspherical surface turning method according to claim 1, wherein The step of selecting the turning route of the set form comprises the following steps: selecting a polar coordinate origin and a turning starting point on the aspheric surface of the silicon lens processed to the first value; turning according to a typical Archimedes spiral track, and the spiral track equation is r=a+bθ, wherein a and b are real numbers, a is the distance between the polar coordinate origin and the turning starting point, and b is the distance between adjacent spiral lines.

3. The large aperture silicon lens aspherical surface turning method according to claim 2, wherein The step of turning the test piece of the same material as the silicon lens in the set form to obtain the distance that the blade surface of the set turning tool can maintain the set turning accuracy comprises the following steps: turning the test piece from the center to the edge according to the typical Archimedes spiral track; observing the test piece during turning to obtain the mutation point of the turning accuracy of the surface of the test piece; obtaining the distance between the turning starting point and the mutation point.

4. The large aperture silicon lens aspherical surface turning method according to claim 3, characterized in that, The step of obtaining the distance between the turning starting point and the mutation point comprises the following steps: converting the polar coordinates of the mutation point into Cartesian coordinates according to the following formula, x=r*cos(θ) y=r*sin(θ) wherein r and θ are the polar coordinates of the mutation point, and x and y are the corresponding Cartesian coordinates; obtaining the number of turns of the mutation point in the track of the Archimedes spiral from inside to outside according to the following formula, revs o = (o / f) / 2 wherein o represents the distance between the mutation point and the polar coordinate origin, and f=2πb represents the pitch; obtaining the corresponding angle of the mutation point in the Archimedes spiral according to the following formula, DEGREE o = revs o * 360°; obtaining the distance between the turning starting point and the mutation point according to the following formula, 5. The large aperture silicon lens aspherical surface turning method according to claim 1, wherein The step of turning the test piece of the same material as the silicon lens in the set form to obtain the distance that the blade surface of the set turning tool can maintain the set turning accuracy further comprises the following steps: performing the above test multiple times and obtaining multiple test values of the distance that the blade surface of the set turning tool can maintain the set turning accuracy; obtaining the distance that the blade surface of the set turning tool can maintain the set turning accuracy by calculating the arithmetic mean of the multiple test values.

6. The large aperture silicon lens aspherical surface turning method according to claim 4, wherein The number information of the tool to be replaced for completing the turning and the position information of the tool to be replaced are acquired according to the total length and the accurate turning length, and specifically include the following steps: The number information of the tool to be replaced for completing the turning is acquired according to the following formula, Wherein, L is the total length; The position information of the tool to be replaced is acquired according to the following formula, D i = 2 * f * beta i / 360° wherein D i is the radial position information of the mutation point on the Archimedes spiral line, β i is the corresponding angle on the Archimedes spiral line when the turning length is i*L i .

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