CN111497043A - Method for manufacturing magnesium fluoride wave plate element - Google Patents

Abstract

The invention provides a manufacturing method of a magnesium fluoride wave plate element, which comprises the following steps: s1, cutting the magnesium fluoride crystal blank to obtain a rectangular strip blank with two sides a and b respectively, wherein a is along the (001) direction; s2, cutting the rectangular strip blank into rectangular sheets with the same thickness along the (100) plane; and S3, roughly grinding the rectangular thin sheet on an outer circle grinding machine, wherein the center point of the grinding machine corresponds to the center of the long edge of the blank sheet, and the diameter is ground to the required size. The invention adopts a pulling method to grow a magnesium fluoride monocrystal blank in a <100> direction, a (001) crystal face of the crystal is determined by a cross-shaped measuring method on a cylindrical surface by using an X-ray orientation instrument after processing a wave plate, then the crystal is directly sliced according to the (100) face according to the growth direction, and finally the crystal is processed to the required size by using an external grinding machine. The method is simple to operate, high in machining precision, capable of effectively improving the yield and reducing the cost of products.

Description

Method for manufacturing magnesium fluoride wave plate element

Technical Field

The invention belongs to the field of instruments and meters, and particularly relates to a manufacturing method of a magnesium fluoride wave plate element.

Background

The magnesium fluoride crystal is an excellent optical crystal material and can be used for manufacturing ultraviolet and infrared lenses, windows, polarization optical elements and the like. The magnesium fluoride crystal belongs to a tetragonal system, the lattice constants and expansion coefficients of a <100> direction (a axis or b axis) and a <001> direction (c axis) are greatly different, and a magnesium fluoride crystal blank grown by adopting a traditional Bridgman method can only select the c axis direction, otherwise the crystal has a serious cracking phenomenon. The magnesium fluoride crystal has birefringence and anisotropy, and when used as a polarizing element, it is necessary to utilize the birefringence characteristics, that is, the light passing direction is perpendicular to the crystal optical axis direction (c-axis). The wave plate is a typical polarization element, the magnesium fluoride crystal processing wave plate must be sliced according to a plane vertical to <100> (a axis), the growth direction of the wave plate is not consistent with the growth direction of a crystal blank, meanwhile, the polarization element requires that the deviation of the crystal orientation is less than 10 minutes for the orientation precision and the processing precision, the current processing method is to cut the plane first and then grind a platform, the method has low precision and large orientation error, the platform is easy to generate the condition of angular deviation when being processed, and the yield is greatly reduced.

Disclosure of Invention

The invention provides a processing method of a polarization element, aiming at solving the problems of large orientation deviation and low yield of the existing magnesium fluoride wave plate.

To achieve the above object, the present invention provides a method for manufacturing a magnesium fluoride wave plate element, comprising the steps of:

s1, cutting the magnesium fluoride crystal blank to obtain a rectangular strip blank with a short side a and a long side b, wherein the length of a is the diameter of the finished wave plate plus 0-1 mm along the (001) direction on the cylindrical surface of the crystal, and the length of b is the diameter of the finished wave plate plus 0.5-3 mm; s2, cutting the rectangular strip blank into rectangular sheets with the same thickness along the (100) plane; and S3, roughly grinding the rectangular sheet on an outer circle grinding machine, wherein the center point of the grinding machine corresponds to the center of the long edge of the blank sheet, and the diameter is ground to the required size.

Furthermore, the magnesium fluoride crystal blank is a magnesium fluoride single crystal with the <100> direction grown by a pulling method.

Further, S1 includes the steps of:

s11, finding out the (001) surface of the magnesium fluoride crystal blank, and grinding the (001) surface to be flat;

s12, adhering the (001) surface to a base of an inner circle cutting machine, and cutting a magnesium fluoride crystal blank to ensure that the thickness in the (001) direction is a, and a is the diameter of the finished wave plate plus 0-1 mm;

and S13, rotating the magnesium fluoride crystal blank by 90 degrees, and cutting the magnesium fluoride crystal blank again to obtain a rectangular strip blank with two sides a and b respectively, wherein b is the diameter of the finished wave plate plus 0.5-3 mm.

Further, an X-ray orientation instrument having a three-dimensional rotation stage is used for finding the (001) plane.

Furthermore, a (001) plane is accurately determined by adopting a cross orientation method.

Further, S2 includes the steps of:

s21, finding out the (100) surface of the magnesium fluoride crystal blank, and grinding the (100) surface to be flat; (ii) a

S22, adhering the (100) surface to a base of the inner circle cutting machine;

and S23, cutting the rectangular strip blank into rectangular sheets with the same thickness along the (100) plane.

Further, the (100) plane is found using an X-ray orientation machine with a three-dimensional rotating table.

Furthermore, a cross orientation method is adopted to accurately determine the (100) surface.

The method for manufacturing the magnesium fluoride polarization element (wave plate and the like) can be used for automatically completing the whole process by a machine without manual operation and repair in the later period, has simple operation method and high orientation precision, greatly reduces the labor cost in the processing process and improves the production and processing efficiency.

The invention adopts a pulling method to grow a magnesium fluoride monocrystal blank in a <100> direction, a (001) crystal face of the crystal is determined by a cross-shaped measuring method on a cylindrical surface by using an X-ray orientation instrument after processing a wave plate, then the crystal is directly sliced according to the (100) face according to the growth direction, and finally the crystal is processed to the required size by using an external grinding machine. The method is simple to operate, high in machining precision, capable of effectively improving the yield and reducing the cost of products.

Drawings

FIG. 1 is a schematic representation of a magnesium fluoride waveplate element made in accordance with the present invention.

FIG. 2 is a schematic diagram of the processing of a blank of a magnesium fluoride waveplate element of the present invention.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the invention, as detailed in the appended claims. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

It is to be understood that although the terms first, second, third, etc. may be used herein to describe various information, these information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present invention. The word "if" as used herein may be interpreted as "at … …" or "when … …" or "in response to a determination", depending on the context.

The present invention will be described in detail below by way of examples.

Take the magnesium fluoride wave plate with the diameter of 25.4 × 2mm and the platform width of 10 +/-3 mm as an example:

① selecting a crystal blank of magnesium fluoride grown by Czochralski method in the <100> direction, fixing the crystal blank on an X-ray orientation apparatus having a three-dimensional rotary table, finding out the position of the (001) plane 1 on the cylindrical surface by rotating the crystal, grinding the plane, and accurately determining the (001) plane 1 by the cross orientation method, i.e. the angle between the 4 directions of the cross and the theta angle of the crystal (001) plane 1 of magnesium fluoride (when the diffraction angle is the angle between the line of the advancing direction and the normal when the wave is diffracted), i.e. the angle at which the light path changes when the light is diffracted, e.g. in the X-ray diffractometer, we use 2theta (2 theta) as the diffraction angle, i.e. the angle at which the direction is changed after the X-ray is diffracted because 2theta (2 theta) is the angle at which the direction is changed when the wave is diffracted), then sticking the (001) plane 1 on the base of an internal circle cutting machine, cutting the magnesium fluoride crystal blank into pieces, ensuring the thickness of the <001> direction 25.5mm, then placing the crystal blank in the rotation direction until the angle is changed from the angle, and cutting the crystal blank is cut into a wafer, and cutting the wafer is carried out the wafer by rotating the method of the four times when the angle of the crystal blank, i.e. the crystal, and the angle of the crystal blank, and the angle of the crystal blank, i.e. the crystal blank, and the crystal blank, wherein the angle of the crystal blank are respectively, the crystal blank, the angle of the crystal blank is calculated as the angle of the crystal blank are respectively, the angle of the crystal blank is calculated as the angle of

② placing the cut crystal blank block on an X-ray orientation instrument again to precisely determine a (100) plane, grinding the plane to be flat, wherein the orientation method is the same as that of the (001) plane 1, adopting a cross orientation method, finally finding out a plane with 4 directions of cross which are the same as the theta angle of the (100) plane through the rotation of a rotary table, adhering the plane on the base of an inner circle cutting machine, and cutting a rectangular slice with the thickness of 2mm along the (100) plane;

③ roughly grinding the rectangular magnesium fluoride blank sheet on an excircle grinding machine, finding out the central point o of the blank (the central point of the blank is the center of the rectangle with a as the short side and b as the long side) by using a square die of 26.5mm, grinding the excircle corresponding to the center of the fixture of the excircle grinding machine, grinding the diameter to 25.4mm, and then obtaining the magnesium fluoride wave plate element after cleaning (as shown in figure 1) because the two sides of the rectangle are unequal and the short side of the rectangle with 25.5mm is a platform with 10 +/-3 mm.

The a side, the b side and the center point o involved in the rough machining process of the magnesium fluoride wave plate element are shown in fig. 2.

Comparative example

The comparative example is used for manufacturing the magnesium fluoride wave plate according to the prior art, the prior art mainly cuts out the wave plate firstly and then grinds the platform, and the specific process is as follows:

take the magnesium fluoride wave plate with the diameter of 25.4 × 2mm and the platform width of 10 +/-3 mm as an example:

①, accurately determining a (001) surface 1 by a cross orientation method, namely, angles in 4 directions of the cross are all the same as the angle theta of the (001) surface 1 of the magnesium fluoride crystal, then adhering the (001) surface 1 to a base of an inner circle cutting machine, cutting a magnesium fluoride crystal blank block, ensuring that the thickness in the (001) direction is 25.5mm of the diameter of a finished wave plate, then rotating the blank by 90 degrees, cutting again according to the distance of 26.5mm, and finally obtaining a rectangular strip blank with two sides respectively being a and b, wherein the length of a is 25.5mm, and the length of b is 26.5 mm;

② placing the cut crystal blank block on an X-ray orientation instrument again to accurately determine a (100) surface, wherein the orientation method is the same as that of the (001) surface 1, adopting a cross orientation method, finally finding out a plane with 4 directions of cross which are the same as the theta angle of the (100) surface through the rotation of a rotary table, adhering the plane on the base of an inner circle cutting machine, and cutting a rectangular slice with the thickness of 2mm along the (100) surface;

③ roughly grinding the rectangular magnesium fluoride blank on an excircle grinding machine, finding out the center point of the blank according to a square die with 26.5mm by 26.5mm, grinding the excircle corresponding to the center of the excircle grinding machine fixture, grinding the diameter to 25.4mm, then grinding the 25.5mm rectangular short side, grinding a platform with 10 +/-3 mm, and cleaning to obtain the magnesium fluoride wave plate element.

The magnesium fluoride wave plates prepared in the examples and the comparative examples are subjected to quality detection, and the detection indexes comprise yield and processing efficiency, wherein the yield of the preparation method can reach 95.8% or more, and the yield of the preparation method in the comparative example is only 67.8%; the processing efficiency of the invention is more than doubled compared with the comparison.

Claims (8)

1. A manufacturing method of a magnesium fluoride wave plate element is characterized by comprising the following steps:

s1, cutting the magnesium fluoride crystal blank to obtain a rectangular strip blank with a short side a and a long side b, wherein the length of a is the diameter of the finished wave plate plus 0-1 mm along the (001) direction on the cylindrical surface of the crystal, and the length of b is the diameter of the finished wave plate plus 0.5-3 mm;

s2, cutting the rectangular strip blank into rectangular slices with the same thickness as the finished product along the (100) plane;

and S3, roughly grinding the rectangular thin sheet on an outer circle grinding machine, wherein the center point of the grinding machine corresponds to the center of the long edge of the blank sheet, and the diameter is ground to the required size.

2. The method of claim 1, wherein the magnesium fluoride crystal blank is a <100> direction magnesium fluoride single crystal grown by a Czochralski method.

3. The method of claim 1, wherein the step of S1 comprises the steps of:

s11, finding out a (001) surface of the magnesium fluoride crystal blank, and grinding the (001) surface to be flat;

s12, adhering the (001) surface to a base of an inner circle cutting machine, and cutting the magnesium fluoride crystal blank to enable the thickness in the (001) direction to be a, wherein the a is the diameter of the finished wave plate plus 0-1 mm;

and S13, rotating the magnesium fluoride crystal blank by 90 degrees, and cutting the magnesium fluoride crystal blank again to obtain a rectangular strip blank with two sides of a and b respectively, wherein b is the diameter of the finished wave plate plus 0.5-3 mm.

4. The method of claim 3, wherein an X-ray orientation tool having a three-dimensional rotational stage is used to find the (001) plane.

5. The method of claim 4, wherein the (001) plane is precisely defined by a cross-orientation method.

6. The method of claim 1, wherein the step S2 includes the steps of:

s21, finding out a (100) surface of the magnesium fluoride crystal blank, and grinding the (100) surface to be flat;

s22, adhering the (100) surface to a base of the inner circle cutting machine;

and S23, cutting the rectangular strip blank into rectangular sheets with the same thickness along the (100) plane.

7. The method of claim 6 wherein an X-ray orientation tool having a three-dimensional rotational stage is used to find the (100) plane.

8. The method of claim 7, wherein the (100) plane is precisely defined by a cross-orientation.

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