CN114705403A - Decentration detection method for preparing lens - Google Patents

Abstract

The invention provides an eccentricity detection method of an optical lens, which comprises the steps of marking scratches at the same positions of an upper die and a lower die, namely the same positions of the upper die and the lower die, namely the upper die and the lower die and the left die and the right die; carrying out the mould pressing operation at normal temperature, wherein the normal temperature is 100-200 ℃; judging whether scratches at the positions of the upper die and the lower die are overlapped; when the die pressing operation is carried out, the upper die and the lower die can be judged to be accurate in position, and the die pressing operation can be carried out; when the alignment is not coincident, it can be determined that the positions of the upper and lower molds are inaccurate, and the positions of the upper and lower molds need to be adjusted to be aligned. The method of the invention does not need to be really positioned on the die and can be carried out at normal temperature by a relatively simple and convenient eccentricity detection method.

Description

Decentration detection method for preparing lens

technical field

The invention relates to an eccentricity detection method of an optical lens. In particular, it relates to a method for decentered detection of an optical lens by using nano-scratch.

Background technique

Optical lenses are widely used in security, vehicle, digital cameras, medical endoscopes and other fields. In the process of making an axisymmetric optical lens, an eccentricity error occurs when the optical axis of the lens does not coincide with the rotational symmetry axis of the lens. The detection and evaluation of the eccentricity error of the optical lens is an essential step in the manufacture of high-precision optical lenses, and the eccentricity error of the optical lens directly affects the imaging quality in the final use process. The detection method of the eccentricity error is to drive the lens to rotate to determine the rotation axis of the lens, use an autocollimator to project a cross reticle parallel beam, focus on a certain focus by the lens to be detected, and then use another autocollimator with an appropriate objective lens to This focus is introduced into the eyepiece or CCD camera to observe the reflected cross line. If the beam axis deviates from the mechanical rotation axis of the lens, the cross line observed by the eyepiece or the screen will rotate around a certain center, and the radius of rotation is the lens after geometric conversion. eccentricity.

In order to facilitate the detection of the eccentricity of the optical lens, the method adopted in CN 207730426U includes providing a lens eccentricity test frame, a bearing plate is placed on the worktable, a vertical cylinder is arranged on the bearing plate, and the upper end of the cylinder is rotatably connected There is a boss for supporting the lens, the boss is provided with a through slot vertically penetrating the boss and the cylinder, and the bearing plate is provided with a driving member for driving the boss to rotate; CN113588215A provides an optical lens detection The eccentric instrument includes two autocollimators and a base, on which a light source base and a detection base are arranged horizontally opposite to each other, wherein one of the autocollimators is set on the light source base, and the other The auto-collimator is arranged on the detection base, and the axes of the light sources of the two auto-collimators are relatively collinear; the light source base is provided with a horizontal support lens toward the detection base for self-collimation The light source base is provided with a driving frame relative to the carrier, and the driving frame is provided with a transmission component for driving the lens to rotate around its own geometric axis relative to the carrier.

By adopting the technical solution of the prior art, the operator places the lens to be tested on the carrier, and the carrier supports the lens horizontally along the axial direction of the lens, which is beneficial to improve the stability of the placement and rotation of the rod lens and other cylindrical lenses, and starts the transmission. The component drives the lens to rotate around its own geometric axis, activates the transmission lens of the auto-collimator on one side of the light source base, and the other auto-collimator observes that the transmission beam axis rotates around a certain center, thereby detecting the eccentricity of the lens. These methods are all direct detection methods.

The disadvantage of using direct inspection is that positioning on the mold can damage the wafer. There is a need for a relatively simple eccentricity detection method that does not require actual positioning on the mold and can be performed at room temperature.

SUMMARY OF THE INVENTION

The invention relates to an eccentricity detection method of an optical lens. In particular, it relates to a method for decentered detection of an optical lens by using nano-scratch.

The invention provides an eccentricity detection method for preparing a lens. Before the heating step of molding the optical lens, scratches are drawn on the same position of the surfaces of the upper and lower molds coated with the graphene-like layer; the upper and lower molds are heated with electricity; The molding operation is performed at room temperature, and the glass ball or PVC plastic substrate is molded; after molding, cooling and demoulding are performed, and it is judged whether the scratches on the upper and lower molds overlap or fit; The position is accurate; when the upper and lower molds do not coincide or do not fit, adjust the position of the upper and lower molds.

Another aspect of the present invention provides an eccentricity detection method, wherein the upper and lower molds are silicon molds, and the silicon mold is composed of a silicon mold core and a mold steel mold base.

Another aspect of the present invention provides an eccentricity detection method, wherein the upper and lower molds are made of stainless steel, such as 45 steel and SUS304 steel; the PVC plastic substrate is a transparent plastic substrate with a thickness of 0.3-0.8 mm.

Another aspect of the present invention provides an eccentricity detection method, wherein the glass ball is an optical glass such as borosilicate glass, silicate glass, phosphoric acid glass, and lanthanide glass.

A further aspect of the present invention provides an eccentricity detection method, wherein on the premise of maintaining the integrity of the silicon wafer, the heating process from normal temperature to the glass melting point (Tg) is completed within 30 seconds, and the temperature difference between the glass ball and the silicon mold core is less than 10 degrees.

Another aspect of the present invention provides the eccentricity detection method, wherein the normal temperature for the molding operation of the glass ball is 100-200 degrees; the normal temperature for the molding operation of the PVC plastic substrate is room temperature.

Another aspect of the present invention provides an eccentricity detection method, wherein the scratches are in the shape of a circle or a triangle in the order of nanometers to millimeters, wherein a center-symmetrical centering method is used for the circle; and a triangle is used for the triangle. The way the axes on which the three sides lie are aligned.

Another aspect of the present invention provides an eccentricity detection method, wherein the circles are single circles or concentric circles with the same shape of the upper and lower molds, or concentric circles with different shapes of the upper and lower molds.

Another aspect of the present invention provides an eccentricity detection method, wherein the heating step is to complete the heating target under the process conditions of a power of 5kw and a time of about 150 seconds.

In the method of the present invention, the material of the upper and lower molds is silicon carbide, which replaces the expensive tungsten carbide material used in traditional equipment, and a graphene-like (CBG) composite coating is deposited on the surface of the silicon mold to prepare a micro free-form surface optical element. Coating materials for rapid surface heating and for thermoforming processes, resulting in significant cost reductions. And because the entire cavity does not need to be heated, the mold base can be made of mold steel, which greatly reduces the cost of the entire mold. After the eccentricity detection method of the present invention is used to accurately judge whether the upper and lower molds can be centered, the lens produced by molding has higher yield and quality. The eccentricity detection method provided by the present invention can improve the yield of the optical lens on the basis of controlling the cost of the mold to a lower level.

Description of drawings

In order to describe the technical solutions in the embodiments of the present invention more clearly, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some examples of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without any innovative work.

Figure 1(a) is a schematic diagram of the pressing steps in the compression molding method of the present invention.

Figure 1(b) is a schematic diagram of the heating step in the compression molding method of the present invention.

FIG. 2 is a flow chart of the eccentricity detection method of the present invention.

FIG. 3 is a schematic diagram of an embodiment of the eccentricity detection method of the present invention.

FIG. 4 is a schematic diagram of an embodiment of the eccentricity detection method of the present invention.

FIG. 5 is a cross-sectional view of an upper and lower mold and an effect diagram of mold overlapping according to an embodiment of the eccentricity detection method of the present invention.

FIG. 6 is an experimental diagram of an embodiment of the eccentricity detection method of the present invention.

FIG. 7 is a cross-sectional view of the upper and lower molds and an effect diagram of the overlapping of the molds of another embodiment of the eccentricity detection method of the present invention.

FIG. 8 is a cross-sectional view of an upper and lower mold and an effect diagram of mold nesting according to still another embodiment of the eccentricity detection method of the present invention.

Detailed ways

The specific embodiments of the present invention will now be described with reference to the corresponding drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments shown herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully describe the scope of the invention to those skilled in the art. The phraseology used in the detailed description of the embodiments illustrated in the drawings should not be used to limit the invention.

Figure 1(a) is a schematic diagram of the pressing steps in the compression molding method of the present invention. In the heating step, a glass product to be pressed, such as a glass ball 103, is placed on the lower mold 102. The type of glass that can be used is not particularly limited, and a known glass can be selected according to the application. For example, optical glass, such as borosilicate glass, silicate glass, phosphoric acid glass, and lanthanide glass, is mentioned. The motor (not shown) drives the lower mold 102 to rise, and the lower mold 102 is heated with a voltage, thereby transferring heat to the glass ball 103, so that the temperature of the glass ball 103 rises to the transition temperature (Tg) of the glass and above; the pressing step, The motor of the lower mold 102 continues to drive the lower mold 102 to rise, while carrying the glass ball 103 for displacement, so that the glass ball 103 contacts the upper mold 101 to complete the pressing process; in the annealing and cooling step, slow annealing is performed, and the formed lens is processed in the forming mold. Preliminary annealing treatment to release internal stress; take out the annealed forming lens from the forming mold, place it on a cooling plate and cool it to room temperature separately; in the mold taking step, remove the cooled molded product from the upper mold 101 and the lower mold 102 to get out. The material of the upper and lower molds is silicon carbide, which replaces the expensive tungsten carbide material used in traditional equipment, and a graphene-like (CBG) composite coating is deposited on the surface of the silicon mold for the preparation of micro free-form optical elements, realizing rapid surface heating. And used for the coating material of the hot pressing forming process, thus greatly reducing the cost.

In addition, traditional equipment uses infrared heating to heat the entire molding cavity to a high temperature before molding, so it takes a long time and consumes a lot of energy. For example, when the power is 20kw, the heating time is about 900 seconds. In the present invention, the graphene-like coating can be heated in a short time only by energizing the graphene-like coating to rapidly heat up the coating, thereby saving time and energy consumption. And because the entire cavity does not need to be heated, the mold base can be made of mold steel, which greatly reduces the cost of the entire mold. Figure 1(b) is a schematic diagram of the heating step in the compression molding method of the present invention. The upper and lower mold surfaces are coated with a graphene-like coating. The upper and lower molds are heated by electricity, and the glass ball is molded, and finally the finished product is obtained by cooling and demoulding. Since a single coating is heated without heating the entire cavity, the heating target can also be achieved under process conditions such as a power of 5kw and a time of about 150 seconds. The overall heating efficiency is improved.

In addition, the tungsten carbide mold used in the traditional technology is composed of a tungsten carbide mold core and a tungsten carbide mold base. The silicon mold of the present invention is composed of a silicon mold core and a mold steel mold base, and the cost gap between the two is dozens of times. Therefore, Using the method of the present invention can significantly reduce the production cost.

FIG. 2 is a flow chart of the eccentricity detection method of the present invention. In step 201, scratches are drawn at the same position of the upper and lower molds, that is, the upper and lower/left and right positions are the same; in step 202, the molding operation is performed at normal temperature, and the normal temperature of the molding operation for the glass balls described here is 100 The temperature of -200 degrees; the normal temperature for the molding operation of the PVC substrate is room temperature; in step 203, it is judged whether the scratches on the upper and lower molds are overlapped or nested; when they overlap or nest, in step 204, it can be concluded that the upper and lower mold positions If it is accurate, the molding operation can be performed; when it is not overlapped or not fitted, in step 205, it can be determined that the upper and lower molds are inaccurate, and the positions of the upper and lower molds need to be adjusted to align them.

The molding operation is performed at room temperature, and an important material, plexiglass (Polymethyl methacrylate, abbreviated as PMMA), is used as an example. PMMA is an important thermoplastic developed earlier, because of its good light transmittance, low price, and the material is often used in hot embossing. When the motor is heated, the micro-cylindrical structure must reach a certain height to form a spherical surface; when cooling, the PMMA has a vertical structure, and its thermal expansion coefficient is much larger than that of the mold material itself, so it is easy to shrink the PMMA and squeeze it into the mold. Affect the demoulding effect. Therefore, it is necessary to select a reasonable temperature coefficient during the molding process. On the premise of maintaining the integrity of the silicon wafer, the heating process from room temperature to the glass melting point (Tg) can be completed within 30 seconds, and the temperature difference between the glass and the mold core is less than 10 degrees. The temperature coefficient of hot pressing suitable for PMMA should be around 100-200 degrees. And polycarbonate plexiglass, which can be used as lens optical material, has a temperature resistance of 130-150 °C. If medium heat-resistant plastics (specific varieties: PP, PVF, PVDC, PSF, PPO and PC, etc.) are used instead of fragile glass balls for experiments, the thermal deformation temperature is also between 100-200 °C. The reason for the normal temperature is that the assembly error can be estimated at normal temperature, and the assembly error that is easily generated under high temperature operation can be reduced.

FIG. 3 is a schematic diagram of an embodiment of the eccentricity detection method of the present invention. The upper mold 301 and the lower mold are respectively provided with logos; the logos of the upper and lower molds overlap to form a coincident logo 303 ; when the logos of the upper and lower molds do not overlap, the upper and lower molds need to be further adjusted. The eccentricity measurement method includes the following steps: in step 201, a glass knife made of diamond is used on the lower mold, and the glass ball on the lower mold (which can be replaced by a transparent plastic plate with a melting point of 100-200 degrees) is drawn as shown in Figure 301. and make a scratch of the same size on the corresponding position of the upper mold (the size of the scratch is on the order of nanometers), as shown in Figure 302. In step 202, a molding operation is performed at normal temperature. In step 203, it is judged whether the scratches of the upper and lower molds overlap. If they overlap, the effect as shown in Figure 303 should appear, and it can be indirectly determined that the upper and lower molds are positioned accurately without adjustment. As shown in Figure 304, it can be judged that the upper and lower mold positions are wrong and need to be readjusted.

FIG. 4 is a schematic diagram of an embodiment of the eccentricity detection method of the present invention. The upper and lower mold materials are made of stainless steel, such as 45 steel and SUS304 steel; PVC transparent plastic substrates are used as molding objects, and the PVC transparent plastic substrates can be made of materials with a thickness of 0.3-0.8 mm. A certain mark, such as a circle, a triangle, etc., is engraved on the center point of the upper and lower molds. In this embodiment, a circle mark is used; the method of this embodiment adopts the method of engraving at the center point, and the four-corner pair as shown in FIG. 3 can also be used. in the way. In this embodiment, a center-symmetrical centering method is adopted. For example, if the mark of a triangle is used, the axes on which the three sides of the triangle are located need to be aligned.

FIG. 5 is a cross-sectional view of an upper and lower mold and an effect diagram of mold overlapping according to an embodiment of the eccentricity detection method of the present invention. As shown in FIG. 5 , the marks of the circle are respectively drawn on the corresponding positions of the upper and lower molds. When the upper and lower molds are overlapped, the marks on the molds are overlapped.

FIG. 6 is an experimental diagram of an embodiment of the eccentricity detection method of the present invention. The photo of the real object 601 is the traces of the upper and lower molds basically pressed out of the PVC plastic, and did not penetrate the substrate. Enlarging the physical object 602, it can be seen that the marks of the upper and lower molds do not overlap, and there is a gap between the upper and lower circles. Therefore, it is necessary to adjust the positional relationship between the upper and lower molds.

FIG. 7 is a cross-sectional view of the upper and lower molds and an effect diagram of the overlapping of the molds of another embodiment of the eccentricity detection method of the present invention. As shown in FIG. 7 , the same concentric circle marks are respectively drawn on the corresponding positions of the upper and lower molds. When the upper and lower molds overlap, the marks on the molds overlap.

FIG. 8 is a cross-sectional view of an upper and lower mold and an effect diagram of mold nesting according to still another embodiment of the eccentricity detection method of the present invention. As shown in FIG. 8 , different concentric circle marks are respectively drawn on the corresponding positions of the upper and lower molds. When the upper and lower molds are overlapped, the marks on the molds fit with each other to form a complete concentric pattern.

When the centering of the upper and lower molds is accurately judged, the lenses produced by molding have higher yield and quality. Taking the eccentricity detection method provided by the overall technical solution of the present invention into consideration comprehensively, the yield of the optical lens can be improved on the basis of controlling the cost of the mold to a lower level.

According to the method provided by the technical solution of the present invention, the eccentricity is scratched at the same position of the upper and lower molds, the plexiglass is pressed at room temperature, and the traces are drawn on the upper and lower surfaces of the plexiglass to measure the eccentricity; or the upper and lower molds are scratched at the same position, The eccentricity is measured by pressing the plexiglass at a high temperature and making marks on the upper and lower surfaces of the plexiglass. Among them, nano-scale scratches are used to draw marks on the upper and lower plastic molds, and the operation can be performed in the temperature range of 100-200 ° C to measure the deviation between the upper and lower lines. Using this method to operate in the range of normal temperature, no real molding die is needed to avoid crushing the silicon wafer. The principle of this method is to use the refraction of light, so that the upper and lower structures can be seen, and the accurate value is calculated through the change of thickness, so as to realize the eccentricity detection of general devices, which is equivalent to providing an indirect The detection method can adjust the plastic parts in real time when the eccentricity is large, so as to ensure more accurate precision of the optical device.

Reference herein to "one embodiment," "an embodiment," or "one or more embodiments" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Also, please note that instances of the phrase "in one embodiment" herein are not necessarily all referring to the same embodiment.

The above descriptions are only used to illustrate the technical solutions of the present invention, and any person of ordinary skill in the art can modify and change the above embodiments without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be based on the scope of the claims. The present invention has been described above with reference to examples. However, other embodiments than those described above are equally possible within the scope of the present disclosure. Various features and steps of the present invention may be combined in other ways than described. The scope of the present invention is limited only by the appended claims. More generally, those of ordinary skill in the art will readily appreciate that all parameters, dimensions, materials and configurations described herein are for exemplary purposes and actual parameters, dimensions, materials and/or configurations will depend on the particular application or invention The application that the teaching is used for.

Claims (9)

1. A method for detecting decentering of a lens is provided,

before the heating step of compression molding the optical lens, marking scratches on the same positions of the surfaces of an upper mold and a lower mold coated with graphene-like layers;

electrifying and heating the upper die and the lower die;

performing mould pressing operation at normal temperature, and performing mould pressing on the glass ball or the PVC plastic substrate; cooling and demolding after die pressing, and judging whether scratches at the positions of the upper die and the lower die are overlapped or sleeved;

when the upper die and the lower die are overlapped or sleeved, judging that the positions of the upper die and the lower die are accurate;

when the upper die and the lower die are not coincident or are not sleeved, the positions of the upper die and the lower die are adjusted.

2. The eccentricity detection method as set forth in claim 1, wherein said upper and lower molds are silicon molds composed of a silicon core and a mold steel frame.

3. The eccentricity detection method as set forth in claim 1, wherein said upper and lower dies are made of stainless steel such as 45 steel, SUS304 steel; the PVC plastic substrate is a transparent plastic substrate with the thickness of 0.3-0.8 mm.

4. The eccentricity detection method as set forth in claim 1, wherein said glass beads are optical glass such as borosilicate glass, silicate glass, phosphoric acid glass, or lanthanide glass.

5. The eccentricity detection method as claimed in claim 2, wherein the temperature rise from room temperature to the melting point (Tg) of the glass is completed within 30 seconds while the integrity of the silicon wafer is maintained, and the temperature difference between the glass ball and the silicon core is less than 10 degrees.

6. The eccentricity detection method as claimed in claim 1, wherein the molding operation of said glass spheres is performed at a temperature of 100-200 ℃; and the normal temperature for carrying out mould pressing operation on the PVC plastic substrate is room temperature.

7. The eccentricity detection method as claimed in claim 1, wherein the scratches are in the shape of a circle, triangle, on the order of nanometers to millimeters, wherein a center symmetric centering manner is adopted for the circle; and for the triangle, the axes of three sides of the triangle are aligned.

8. The eccentricity detection method as set forth in claim 6, wherein the circular shape is a single circle or concentric circles having the same shape of the upper and lower molds, or concentric circles having different shapes of the upper and lower molds.

9. The eccentricity detection method as claimed in claim 1, wherein said heating step is performed under a process condition of a power of 5kw for about 150 seconds.

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