Rapid manufacturing method of small-caliber silicon carbide reflector substrate

Abstract

The invention discloses a method for rapidly manufacturing a small-caliber silicon carbide reflector substrate, which comprises the following steps of: determining an optical surface type of a target reflector according to a design drawing of the target reflector, processing a concave surface type consistent with the surface type of the reflector on the surface of a die by adopting a single-point diamond turning technology, and forming the small-caliber silicon carbide reflector substrate by utilizing a glass die forming technology. Carrying out hot press molding on a thermoplastic resin material in the mold to obtain a convex surface type polishing head complementary to the surface type of the reflecting mirror, attaching the polishing head to a silicon carbide reflecting mirror blank, injecting a polishing solution, keeping the reflecting mirror blank fixed, driving the polishing head to rotate at a high speed, and carrying out surface contact type polishing on the surface of the reflecting mirror blank to obtain the silicon carbide reflecting mirror. And the surface quality of the polished reflector blank is detected, if the surface quality does not reach the standard, the mold is reprocessed according to the measured surface type, the method is repeated until the processing requirement is met, the special polishing heads complementary with the reflector surface type are prepared in batches through die forming, and the problem that the efficiency is low due to the fact that the sizes of the polishing heads are limited for the small-caliber reflectors is solved.

Description

Technical Field

[0001] This invention relates to the field of optical component manufacturing, specifically to a rapid manufacturing method for a small-diameter silicon carbide mirror substrate. Background Technology

[0002] Small-aperture mirrors are widely used in mobile phone lenses, security monitoring, vehicle imaging systems, infrared optical systems, and industrial precision optical equipment. To obtain a surface that meets optical performance requirements, the mirror substrate needs to be polished with ultra-precision. Silicon carbide is widely used as a mirror material due to its high specific stiffness and excellent thermal stability. However, silicon carbide materials prepared by reaction sintering are composed of a mixture of silicon carbide and free silicon, and the two have significant differences in hardness, making it difficult to obtain a uniform and smooth optical surface by direct polishing. Existing technology usually first rough polishes the silicon carbide substrate to a certain roughness, then deposits a dense silicon modification layer on its surface, and then fine polishes the modification layer to form an optical surface.

[0003] In the processing of small-diameter (usually referring to diameter less than 30mm) silicon carbide reflector substrates, traditional ultra-precision polishing uses a flexible polishing head to sweep the workpiece surface in a point contact or small area surface contact manner. Due to the small diameter of the reflector, in order to avoid interference between the polishing head and the edge of the mirror, a smaller polishing head must be used. This results in: (1) low removal rate per unit area and low processing efficiency; (2) micro polishing heads are easy to wear and have a short lifespan; (3) difficulty in achieving batch, stable and low-cost manufacturing. Summary of the Invention

[0004] To address the aforementioned technical problems, a rapid manufacturing method for small-diameter silicon carbide reflector substrates is provided. This technical solution solves the problems mentioned in the background technology, such as low unit area removal rate, low processing efficiency, easy wear and short life of micro-polishing heads, and difficulty in achieving batch, stable, and low-cost manufacturing.

[0005] To achieve the above objectives, the technical solution adopted by this invention is: a rapid manufacturing method for a small-diameter silicon carbide reflector substrate, comprising the following steps:

[0006] Step 1: Determine the optical surface shape of the target reflector based on its design drawings;

[0007] Step 2: Use single-point diamond turning technology to machine a concave surface on the mold surface that matches the surface shape of the reflector;

[0008] Step 3: Using glass molding technology, thermoplastic resin material is hot-pressed into the mold to obtain a convex polishing head that complements the surface of the reflective mirror.

[0009] Step 4: Place the polishing head against the silicon carbide mirror blank and inject polishing liquid, keep the mirror blank fixed, drive the polishing head to rotate at high speed, and perform surface contact polishing on the surface of the mirror blank.

[0010] Step 5: Inspect the surface quality of the polished mirror blank. If it does not meet the standard, reprocess the mold according to the measured surface shape, and repeat steps 2 to 4 until the processing requirements are met.

[0011] Preferably, the thermoplastic resin material is one of polyurethane or epoxy resin;

[0012] Preferably, the polishing head is mass-produced using the same mold;

[0013] Preferably, the reflector has a spherical or freeform surface.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] (1) By mass-producing a special polishing head that complements the surface shape of the mirror through molding, the problem of low efficiency caused by the limited size of the polishing head for small-diameter mirrors is solved.

[0016] (2) The polishing head is made of resin material, which is low in cost, easy to process, can be customized for complex surface shapes, and causes little damage to the silicon carbide substrate;

[0017] (3) Surface contact polishing improves processing uniformity and efficiency, and shortens the manufacturing cycle;

[0018] (4) The molds can be reused, and multiple batches can be produced in the same batch, achieving high-precision and high-consistency mass production;

[0019] (5) Applicable to the rapid manufacturing of complex small-diameter reflector substrates such as spherical and free-form surfaces. Attached Figure Description

[0020] Figure 1 This is an overall flowchart of the method of the present invention;

[0021] Figure 2 This is a schematic diagram of mold processing and forming.

[0022] Figure 3 A schematic diagram illustrating the machining process of a polishing head;

[0023] Figure 4 This is a schematic diagram showing the polishing state of the polishing head and the silicon carbide blank in contact. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example

[0026] Please refer to Figures 1-4 As shown, a rapid manufacturing method for a small-diameter silicon carbide mirror substrate includes the following steps:

[0027] Step 1: Determine the optical surface shape of the target reflector based on its design drawings;

[0028] Step 2: Use single-point diamond turning technology to machine a concave surface on the mold surface that matches the surface shape of the reflector;

[0029] Step 3: Using glass molding technology, thermoplastic resin material is hot-pressed into the mold to obtain a convex polishing head that complements the surface of the reflective mirror.

[0030] Step 4: Place the polishing head against the silicon carbide mirror blank and inject polishing liquid, keep the mirror blank fixed, drive the polishing head to rotate at high speed, and perform surface contact polishing on the surface of the mirror blank.

[0031] Step 5: Inspect the surface quality of the polished mirror blank. If it does not meet the standard, reprocess the mold according to the measured surface shape, and repeat steps 2 to 4 until the processing requirements are met.

[0032] The thermoplastic resin material is either polyurethane or epoxy resin;

[0033] The polishing heads are mass-produced using the same mold;

[0034] The reflector has a spherical surface.

[0035] Working Principle: Small-aperture reflectors are widely used in mobile phone lenses, security lenses, automotive imaging systems, infrared optical imaging systems, and industrial application lenses. To obtain a surface with optical characteristics, ultra-precision polishing of the optical component surface is required. Taking the manufacture of a 20mm diameter spherical silicon carbide reflector substrate as an example, firstly, based on the surface data output by the optical design software, the spherical equation is determined. Hard alloy is selected as the mold substrate, and a single-point diamond lathe is used to machine a spherical surface on its end face that perfectly matches the target reflector, with a surface accuracy PV value ≤ 0.5μm. Polyurethane granules are placed in the mold cavity, heated to 180℃, and subjected to 5MPa pressure for 10 minutes. After cooling, the mold is demolded to obtain a spherical resin polishing head. The silicon carbide blank is fixed in a fixture, and the polishing head is gently pressed against its surface. An alkaline polishing solution is applied, and the polishing head is rotated at 3000 rpm for 15 minutes. The polished surface is then inspected using a white light interferometer, yielding PV=1.2μm and RMS=0.15μm. Analysis revealed a slight concavity in the central area, leading to a fine adjustment of the mold surface (increasing the center height by 0.3μm). The polishing head is then re-pressed and polished. After the second polishing, the results meet the substrate requirements (PV≤1.0μm), completing the manufacturing process. This method allows for the continuous production of multiple polishing heads, shortening the polishing time per piece compared to traditional spot polishing and significantly improving surface consistency. The polishing process employs a full-surface contact method, with the polishing head simultaneously contacting the entire surface of the blank. This invention utilizes glass molding to mass-produce polishing heads suitable for small diameters, achieving rapid substrate manufacturing and improving the production efficiency of small-diameter reflectors.

[0036] By mass-producing specialized polishing heads that complement the surface shape of the reflector through molding, the problem of low efficiency caused by the limited size of polishing heads for small-diameter reflectors is solved. The polishing heads are made of resin material, which is low in cost, easy to process, and can be customized for complex surface shapes. It also causes little damage to the silicon carbide substrate. The surface contact polishing method improves the uniformity and efficiency of processing, shortens the manufacturing cycle, and the mold can be reused. Multiple batches can be produced in the same batch, achieving high-precision and high-consistency mass production. It is suitable for the rapid manufacturing of various complex small-diameter reflector substrates such as spherical and free-form surfaces.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A rapid manufacturing method for a small-diameter silicon carbide mirror substrate, characterized in that, Includes the following steps: Step (1): Determine the optical surface shape of the target reflector based on its design drawings; Step (2): Use single-point diamond turning technology to machine a concave surface on the mold surface that matches the surface shape of the reflector. Step (3): Using glass molding technology, thermoplastic resin material is hot-pressed into the mold to obtain a convex polishing head that complements the surface of the reflective mirror; Step (4): Place the polishing head against the silicon carbide mirror blank and inject polishing liquid, keep the mirror blank fixed, drive the polishing head to rotate at high speed, and perform surface contact polishing on the surface of the mirror blank; Step (5): Inspect the surface quality of the polished mirror blank. If it does not meet the standard, reprocess the mold according to the measured surface shape and repeat steps (2) to (4) until the processing requirements are met.

2. The rapid manufacturing method for a small-diameter silicon carbide mirror substrate as described in claim 1, characterized in that, The thermoplastic resin material is either polyurethane or epoxy resin.

3. The rapid manufacturing method for a small-diameter silicon carbide reflector substrate as described in claim 1, characterized in that, The polishing heads are mass-produced using the same mold.

4. The rapid manufacturing method for a small-diameter silicon carbide mirror substrate as described in claim 1, characterized in that, The reflector has a spherical or freeform surface.

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