Aspherical optical glass

Optical Lens Types

1. Double convex

2. One convex and one concave

3. One convex and one flat

4. Double concave

5. One concave and one flat (as shown in the figure)

   
   

Classification of Optical Lenses

Glasses with similar chemical composition and optical properties are also distributed in adjacent positions on the Abbe diagram. The Abbe diagram of Schott Glass Factory has a set of straight lines and curves, which divide the Abbe diagram into many areas and classify optical glasses; for example, crown glasses K5, K7, and K10 are in the K area, and flint glasses F2, F4, and F5 are in the F area. Symbols in glass names: F stands for flint K stands for crown B stands for boron BA stands for barium LA stands for lanthanum N stands for lead-free P stands for phosphorus.

Optical Cold Processing Procedures

milling → fine grinding → polishing → cleaning → edge grinding → coating → ink coating → gluing

1. Milling (barren folding/ball milling/rough grinding): The first step of lens grinding is to remove uneven bubbles and impurities on the lens surface (about 0.05-0.08mm), which plays a shaping role. As shown below:

Principle: As shown in the figure above, the cutting edge of the diamond grinding wheel passes through the vertex of the lens. The axis of the grinding wheel and the axis of the lens intersect at point 0. The axis of the grinding tool rotates around its own axis at high speed, and the lens rotates around its own axis at low speed. The envelope of the motion trajectory forms a spherical surface.

Abandoned folding processing equipment: QM0.

8A, manufacturer: Korea Times, no chamfering function, relatively low accuracy.

CG2.0, manufacturer: Korea Guangjin, has chamfering function and relatively high accuracy.

Measuring tools: center thickness detection measuring tool (micrometer)

2. Fine grinding (sand hanging): eliminate the damaged layer of the milled lens, reduce the concave and convex layer on the lens surface, and fix the R value (aperture, Newton ring)

Principle: The lens is in the sand hanging dish (made of diamond pellets selected according to the material), the sand hanging dish rotates at high speed along its own axis, and the lens rotates at high speed along its own axis and swings back and forth, as shown in the figure below. The diamond pellets grind the lens surface, thereby reducing the depth of the concave and convex layer on the lens surface, and further improving the accuracy of the curvature radius or flatness of the lens surface.

Process: Material collection → First sanding on one side → Second sanding on one side → First sanding on the second side → Second sanding on the second side → Sanding inspection → Flow into grinding

Sanding equipment: Small spherical single-piece sanding equipment; Large spherical single-piece sanding equipment. (As shown below)

Testing tools: center thickness testing gauge (micrometer); surface accuracy testing (original), as shown below:

The single-piece spring plate process (fine grinding) is shown below:

The multi-plate process (fine grinding) is shown below:

3. Polishing (grinding): Polish the finely ground lens once. This process is mainly to make the appearance better. Note: Some customers do two polishings, the first one is rough polishing and the second one is fine polishing. Most customers in the market only need one process.

4. Cleaning: Clean the polishing powder and residue on the surface of the polished lens to prevent agglomeration.

5. Edge grinding: Grind the original lens outer diameter to the specified outer diameter.

6. Coating: Coat the surface of the lens that needs to be coated with one or more layers of colored film or other film.

7. Inking: Coat the outer edge of the lens that needs to be coated with a layer of black ink to prevent reflection.

8. Gluing: Use glue to combine two lenses with opposite R values and the same outer diameter material. Special process: multi-piece processing (disc processing) and small spherical surface processing (20-axis equipment) wire cutting. Depending on the different production processes, the processes may vary slightly, such as the order of inking and gluing.

Special Processes in Lens Production

• Double coring

Scope of application: lenses with edge thickness less than 0.3mm after grinding

Purpose:  1. Increase edge thickness after grinding and reduce edge damage during grinding;

                    2. Improve aperture stability during grinding

• Coring after gluing

Scope of application: lenses that must be cored after gluing due to special requirements of the customer. If the customer does not specify, this process will not be arranged

Purpose:  1. Completely remove excess glue on the edge of the lens

                     2. There will be no bright lines after blackening (inking)

• Trimming lenses

The lens diameter is large (＞￠20mm) and the margin for trimming is large (＞3mm), and the edges can be trimmed after folding;

The lens diameter is small (＜￠20mm), the trimming margin is large (＞3mm), and the edge is trimmed after taking out the core;

The lens diameter is small (＜￠20mm), the trimming margin is small (＜3mm), and the core and trimming can be completed in one go.

Abrasive Materials and Grinding Process

• Abrasive Powder Types

• Grinding Fluid Characteristics

• Grinding Leather Specifications

• pH Value of Grinding Fluid

  
  

Quality Requirements for Grinding Processing

• Dimensions and Appearance Requirements

• Causes of grinding defects

1. Sand

2. Scars

The scratch and pit inspection level is given by two codes, such as: 10-5, 20-10, 80-50. The first code is the scratch number, which gives the maximum scratch width, as shown in the table below.

The second digit is the pit number, and it gives the maximum pit diameter, as shown in the table:

Appearance: American standard analysis