I. Blank Preparation

1. Material Selection and Cutting

   In accordance with material specifications on drawings, raw materials including optical glass (e.g., K9, BK7) and crystals (e.g., CaF₂) are selected. Bulk glass is cut into blanks via internal/external circular cutting machines or laser cutting, with cutting margin controlled between 0.5 mm and 1 mm. Glass pieces are bonded into strips using adhesive strips, and preliminary spherical profiles are formed by a rounding machine.
2. Rough Grinding

   Loose abrasive grinding is carried out with W40–W28 diamond abrasives to eliminate surface bubbles and impurities, reducing surface roughness to the micrometer level. Fixtures adopt an upper-smaller-and-larger-below configuration (the diameter of the upper fixture is 5% smaller than the lower one). Oscillating grinding is adopted to avoid edge collapse and warping.

II. Fine Grinding and Polishing

1. Fine Grinding

   Rough-ground lens blanks are bonded onto lens carriers. Resin-bonded grinding wheels are used with progressively finer abrasives (from W40 down to W5), bringing surface roughness to the submicron level. Key controlled parameters: grinding pressure 0.2–0.5 kg/cm², coolant flow rate 200 ml/min, and temperature fluctuation ≤ ±1°C.
2. Traditional Polishing

   Pitch polishing tools are used together with cerium oxide or rouge polishing slurry. The polishing slurry pH ranges from 6 to 8; operating temperature is 25°C ±1°C, and relative humidity is maintained at 60–70%. A composite motion trajectory combining spiral paths and reciprocating swing is adopted. The peripheral linear speed is set 15–20% higher than the central speed to compensate edge effects.

III. Centering and Edge Trimming

1. Centering and Edge Grinding
   The optical centering method uses an autocollimator to align the optical axis of the lens with its mechanical axis, achieving decentration tolerance ≤5 μm. Diamond grinding wheels are used for outer diameter machining; wheel grit size is matched to glass hardness (for instance, 400# wheels for glass with Hv 500 hardness).

IV. Post-Processing

1. Optical Coating

   Vacuum evaporation is performed under vacuum pressure of 10⁻⁴ Pa. Materials such as magnesium fluoride (MgF₂) and titanium dioxide (TiO₂) are deposited to form anti-reflection coatings, enabling transmittance up to 99.5%. Film thickness is monitored by a crystal oscillator system with precision of ±2 nm. A typical coating stack adopts a 4-layer λ/4 structure.
2. Cementing and Black Coating

   UV curing cementing: adhesive layer thickness is controlled within ±2 μm, and optical axis offset ≤3 μm. Light elimination treatment is implemented by coating non-optical surfaces with carbon black/graphite mixed paint, suppressing reflectance below 0.5%.

V. Inspection and Quality Control

VI. Process Characteristics and Technical Challenges

1. Environmental Requirements
   Workshop environment: constant temperature 22°C ±2°C, humidity 60% ±5%, and cleanliness Class 1000.
2. Technical Bottlenecks
   The yield rate of aspheric lenses manufactured via conventional processes stands at merely 60%, highly dependent on experienced technicians to adjust polishing tool deformation.
3. Development Trend
   Combination with ion beam figuring enables ultra-precision machining up to λ/50 accuracy.