Grinding Optical Glass – Optical Glass (CTE 7.1 x 10^-6 /K, 350 nm – 2.0 um); Grinding to flatness to 5 um over 100 mm. No minimum order; DFM review included with every RFQ.
grinding optical glass is a materials problem before it is a machining problem. Optical Glass has certified refractive index and dispersion and a Knoop hardness of 610 kg/mm2, so the grinding recipe – feeds, coolant, tooling – differs from what works on ordinary float glass. The line runs rotary surface grinders and double-disc machines with diamond wheels and holds flatness to 5 um over 100 mm.
Key parameters
| Material | Optical Glass (N-BK7, H-K9L and filter glass sets) |
|---|---|
| Thermal expansion (CTE) | 7.1 x 10^-6 /K |
| Service temperature | 400 C (Tg 557 C) |
| Transmission range | 350 nm – 2.0 um |
| Density | 2.51 g/cm3 |
| Knoop hardness | 610 kg/mm2 |
| Refractive index | 1.5168 @ 587 nm |
| Stock thickness | 0.30 – 50 mm |
| Maximum blank size | 300 mm diameter |
| Process | Grinding |
| Working tolerance | flatness to 5 um over 100 mm |
| Minimum feature | thickness to +/-0.005 mm |
| Surface finish | Ra 0.2 – 0.8 um |
| Thickness window | 0.3 – 60 mm |
| Edge condition | ground perimeter, squareness 0.02 mm |
| RFQ inputs | PDF/DXF/STEP drawing, quantity brackets, surface and edge spec |
Specification advice
Before sending the RFQ, check these against your drawing:
- Material note: index-certified blanks must be oriented and serialized through the shop to keep melt traceability.
- Process boundary: subsurface damage of 5 – 15 um must be budgeted and removed by polishing on optical faces.
- Over-specification is the quiet budget killer: a 20/10 scratch-dig face costs roughly three times an 80/50 face, so grade each surface individually.
For the complete framework, see the tolerance design guide and the holes and edges design guide.
What the process holds
Grinding earns its place through bringing thickness, flatness and parallelism into calibrated tolerance before polish. Its boundary condition – subsurface damage of 5 – 15 um must be budgeted and removed by polishing on optical faces – is the first thing our DFM review checks.
Beyond this page, Optical Glass routinely runs through cnc machining, lapping, ultrasonic machining, etching in our shop – most real parts combine two or three of these steps.
Application context
Orders for grinding optical glass cluster in scientific instruments (reference flats, cells, prism mounts, stage inserts); ccd inspection equipment (CCD cover plates, reference grids, stage glass); laser systems (windows, beam splitters, debris shields). Background reading on the underlying material science: RP Photonics: optical glass.
Dimensions still moving? Configure this part live in the 3D + 2D builder below, or open the full custom glass machining 3D + 2D builder to start from a blank canvas.
For adjacent specifications, see optical polishing capability, AR coated glass materials, ultra-thin quartz discs.
Buyer questions, answered
What equipment runs the grinding work?
Rotary surface grinders and double-disc machines with diamond wheels.
Is there a minimum order for grinding optical glass?
No. Single prototypes are accepted, and pricing steps down at 10, 100 and 1,000 pieces.
How fast can prototypes ship?
Machined prototypes ship in 5 – 10 working days. Coated or bonded parts add 1 – 2 weeks depending on queue slots.
What files do you need for a quote?
A dimensioned PDF plus DXF or STEP geometry. If only a sketch exists, our drawing review service formalizes it before quoting.
Do parts ship with inspection data?
Dimensional reports, surface certificates and material certs per melt are available; specify the level on the RFQ.
Specifications on this page were last reviewed by our engineering team in September 2026.