Lapping Fused Silica – Fused Silica (CTE 0.55 x 10^-6 /K, 185 nm – 2.5 um); Lapping to flatness 1 – 3 um. No minimum order; DFM review included with every RFQ.
Ask any process engineer what makes fused silica difficult and the answer is specific: its hardness and brittleness demand diamond tooling and controlled feeds. Our lapping line is tooled around exactly that – cast-iron lap plates with boron carbide and alumina slurries – holding flatness 1 – 3 um on parts from 0.2 – 40 mm thick.
Specification envelope
| Material | Fused Silica (JGS1 (UV), JGS2 (standard), JGS3 (IR)) |
|---|---|
| Thermal expansion (CTE) | 0.55 x 10^-6 /K |
| Service temperature | 1,100 C continuous |
| Transmission range | 185 nm – 2.5 um |
| Density | 2.20 g/cm3 |
| Knoop hardness | 500 kg/mm2 |
| Refractive index | 1.458 @ 587 nm |
| Stock thickness | 0.10 – 50 mm |
| Maximum blank size | 450 x 450 mm |
| Process | Lapping |
| Working tolerance | flatness 1 – 3 um |
| Minimum feature | thickness +/-0.003 mm |
| Surface finish | Ra 0.2 – 0.6 um matte |
| Thickness window | 0.2 – 40 mm |
| Edge condition | not applicable |
| RFQ inputs | PDF/DXF/STEP drawing, quantity brackets, surface and edge spec |
What the process holds
Lapping earns its place through restoring flatness and parallelism on plates and repairing bowed stock. Its boundary condition – lapped faces are translucent-matte; optical clarity requires a subsequent polish – is the first thing our DFM review checks.
Beyond this page, Fused Silica routinely runs through cnc machining, double-side polishing, etching, edge grinding in our shop – most real parts combine two or three of these steps.
Specification advice
The shop-floor rules that matter here:
- Material note: its hardness and brittleness demand diamond tooling and controlled feeds.
- Process boundary: lapped faces are translucent-matte; optical clarity requires a subsequent polish.
- 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.
Who orders this
The recurring buyers of lapping fused silica: optical sensors (sensor windows, filter caps, lens covers); mems devices (cap wafers, TGV substrates, motion-sensor lids); ccd inspection equipment (CCD cover plates, reference grids, stage glass). Background reading on the underlying material science: RP Photonics: fused silica.
The fastest route to a quote is geometry: use the 3D builder below, draw a dimensioned 2D drawing from it, or open the site-wide custom glass machining 3D + 2D builder for fully custom parts.
Related reading on this site: fused silica material guide, fused silica wafers 2-12 inch, LED groove cover glass.
Common questions
How does Fused Silica behave under heat?
CTE is 0.55 x 10^-6 /K and continuous service reaches 1,100 C continuous, which is what drives its use where near-zero thermal expansion matters.
What accuracy does lapping hold?
Flatness 1 – 3 um with minimum features of thickness +/-0.003 mm. Lapped faces are translucent-matte; optical clarity requires a subsequent polish.
What equipment runs the lapping work?
Cast-iron lap plates with boron carbide and alumina slurries.
Is there a minimum order for lapping fused silica?
No. Single prototypes are accepted, and pricing steps down at 10, 100 and 1,000 pieces.
Specifications on this page were last reviewed by our engineering team in August 2026.