Technical Resources
Reference guides for specifying and sourcing precision optical components
Choosing the right substrate material is the first step in specifying a precision optical component. Key factors: transmission wavelength range, thermal expansion, mechanical hardness, and cost.
| Material | Transmission Range | Refractive Index | CTE (×10⁻⁶/°C) | Hardness HK | Primary Use Case |
|---|---|---|---|---|---|
| UV Fused Silica (JGS1) | 185 nm – 2.5 μm | 1.457 @ 633nm | 0.55 | 615 | UV/NIR lasers, general precision optics |
| H-K9L (≡ N-BK7) | 350 nm – 2.1 μm | 1.517 @ 587nm | 7.1 | 610 | Visible light, general purpose, cost-effective |
| Sapphire (Al₂O₃) | 200 nm – 5.5 μm | 1.755 @ 1 μm | 5.3 | 2000 | Harsh environment windows, high hardness |
| CaF₂ | 130 nm – 8 μm | 1.501 @ 193nm | 18.85 | 158 | Deep UV (ArF lithography), broadband IR |
| ZnSe | 0.6 – 16 μm | 2.403 @ 10.6 μm | 7.1 | 120 | CO₂ lasers (10.6 μm), mid-IR systems |
ZnSe and CaF₂ available on request. Contact us with your wavelength and application requirements.
Understanding optical specification notation lets you define exactly what you need — and avoid over-specifying tolerances that add cost without adding optical performance.
| Term | Notation | What It Means | Typical Values |
|---|---|---|---|
| Surface Quality | S/D (Scratch-Dig) | Scratch width in μm / Dig (pit) diameter in 0.01 mm. Per MIL-PRF-13830B. | 60-40 (commercial) → 20-10 (precision) → 10-5 (laser) |
| Surface Flatness | λ/N | Peak-to-valley deviation from a perfect flat, measured at 632.8 nm (He-Ne laser). | λ/4 (standard) → λ/8 → λ/10 (precision) |
| Parallelism | < N' (arcmin) or < N″ (arcsec) | Angular deviation between the two optical surfaces. Affects beam deviation and fringe visibility in interferometry. | < 3' (commercial) → < 1' → < 30″ (precision) |
| Clear Aperture (CA) | > N% | The fraction of the total diameter that meets all specified tolerances. The edge chamfer zone is excluded. | > 85% (standard) → > 90% (precision) |
| Centration (for lenses) | < N' (arcmin) | Angular deviation of the optical axis from the mechanical axis of the lens. Affects image quality and beam pointing. | < 3' (standard) → < 1' (precision) |
| Angle Tolerance (prisms) | < N' or < N″ | Deviation of a prism face angle from the nominal design angle. Critical for beam deflection accuracy. | < 3' (standard) → < 30″ (precision) |
Chinese optical manufacturers use domestic material grade designations. Use these tables to map Chinese grades to Schott, Hoya, Ohara, or Corning equivalents when verifying material compatibility.
Fused Silica / Synthetic Quartz
| Chinese Grade | Corning Equiv. | Heraeus Equiv. | OH Content | UV Cutoff | Notes |
|---|---|---|---|---|---|
| JGS1 | Corning 7980 | Suprasil® 1 / 2 | High (~1000 ppm) | ~185 nm | Best UV transmission; use for 193–355nm lasers |
| JGS2 | Corning 7940 | Herasil® / Standard | Medium (~200 ppm) | ~220 nm | General purpose; good for 532nm–1064nm |
| JGS3 | — | Infrasil® 301/302 | Low (<10 ppm) | ~250 nm | Reduced 2.73μm OH absorption; IR applications |
Optical Glass — Most Common Grades
CDGM = Chengdu Guangming (成都光明), the primary Chinese optical glass manufacturer. Grades follow GB/T standard.
| Chinese (CDGM) | Schott | Hoya | Ohara | Glass Type | Primary Application |
|---|---|---|---|---|---|
| H-K9L | N-BK7 | — | — | Borosilicate Crown | Most common optical glass; visible & NIR |
| H-UK9L | UBK7 | — | — | UV Borosilicate Crown | N-BK7 grade for UV applications (>330nm) |
| H-F4 | N-F2 | E-F2 | S-TIM2 | Flint | Chromatic aberration correction (doublets) |
| H-ZF3 | N-SF1 | E-FD1 | S-TIH1 | Dense Flint | High refractive index optics |
| H-ZF7L | N-SF6 | FD60 | S-TIH6 | Dense Flint | High refractive index optics |
| H-LaK50 | N-LAK7 | LAC7 | S-LAL7 | Lanthanum Crown | High index, low dispersion imaging lenses |
| H-ZLaF55 | N-LaSF41 | TAFD5 | S-LaH55 | Dense La Flint | Ultra-high refractive index |
| H-QK3L | N-FK5 | FC5 | S-FSL5 | Fluoro Crown | Low refractive index, UV-compatible |
Need a grade not listed here? Contact us