Standard Quality Substrates

The precision optics facility of LAYERTEC produces plane and spherically curved mirror substrates, lenses and prisms of Fused Silica, optical glasses like N-BK7^® and some crystalline materials, e.g. calcium fluoride and YAG. In the following you can find information on the specifications of our standard substrates. Please do not hesitate to contact us also for other sizes, shapes, radii and materials or for special components. For cylindrical, aspherical and free form optics see page Cylinder Optics and Aspheres & Free Forms.

Standard Specifications

Fig.1:Standard specifications of optics

Materials
- Fused Silica: Corning 7980^® or equivalent
- Fused Silica for high power applications in the NIR:
  Suprasil^® 300/3001/3002 / Corning 7979^® or equivalent
- UV Fused Silica (excimer grade): SQ1 E-193^® and SQ1 E-248^®
- IR Fused Silica: Infrasil 302^® or equivalent
- ULE^®
- Zerodur^®
- N-BK7^® or equivalent
- CaF₂: single crystal, randomly oriented, special orientations on request, excimer grade (248 nm and 193 nm) on request
- Sapphire: single crystal, C-cut
- YAG: undoped, single crystal, randomly oriented
- Further information on the substrate materials most frequently used can be found on page Fused Silica

Plane substrates, parallels and wedges
- Standard plane substrates: wedge < 5 arcmin
- Standard parallels: wedge < 1 arcmin or wedge < 10 arcsec
- Standard wedges: wedge = 30 arcmin or wedge = 1 deg

Plano-concave and plano-convex substrates
- Standard radii: 25, 30, 38, 50, 75, 100, 150, 200, 250, 300, 400, 500, 600, 750, 1000, 2000, 3000, 4000, 5000 mm
- Other radii on request

Dimensions
- Fused Silica, ULE^®, Zerodur^®: diameter 3 … 600 mm
- Calcium fluoride, sapphire: diameter 3 … 50.8 mm
- YAG: diameter 3 … 38.1 mm
- Rectangular substrates and other diameters available on request

Tolerances
- Diameter: +0 mm, -0.1 mm
- Thickness: ±0.1 mm
- Clear aperture: central 85 % of dimension
- Chamfer: 0.2 … 0.4 mm at 45°

Table 1:Surface form tolerances (reference wavelength: 546 nm)

Material	Shape	Standard Specification	On Request
Fused Silica	plane spherical	λ/10 λ/10 reg.	λ/30 λ/30 reg. (Ø < 51 mm)
ULE^® and Zerodur^®	plane spherical	λ/10 λ/10 reg.	λ/30 λ/30 reg. (Ø < 51 mm)
N-BK7^®	plane spherical	λ/10 λ/10 reg.	λ/30 λ/30 reg. (Ø < 51 mm)
CaF₂	plane Ø < 26 mm plane Ø < 51 mm spherical	λ/10 λ/4 λ/4 reg.	λ/20 λ/20 λ/20 reg. (Ø < 51 mm)
Sapphire		λ/10	λ/30
YAG	plane spherical	λ/10 λ/8 reg. (typically λ/10 reg.)	λ/30 λ/30 reg. (Ø < 51 mm)
Si	plane spherical	λ/10 λ/8 reg. (typically λ/10 reg.)	λ/20 λ/20 reg. (Ø < 51 mm)

Table 2:Surface imperfection tolerances

Material	Standard Roughness*	Standard Specifications	On Request^*
Fused Silica	< 0.2 nm	5/ 1 × 0.025 L1 × 0.004 Scratch-Dig 10-3	< 0.15 nm	5/ 1 × 0.016 L × 0.0005 Scratch-Dig 5-1
ULE^®	< 0.2 nm	5/ 3 × 0.025 L1 × 0.004 Scratch-Dig 10-5	< 0.2 nm	5/ 1 × 0.016 L1 × 0.0005 Scratch-Dig 5-1
Zerodur^®	< 0.4 nm	5/ 2 × 0.040 L1 × 0.004 Scratch-Dig 10-5	< 0.3 nm	5/ 2 × 0.025 L1 × 0.0010 Scratch-Dig 10-3
N-BK7^®	< 0.3 nm	5/ 1 × 0.040 L1 × 0.004 Scratch-Dig 10-5	< 0.2 nm	5/ 2 × 0.025 L1 × 0.0010 Scratch-Dig 10-3
CaF₂	< 0.3 nm	5/ 1 × 0.04 L5 × 0.006 Scratch-Dig 20-5	< 0.2 nm	5/ 2 × 0.025 L5 × 0.004 Scratch-Dig 10-2
Sapphire	< 0.3 nm	5/ 1 × 0.025 L10 × 0.004 Scratch-Dig 20-3	< 0.2 nm	5/ 1 × 0.016 L1 × 0.0010 Scratch-Dig 10-2
YAG	< 0.2 nm	5/ 1 × 0.025 L2 × 0.004 Scratch-Dig 20-3	< 0.2 nm	5/ 1 × 0.016 L1 × 0.0005 Scratch-Dig 5-1
Si	< 0,3 nm	5/ 3 × 0.025 L10 × 0.004 Scratch-Dig 10-5	< 0,2 nm	5/ 3 × 0.016 L3 × 0.0005 Scratch-Dig 5-1
All specifications according to ISO 10110 (Ø 25 mm). The mentioned Scratch-Dig values are approximately equivalent to MIL-O-13830 which was incorporated into ISO-10110.
* Valid for measurements with optical profilometer taking into account spatial structures in the 1 – 70 µm range.

Please note: Scratches wider than 1 µm are guaranteed not to occur. Specifications according to ISO 10110 are not possible because scratch widths down to 0.3 µm can not be measured as would be required.