Suprasil® 2 Grade A

Heraeus SUPRASIL® 2 Grade A is a high purity synthetic fused silica material manufactured by flame hydrolysis. It combines excellent physical properties with outstanding optical characteristics in the deep UV and the visible wavelength range. The index homogeneity is controlled and specified in one direction (the direction of use or functional direction). In addition, the material provides excellent resistance to damage by high energy UV laser radiation.

All synthetic fused silica SUPRASIL® grades are practically free from bubbles and inclusions.

The optical homogeneity is the main criterion for very low transmitted wavefront distortion.

Suprasil® 2 Grade A ishomogeneous in the primary functional direction. Weak striations, if any, are parallel to the major faces and do not affect the optical performance.
Suprasil® 2 Grade A is the preferred materials for demanding optics in one directional use such as lenses, UV-Laser windows, optical flats, etc.

For general technical data please refer to our data sheet HQS-SO "Quartz Glass for Optics - Data and Properties" 06.2007/V1.0_D

(Bubbles and Inclusions ≤ 0.08 mm diameter are disregarded)

Bubble class:
better than 0 (as per DIN 58927 2/70)

i. e. total bubble cross section within the volume is ≤ 0.03 mm²/100 cm³.

Bubbles according to DIN ISO 10100
1/ 1*0,16 for pieces < 6 kg
1/1*0,25 for pices 6- 30

Inclusions:
None

Spots:
None

Refractive Index
n_C = 1.45637 at 656.3 nm

n_d = 1.45846 at 587.6 nm

n_F = 1.46313 at 486.1 nm

n_g = 1.46669 at 435.8 nm

n = 1.50855 at 248 nm

At 20°C, 1 bar atmospheric pressure

Accuracy: ± 3 x 10^-5

Dispersion
n_F - n_C = 0.00676
v_d = 67,8 ± 0,5

Granular Structure:
None

Striations
In primary functional direction free from striations, i. e. grade A, MIL-G-174-B; weak striations, if any, are parallel to the major faces.

Index Homogeneity
Specified across 90% of diameter or sidelength for machined parts, respectively 80% for raw formed ingots.

In primary functional direction guaranteed total ∆n≤ 5 • 10^-6;

with power subtracted ∆n (p.s.) ≤ 2 x 10^-6;

on special request total ∆n ≤ 1 x 10^-6.

(No special limits on size and weight).

∆n (p.s.) (power subtracted) is calculated by subtracting from a measured ∆n distribution the proportion that gives an exactly spherical aberration of an originally plane optical phasefront. This subtraction procedure is built into most modern interferometer software as an option.

≤ 5 nm/cm across 80% of diameter or side length

≤ 5...15 nm/cm in the rim area.

For typical transmission curves (including Fresnel reflection losses) for a 10 mm path length are shown in the figure please refer to our data sheet "Quartz Glass for Optics - Data and Properties" HQS-SO-DS-06.08


Decadic Extinction Coefficient at 200 nm
k₂₀₀ < 0.005 cm^-1 (typical)
k₂₀₀ < 0.01 cm^-1 (guaranteed)

Using the definition:
Transmittance T = 10^-kd
with d = thickness of sample

Infrared Absorption
OH absorption bands occur at wavelengths around 1.39 µm, 2.2 µm, and 2.72 µm according to an OH content of less than 1000 ppm (weight).

None
With 254 nm excitation (low pressure Hg lamp and Schott UG 5 filter) and visual inspection.

Excellent resistance to damage by high energy UV-laser radiation.

High laser damage threshold.

No degradation of visible transmittance after exposure to Co⁶⁰ γ-radiation (1.15 MeV) with 0.063 Mrad/h for 98 h.