Infrasil® 302

INFRASIL® 302 is an optical quartz glass grade manufactured by fusion of natural quartz crystals in an electrically heated furnace. It combines excellent physical properties with outstanding optical characteristics especially in the IR and the visible wavelength range. The index homogeneity is controlled and specified in one direction (the direction of use or functional direction).
All INFRASIL® grades show a low bubble and inclusion content. The optical homogeneity is the main criterion for very low transmitted wavefront distortion.

INFRASIL® 302 is homogeneous in the primary functional direction. Weak striations, if any, are parallel to the major faces and do not affect the optical performance. INFRASIL® 302 is the preferred material for demanding optics in one directional use such as lenses, IR-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 (as per DIN 58927 2/70)
INFRASIL 302 : 0.....1

Bubbles according to DIN ISO 10100
1/ 1*0,2 for pieces < 6 kg
1/1*0,5 for pieces 6-30 kg

Inclusions:
None

Spots:
None

Refractive Index
n_C = 1.45646 at 656.3 nm

n_d = 1.45856 at 587.6 nm

n_F = 1.46324 at 486.1 nm

n_g = 1.46681 at 435.8 nm

At 20°C, 1 bar atmospheric pressure

Accuracy: ± 3 x 10-5

Dispersion
n_F - n_C = 0.00678
v_d = 67.6 ± 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≤ 6 x 10^-6;
with power subtracted ∆n (p.s.) ≤ 4 x 10^-6;

on special request total ∆n ≤ 3 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) please refer to our data sheet "Quartz Glass for Optics - Data and Properties" HQS-SO-DS-06.08 path length are shown in the figure.

Infrared Absorption
Very weak absorption bands occur at wavelengths around 1.39 µm, 2.2 µm, and 2.72 µm according to an OH content of ≤ 8 ppm (weight).

Blue-violet with 254 nm excitation (low pressure Hg lamp and Schott UG 5 filter) and visual inspection.

Good, visible transmittance is not degraded significantly by ionizing radiation.