Blank Materials for Infrared Optics
EOM offers two distinct yet both highly suitable materials for infrared optics. We provide high-purity Germanium blanks as well as blanks made out of GASIR®, a chalcogenide glass with a much wider spectral range than Germanium as well as a dn/dt that is 8 times as low.
Umicore's GASIR® chalcogenide glass is an ideal material for both high-performance infrared imaging systems and high-volume commercial applications. GASIR® has a dn/dt 8 times lower than germanium and a much wider spectral range covering NIR, MWIR and LWIR. GASIR® can be finished with traditional manufacturing technologies as well as moulding.
Coated GASIR®1 has a wider transmission spectrum than germanium, and GASIR® blanks are less costly and more stably priced than germanium blanks.
GASIR® - optics for new and existing applications
A unique molding process allows the manufacture of finished, spherical, aspherical and diffractive lens geometry in medium to large volume production runs with a competitive price-performance ratio. For low to medium volume needs GASIR® can be manufactured with polishing or diamond turning.
Compared with germanium, the traditional infrared material, GASIR® offers a wider transmission spectrum and much better possibilities to athermalize optics.
Umicore offers GASIR® both as blank material, lens or in off-the-shelf infrared lenses.
GASIR®'s key advantages are:
- More stable pricing than germanium with the possibility for long term fix pricing
- Wider spectral range than germanium. GASIR® is transparent from 0.8 µm up to 16 µm
- 8 times lower change of refractive index with temperature than germanium, allowing simple athermalized design
- Moulding process allowing for high volume, cost effective optics
Potential application fields for GASIR® include:
- Automotive night vision and sensing
- Security and surveillance
- Thermography and predictive maintenance
- Fire fighting
- Smart sensing
Germanium is the preferred lens and window material for high performance infrared imaging systems in the 8-12 µm wavelength band. Its high refractive index makes Germanium ideal for low power imaging systems because of minimum surface curvature. Chromatic aberration is small, eliminating the need for correction.
Over more than thirty years Umicore has developed an unmatched expertise in the Czochralski pulling of high quality germanium single crystals. Diameters up to 350 mm are available in different resistivity ranges, with a homogeneity of refractive index up to 10-5 and an absorption coefficient less than 0.02 cm-1 in the 8-11 µm band. Our ready-to-polish shaping of lens blanks, contoured window blanks, and special shapes, meet the customers' most stringent requirements.