Specifications：
| Materials | Chalcogenide glass | Diameter Range | ~100mm |
| Diameter Tolerance | +0.0/-0.2mm | Thickness Tolerance | +/-0.05mm |
| Surface Quality | 60/40 S/D | Fringes (N) | 3 |
| Irregularity (delta N) | 1 | Centration | 3' |
| Chamfer | 0.1-0.3mmx45 degree | Coatings | AR/AR@3-5µm AR/AR@8-12µm |
Material Properties:
Listed below is a Glass Code Reference Chart of Chalcogenide Glass from the elite manufacturers, identical glass codes are written in the same row. Shalom EO in general would use the IRG20X series chalcogenide materials from Chinese supplier NHG （New Huaguang). Click here to view the properties of the NHG Chalcogenide Glasses IRG Series.
| NHG | VITRON | PIKE | UMICORE | SCHOTT |
| IRG201 | IG2 | AMTIR-1 | IRG22 | |
| IRG202 | GASIR-1 | |||
| IRG203 | GASIR-2 | |||
| IRG204 | IG2 | AMTIR-1 | IRG22 | |
| IRG205 | IG5 | AMTIR-3 | IRG25 | |
| IRG206 | IG6 | AMTIR-2 | GASIR-5 | IRG26 |
| IRG207 | IG4 | IRG24 |
Chalcogenide glass lenses are lenses made of chalcogenide glass, which are glass material composed of chalcogen elements (S, Se, Te) combined with other elements such as As, Sb, or Ge. Chalcogenide glass features a broad IR transmission wavelength range in the MWIR/LWIR region (3-5 micro,8-12 micro) with a superior transmission rate within the range. The thermal properties of Chalcogenide glass lenses are also remarkable, with low temperature coefficients of refractive index, Chalcogenide glass lenses are attractive candidates for producing passive optical athermalized IR lens assemblies of compact and lightweight design. Furthermore, Chalcogenide glass has a lower softening point and mechanical hardness than common crystal materials, therefore could be processed into various optical components with higher efficiencies. The production cost of chalcogenide glass is lower than most IR crystal materials (1/4 of that of Germanium). It is also feasible, using high precision molding, to realize bulk production of aspheric Chalcogenide glass lenses. With China’s export controls on Ge, the chalcogenide glass lens has emerged as a potential alternative to Ge lens.
Hangzhou Shalom EO offers Custom Chalcogenide Glass Lenses and Chalcogenide Glass Ball Lenses with a maximum diameter of 100mm and anti-reflection coatings at LWIR and MWIR regions. The lens forms (ball lens, aspheric lens, convex lens, concave lens, etc.), dimensions, and other parameters could all be tailored for you. Various Chalcogenide Glass Materials could be selected upon your request, the majority being the Chinese IRG series from NHG, the glass codes including IRG201, IRG202, IRG203, IRG204, IRG205, IRG206, and IRG207, while other similar glass codes from other companies could also be procured.
Shalom EO is now capable of coating DLC (Dimond Like Carbon) coating and HD (High Durability) coating on Chalcogenide glass.
DLC coatings, full name diamond-like carbon coatings, in the context of infrared optics, refer to coatings made of amorphous carbon thin films with abundant sp3 bond structure. The properties of the coating are similar to diamond, hence the name. In IR optics, chalcogenide is emerging as a substitute for single-crystal germanium because of lower cost and lighter weight, and similar infrared optical performance to that of Ge.
Why does chalcogenide glass need DLC coatings? The weakness of chalcogenide is that it is soft, susceptible to scratches, and not very corrosion-resistant. By adding DLC coatings onto the chalcogenide glass substrate, the optics is strengthened and can withstand harsh outdoor environments.
What are the major technical difficulties of coating DLC onto the chalcogenide glass substrates?
1. Mismatched coefficients of thermal expansion – the significant difference in thermal expansion between chalcogenide glass and DLC film makes alternating heating and cooling prone to causing film cracking;
2. High internal stress in the film – DLC film has high internal stress, which, if not properly controlled, can easily lead to surface deformation or even substrate breakage;
3. Difficulty in achieving both hardness and transmittance – achieving a balance between high hardness and wear resistance, and high transmittance for image preservation, is extremely challenging;
In addition, the characteristics of chalcogenide materials are that, due to their poor film-substrate adhesion, the surface of chalcogenide glass is chemically inert and the substrate is easily oxidized, which leads to the film layer being prone to peeling and flaking.
That’s why most of the manufacturers remain in the stage of research and development, but fail to realize large volume production of DLC-coated chalcogenide glass infrared optics.
HD coatings on chalcogenide glass:
HD coatings, in the terminology of IR optics means high durability coatings. HD coatings only describe the performance of the coatings is hard and durable, but do not specify a certain coating materials. HD coatings oftentimes contains DLC structure.
Shalom EO has overcome the technical challenges of coating diamond-like carbon coatings and HD coatings on infrared lenses made of chalcogenide glass. The DLC-coated chalcogenide glass lenses feature outstanding scratch-resistance, salt-spray resistance, and high infrared transparency. The products are capable of enduring various application scenarios like exposure to sand/acid/heat, etc.
