| Material | Refractive Index (at 2 µm) | Properties | |
| AgBr | 22,000-286 | 2.30 | A soft crystal; insoluble in water; darkens upon exposure to UV radiation; will cold flow. |
| AgCl | 10,000-360 | 2.07 | Soft crystal that is insoluble in water; darkens upon exposure to UV radiation; will cold flow. |
| Al2O3 (Sapphire) | 50,000-1,650 | Glass-like | |
| BaF2 | 67,000-740 | 1.46 | A hard, brittle crystal; insoluble in water; good resistance to fluorine and fluorides; no fog. |
| CaF2 | 77,000-1,110 | 1.42 | A strong crystal; resists most acids and alkalis; withstands high pressure; insoluble in water; no fog. |
| CdTe | 10,000-400 | 2.4 | Lower thermal conductity than ZnSe (used with CO2 lasers). |
| CsI | 40,000-200 | 1.74 | Soft crystal; soluble in water; hydroscopic; offers an extended transmission range. |
| GaAs | 7,000-650 | 3.33 | Hard crystal, can be made amorphous |
| Ge | 5,500-600 | 4.00 | A hard, brittle crystal; insoluble in water; well suited for ATR. |
| Irtran-2 | 17,000-720 | 2.26 | Insoluble in water; withstands thermal and mechanical shocks; avoid strong oxidizers; fringes induced due to high refractive index. |
| KBr | 40,000-400 | 1.53 | Very soft, water soluble crystal; low cost and good transmission range; fogs. |
| KRS-5 | 20,000-250 | 2.37 | A soft crystal, deforms under pressure; good ATR material. |
| LiF | 50,000-1,700 | 1.4 | Best VUV transmitter available |
| MgF2 | 75,000-1,250 | ||
| NaCl | 40,000-625 | 1.52 | Very soft, water soluble crystal; low cost and good transmission range; fogs. |
| Si | 83,300-660 300-0 (depends on doping) | 3.40 | A hard and brittle crystal; inert; ideal material for far-IR. |
| SiO2 (Quartz) | 65,000-2,700 | A hard crystal, clear in the visible | |
| ZnS (Cleartran) |
23,800-833 | A water-free form of ZnS | |
| ZnSe | 20,000-454 | 2.40 | A hard and brittle crystal; inert; ideal material for ATR. |