BK7 B270 Superwhite Borofloat Fused Silica Soda Lime Float Glass

Bk7, UV Grade, IR Grade & Optical Glass

Properties of Optical Glass

Click on a material above or choose a Schott or Ohara part number, to see the spectral and the material properties. Here are the general characteristics:

  • Fused Silica is the purest form of SiO2. This glass has superior transmission in both the UV and IR spectra, a very low dielectric coefficient and excellent properties where flourescence or solarization are an issue. Unlike sapphire (a crystalline structure, not amorphous) fused silica can be shaped to many forms and sizes. It has excellent resistance to non-fluorinated acids, solvents and plasmas. Heraeus and Nikon both produce extremely high grade (pure) Fused Silica glasses that exhibit excellent ultraviolet and infrared performance. Where purity, a non-reactive, durable substrate and homogeneity between melts (uniform optical properties) are needed, this high quality material is the likely choice.
  • Bk7 is a barium borosilicate glass known for its high transmission and clean, clear appearance. It is by far the most common material for many optical glass applications, because it offers good optical properties and a reasonable price. It's used often as a standard of comparison for other glass materials.
  • Borofloat® is a particular Schott Borosilicate Glass. It is characterized by excellent flatness and better resistance to heat. These characteristics make Borofloat more costly than float glass, but borosilicates retain shape and handle thermal shock better than other, less expensive glasses.
  • B270 or Crown Glass or 'water white' has good optical transmission, and appears crystal clear as a result of fewer impurities. It can be polished and readily accepts all types of coatings.
  • GE 124 & NSG OZ are Fused Quartz glasses. Fused quartz is used in applications where good ultraviolet light transmission, very good thermal stability and chemical inertness (resistance to stains) are required. Fused Quartz is harder and more difficult to polish than borosilicate, so the cost is higher. For applications where prolonged or periodic temperatures are more extreme or there is a need for higher purity, fused quartz is an appropriate choice.
  • Soda Lime, also called 'Float Glass' is a common, inexpensive substrate. The oldest glass, float glass can appear with a slight greenish or blue tint, depending upon the amount of iron and other elements. It is easily tempered to increase strength.

'Laser Grade' & Custom Products (Upon Quote)

Should you wish different specifications than those specified on the right hand side of this page for Commercial or Technical Grade materials, please click on Custom Request.


For our "Quick Turn" items, VPG reserves the right to substitute optical glass substrate materials sourced from different manufacturers, as long as the material properties, optical properties and quality of manufacture meet or exceed the specifications of the customer's order. If you require a specific manufacturer's part number, or should you require certification of the materials used, we will be pleased to do it, but you must request a Custom Request.