This option upgrades the neutral density filter's substrate from glass to fused silica such that it supports UV Light from 250nm and upwards. Without this upgrade, the glass substrate neutral density filter only supports wavelengths ≥350nm. Please note that this option is recommended for UV-A and UV-B light applications, but is not required for solar cell testing applications since the ASTM and IEC standards for solar cell testing only require the spectrum from 350-1100nm which is well supported by the standard glass substrate neutral density filter.
 
Tolerance Range
Please note the tolerance range is worse with the fused silica substrate than glass substrate. Tolerance values are posted in the technical specifications section below.
 
Technical Specifications

• Uniformly reflects UV (±5%) 250-350nm, Visible (±2%) 350-800nm and NIR light (±5%) 800-2000nm
• Metallic Coating to reflect unwanted light back to source rather than absorbing it
• Fused Silica substrate limits spectral region 250-2000nm.
• Rated at 100°C (glass and fused silica)
• Bevelled edge means clear aperture is only 68.6 x 68.6mm instead of 76.2 x 76.2mm
• Designed for 0° operating angle