-   Material: N-BK7

High precision surface:

        - DURAN 50: dilatation 3.2x10⁻⁶/°C

        - ZERODUR: dilatation 0 ± 0.15x10⁻⁶/°C

-   Dimensional Tolerance:

        - Dimension:
                - 0 to 50mm: +0  -0.1mm
                - 60 to 120mm: +0  -0.2mm
                - 150 to 250mm: +0  -0.3mm

        - Thickness: ± 0.2mm

* In this chart, thickness is given by the 7th and 8th of the reference (in mm)

On request: other dimensions to 1000 mm

Coating:

        - Protected aluminium: R average > 90% visible and U.V.
        - Protected silver: R moyen > 97% visible and I.R.
        - Protected gold: R average > 98.5% I.R.
 
        - Dielectric:

                - R max>99.5%, one specific wavelength.
                - R max>98% some bandwidth