20mm Dia., 1mm Thick, NIR II Coated λ/4 N-BK7 Window

Product Details Circular and Rectangular Sizes from 2mm to 200mm 8 Broadband Anti-Reflection Coating Options Available World’s Largest Selection of Standard N-BK7 Windows Also Available with Ultra-Thin N-BK7 Windows TECHSPEC λ/4 N-BK7 Precision Windows are ideally suited for industrial and low-power laser applications. The high tolerance design yields minimal beam distortion and scatter. Broadband coating options extend the range of these precision windows through the visible and near-infrared spectra. TECHSPEC λ/4 N-BK7 Precision Windows are offered in circular and rectangular sizes ranging from 2mm to 200mm. Note: New additions to this product family may be specified with a transmitted wavefront distortion (TWD) specification instead of a surface flatness. For more information on the difference between these two specifications, see our application note on Understanding Optical Windows . Specifications General Type: Protective Window Type of Window: Glass Physical & Mechanical Properties Clear Aperture CA (mm): 18.00 Diameter (mm): 20.00 +0.00/-0.25 Thickness (mm): 1.00 ±0.20 Parallelism (arcmin): <1 Bevel: Protective as needed Clear Aperture (%): 90 Edges: Fine Ground Poisson's Ratio: 0.21 Young's Modulus (GPa): 82 Knoop Hardness (kg/mm 2 ): 610.00 Optical Properties Coating: NIR II (750-1550nm) Substrate: Many glass manufacturers offer the same material characteristics under different trade names. Learn More N-BK7 Index of Refraction (n d ): 1.516 Surface Quality: 60-40 Transmitted Wavefront, P-V: λ/4 Abbe Number (v d ): 64.17 Coating Specification: R abs ≤1.5% @ 750 - 800nm R abs ≤1.0% @ 800 - 1550nm R avg ≤0.7% @ 750 - 1550nm Wavelength Range (nm): 750 - 1550 Damage Threshold, By Design: Damage threshold for optical components varies by substrate material and coating. Click here to learn more about this specification. 8 J/cm 2 @ 1064nm, 10ns Material Properties Density (g/cm 3 ): 2.51 Coefficient of Thermal Expansion CTE (10 -6 /°C): 7.1 (-30 to +70 °C) 8.3 (+20 to +300 °C) Regulatory Compliance RoHS 2015: Compliant × Certificate of Conformance: View × Reach 253: Compliant ×