Precision N-BK7 Optical Window – 75 mm Diameter

Premium surplus plano-parallel optical window in pristine, cleaned condition – ready for immediate use. Precision fabricated from N-BK7 optical glass with these specifications:

• Diameter: 75 mm

• Thickness: 12.5 mm

• Material: N-BK7 (borosilicate crown glass)

• Surfaces: Both sides high-precision polished, flat, and parallel (plano-plano configuration)

• Coating: Uncoated – natural ~4% reflection per surface

• Edges: Finely ground and beveled with arrow mark (manufacturing reference)

• Condition: Excellent surplus/new-old-stock – surfaces professionally cleaned, no scratches, chips, haze, or defects; optically clear with high transmission (~92%)

This thick, robust window offers mechanical strength and optical clarity, perfect for:

• Protective viewports in instruments or laser enclosures

• Beam path windows in imaging, spectroscopy, or prototyping setups

• Custom coating substrate (ideal base for AR, mirror, or filter coatings)

• Vacuum/pressure separation or general optical experimentation