75mm BK7 λ/10 optical window

Product Description

Precision 75mm BK7 Plano-Plano Optical Window – λ/10 Flatness, 10mm Thick (Uncoated)

This is a high-precision, uncoated optical window fabricated from BK7 crown glass, with its flatness and material clearly marked on the edge: “BK7” and “1/10” (indicating λ/10 flatness). With a 75mm diameter and 10mm thickness, it offers excellent parallelism and stability, making it an ideal reference flat, broadband beam path window, or substrate for custom optical work.

Key Specifications:

• Diameter: 75 mm (~3 inches)

• Thickness: 10 mm (excellent parallelism)

• Material: BK7 crown glass (high clarity, >90% transmission from 350 nm to 2.0 µm)

• Flatness: λ/10 (marked “1/10” – suitable for precision reference applications)

• Coating: Uncoated polished (maximizes broadband transmission; ~4% reflection per surface)

• Clear Aperture: >98% of diameter (see Condition note)

• Edge Markings: “BK7” (material) and “1/10” (flatness) for clear identification

Condition:

✅ EXCELLENT SURPLUS – Optical surfaces are pristine, with no scratches or digs in the clear aperture
📍 NOTE: Contains one small edge nick outside the central 98% clear aperture – does not affect optical performance

Why This Window Is a Standout Value:

• Certified Flatness: The etched “1/10” marking provides immediate verification of λ/10 flatness—a trusted specification for reference and testing applications.

• Broadband Utility: Uncoated surfaces ensure maximum transmission across the visible to near-IR spectrum without coating-induced limitations.

• Professional Markings: Clear material and flatness identification streamline integration and documentation in lab settings.

Applications:

• Precision Reference Flat: For optical testing, interferometry, autocollimation, or alignment.

• Broadband Beam Path Window: Ideal for visible to near-IR laser systems where coating damage or spectral restrictions are a concern.

• Optical Spacing/Substrate: Use as a stable spacer or base for applying custom AR, HR, or filter coatings.

• Educational & Experimental Optics: Perfect for university labs, optical workshops, or hobbyist projects requiring a known-flat, broadband component.

Note:

As an uncoated optic, each surface reflects approximately 4% of incident light. For applications requiring reduced reflections, an AR coating can be applied; for maximum bandwidth and damage threshold, the uncoated design is optimal.