2 inch λ/10 fused silica optical flats AR-coated set of 3

Product Description

Premium Trio of 2″ Diameter λ/10 Fused Silica Dual-Surface Optical Flats with Anti-Reflection Coating – Excellent Condition

A rare, matched collection of three precision 2″ (50.8mm) fused silica optical flats, each polished to λ/10 surface flatness or better and featuring broadband anti-reflection (AR) coatings on both reference surfaces. Sourced from professional laboratory surplus, these dual-surface reference flats represent the gold standard for interferometric flatness testing—essential metrology tools for any serious optics, manufacturing, or research facility.

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🔍 Key Specifications (All Three Flats):

📐 Dimensions & Material:

• Diameter: 2.0″ (50.8 mm) – standard mounting compatibility

• Thickness: 9 mm – exceptional rigidity, minimizes gravitational sag

• Material: Fused silica – UV-grade, near-zero thermal expansion (0.55 × 10⁻⁶/°C)

• Transmission Range: Deep UV to near-IR (200 nm – 2.5 µm)

💎 Surface & Coating:

• Flatness: λ/10 or better at 633 nm (marked/verified)

• Surfaces: Dual-side high-precision polish – both faces reference-quality

• Reference Surface Indication: Pointer arrow engraved on edge – unambiguous orientation

• Coating: Broadband AR (visible spectrum optimized) – <0.5% reflectivity per surface

• Edge Finish: Safely ground/frosted – no sharp edges, comfortable handling

✅ Overall Condition:

• All three flats: Excellent surplus condition

• Optical Surfaces: No scratches, chips, or coating defects on primary reference surfaces

• Usage History: Very lightly used if at all – professional laboratory environment

• Includes: Flats only – no storage cases or certification documents

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📦 Individual Flat Details:

1. Modern Beveled λ/10 Flat

• Markings: “Q 10” engraved; reference surface arrow

• Edge Finish: 45° chamfers on both edges – modern precision fabrication

• Condition: Cleanest of the three – looks almost new

• Cosmetic: Excellent – no visible wear, haze, or handling marks

• Best For: Primary reference standard, ISO-compliant metrology, demonstration-quality appearance

2. Classic Marked λ/10 Flat

• Markings: Engraved “λ/10” + pointer arrow indicating reference surface

• Edge Finish: Sharp ground edges – traditional precision fabrication

• Condition: Very clean surfaces – identical material and performance to modern flat

• Cosmetic: Older-style edge finish, optically pristine

• Best For: Traditional metrology lab, unambiguous reference identification, heritage equipment

3. Classic Unmarked λ/10-Quality Flat

• Markings: No surface engraving – λ/10 quality verified by provenance and inspection

• Edge Finish: Sharp ground edges (traditional fabrication)

• Condition: One surface has very light storage haze; opposite surface is pristine

• Note: Haze is cosmetic only – does not affect flatness, fringe contrast, or metrology function

• Best For: Secondary reference, educational use, non-critical testing, exceptional value

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💎 Why These Flats Are Exceptional:

🔬 Fused Silica – The Premium Choice for Reference Optics:
Unlike BK7 or standard optical glass, fused silica offers:

• Near-zero thermal expansion – 5× better than BK7, no focus drift with temperature

• Deep UV transmission – usable down to 200 nm for excimer and UV interferometry

• Superior homogeneity – no striae, bubbles, or refractive index variations

• Laser damage resistance – suitable for high-power metrology applications

• Chemical durability – resists humidity and environmental degradation

💎 λ/10 Flatness – Genuine Laboratory Grade:
λ/10 at 633 nm (≈63 nm peak-to-valley) is the de facto standard for precision metrology:

• Quantifiable accuracy – measure test surfaces to 0.1 fringe resolution

• ISO 10110 compliant – suitable for certified QC applications

• Interferometer-ready – immediate use in Fizeau, Twyman-Green, and Michelson setups

• Traceable capability – can be certified against NIST-traceable standards

🎯 AR-Coated Both Sides – Rare & Valuable:
Most surplus optical flats are uncoated (4% reflection per surface). These flats feature:

• Broadband AR coating on both reference surfaces – <0.5% reflectivity

• Eliminates ghost fringes from back-surface reflections

• Maximizes fringe contrast – cleaner, higher-SNR interferograms

• Laser-compatible – no parasitic etalon effects in coherent illumination

• Transmission-optimized – ideal for Fizeau interferometry

🔄 Dual-Surface Usability:
Both sides are polished to λ/10 reference quality:

• Two working surfaces per flat – extended service life, redundancy

• Self-verifying – verify one surface against the other

• Cost efficiency – essentially two reference flats in one optic

• Wear distribution – rotate usage between surfaces

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🛠️ Applications & Uses:

🔬 Interferometric Flatness Testing:

• Verify surface figure of lenses, mirrors, prisms, and optical windows

• Fizeau interferometry – transmission flat reference

• Newton’s ring testing – contact or near-contact fringe analysis

• Optical contacting – temporary bonding for assembly and alignment

📏 Precision Metrology & Quality Control:

• Gauge block calibration – wringing surface verification

• Mechanical seal flatness – semiconductor, vacuum, hydraulic, and aerospace systems

• Optical manufacturing QC – incoming inspection, process control, final certification

• ISO/AS9100 compliance – documented traceable reference capability

🔭 Research & Development:

• Laser cavity alignment – verify mirror and window flatness

• High-power laser optics – certify debris shields, harmonic separators, and dichroics

• Space/defense optics – qualification testing under thermal vacuum

• University metrology labs – graduate student training in interferometry

🧪 Educational & Training:

• Demonstrate interference phenomena – coherent vs. incoherent sources

• Teach fringe interpretation – P-V, RMS, power, irregularity

• Optical fabrication courses – verify student-polished test plates

• Physics demonstrations – wavelength measurement, optical path difference

🏭 Industrial & Semiconductor:

• Wafer flatness verification – semiconductor substrate inspection

• Precision machining QC – surface plates, machine tables, sealing surfaces

• Optical assembly – verify adhesive bond lines, mounting-induced distortion