fused silica witness sample Barr Associates AR coating

Product Description

Prestigious US Defense Lab AR-Coated 1 inch diameter x 1.3 mm thick (plano-plano flat disk) Fused Silica Witness Sample – From US Defense Space Optics Project

This is a rare surplus witness sample from a Prestigious US Defense Lab, a premier U.S. Department of Defense research center specializing in advanced electro-optical systems for space surveillance, missile defense, and intelligence applications. Labeled as “L5, WFOV WITNESS SAMPLE,” this item was produced by Barr Associates (now Materion Barr Precision Optics & Thin Film Coatings) , a world leader in high-performance thin-film coatings for aerospace and defense .

Witness samples like this are coated alongside actual flight hardware to verify coating quality, thickness, uniformity, and performance through non-destructive testing—ensuring the primary optics meet stringent space-qualified standards without risk . These samples directly tie to DoD space-based optical telescopes and instruments, such as those used in the Space Surveillance Telescope (SST) program or similar systems like the Space-Based Infrared System (SBIRS) for missile early warning and Overhead Persistent Infrared (OPIR) sensing . The WFOV (Wide Field of View) design supports wide-area scanning for detecting faint satellites, space debris, or missile launches. Owning one connects you to cutting-edge U.S. defense technology, making it ideal for collectors, researchers, or engineers working on optics prototypes.

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Key Specifications

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Substrate & Coating Advantages

High-Purity Fused Silica (SiO₂) :

• Exceptional thermal stability with ultra-low coefficient of thermal expansion (0.55 x 10⁻⁶/°C)

• High purity (>99.9%) minimizes absorption and scatter

• Excellent transmission from UV through short-wave infrared (0.2–3.5 μm)

• Resists environmental degradation, radiation, and thermal cycling—space-flight certified

• Superior mechanical strength and chemical durability

Broadband Anti-Reflective (AR) Dielectric Multilayer Coating :

• Applied to both sides for optimal performance

• Multi-layer dielectric stack (e.g., SiO₂, Ta₂O₅) via precision deposition

• <1% reflectivity per surface in visible to near-infrared range

• 99% total transmission, minimizing ghosting and stray light

• Durable, hard coating resistant to cleaning and environmental exposure

Barr Associates / Materion Heritage :

• Founded in 1971 by Edgar Barr, a pioneer in thin film filters

• World leader in precision thin film coatings for defense, aerospace, space, astronomy, and scientific applications

• ISO 9001:2008 certified facilities with advanced deposition technologies including IBS, IAD, magnetron sputtering

• Upgraded facility supports coating of optics up to 1.4 meters for space and astronomy programs

• Materion provides beryllium mirrors for the James Webb Space Telescope

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Space & Defense Program Connections

This witness sample directly relates to U.S. defense space-based optical systems:

The “WFOV” designation connects directly to the wide-area scanning requirements of these systems, which demand exceptional optical performance across large fields of view.

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Applications & Uses

Optical Research & Prototyping:

• Perfect as a low-cost AR-coated window, filter substrate, or test optic in lab setups

• Ideal for lasers (e.g., HeNe, diode), spectrometers, interferometers, or imaging systems

• Reduces ghosting, stray light, and losses in visible/NIR experiments

Astronomy & Telescope Builds:

• Integrate into DIY wide-field telescopes, CCD cameras, or educational models simulating space surveillance systems

• Enhances light gathering for stargazing, astrophotography, or debris tracking demonstrations

• Can serve as a protective window for sensors or corrector plate in custom designs

Defense & Aerospace Simulations:

• Prototyping EO/IR sensors, LIDAR, or free-space optical communications

• Mimicking DoD hardware for non-classified R&D and technology demonstrations

• Testing optical concepts relevant to missile warning and space situational awareness

Educational & Display Purposes:

• Demonstrate thin-film optics, interference effects, or AR principles in classrooms, museums, or personal collections

• Its Prestigious US Defense Lab/DoD provenance adds historical value for optics enthusiasts or space tech collectors

• Hands-on education in advanced optical engineering and space-qualified manufacturing

Industrial Testing:

• Use in environmental chambers for durability tests (e.g., salt fog, temperature, polarization)

• Reference standard for coating verification in manufacturing

• Witness sample for tracking deposition uniformity across coating runs

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What Are Witness Samples?

Witness samples are small optical flats coated simultaneously with flight hardware to:

• Verify coating quality without touching primary optics

• Measure thickness and uniformity via spectrophotometry

• Test environmental durability (humidity, adhesion, abrasion)

• Validate spectral performance before flight integration

• Archive coating runs for traceability and quality assurance

This practice is standard in defense and aerospace programs, where primary optics are too valuable to risk for testing .

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Condition & Packaging

⚠ HANDLING NOTE: This is a precision optical component with delicate AR coatings. Handle only by edges with clean gloves. Never touch coated surfaces. Store in clean, dry environment when not in use.