50mm N-BK7 plano-convex lens 800mm focal length BBAR

Product Description

Research Lab Surplus – Precision N-BK7 Plano-Convex Lens, 50mm Diameter, 800mm EFL, Visible Broadband AR Coated

A high-quality plano-convex lens sourced directly from a research laboratory clearout, featuring premium visible broadband anti-reflection (BBAR) coating and precision N-BK7 substrate. With a 50mm clear aperture and 800mm effective focal length (EFL) , this lens delivers low-aberration, high-transmission performance ideal for beam collimation, gentle focusing, and experimental optical systems.

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🔍 Key Specifications:

• Material: N-BK7 optical glass – borosilicate crown, excellent homogeneity

• Diameter: 50 mm

• Effective Focal Length (EFL): 800 mm (f/16 focal ratio)

• Edge Thickness: ~4 mm (lightweight profile)

• Design: Plano-convex – one flat surface, one gently curved convex surface

• Coating: Multi-layer broadband AR (BBAR) for visible spectrum – <1% reflectivity per surface, >99% transmission

• Coating Range: 400–700 nm optimized

• Condition: Excellent – clean surfaces, no scratches or chips

• Equivalent Models: OptoSigma SLB-50-800PM, Thorlabs LA1908-A, Edmund Optics #32-334

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✅ Condition & Notes:

• Condition: Excellent – Research Lab Surplus

• Origin: Direct from university or government research laboratory decommission

• Optical Surfaces: Clean, no coating defects, haze, or cleaning marks

• Edge: Precision-ground, ready for standard 50mm lens cells

• Includes: Lens only – no mounting hardware or original packaging

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⚙️ Why This Lens is Exceptional:

🔬 Genuine Research-Grade Pedigree:
This is not commercial overstock or consumer-grade optics—it is laboratory-surplus hardware from active research environments. These lenses were selected, inspected, and used by professional scientists and engineers for demanding experimental work.

💎 Premium BBAR Coating:
Unlike economy single-layer MgF₂ coatings, this multi-layer broadband AR coating delivers:

• <1% reflectivity across entire visible spectrum (400–700 nm)

• >99% transmission – maximizes throughput in photon-starved systems

• Durable hard coating – resistant to cleaning and environmental exposure

📏 Long Focal Length Advantage:
The 800 mm EFL at f/16 provides:

• Minimal spherical aberration – near-diffraction-limited on-axis performance

• Gentle focusing power – ideal for collimation over extended working distances

• Forgiving alignment tolerances – perfect for educational and prototyping applications

🪶 Lightweight Profile:
At only 4 mm edge thickness, this lens is easy to mount and places minimal stress on lens cells and translation stages.

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🛠️ Applications & Uses:

💫 Beam Collimation & Expansion:

• Collimate divergent sources (laser diodes, SLEDs, fiber outputs) with minimal wavefront error

• Beam expander output lens – low divergence over long paths

• Alignment telescope objective – precision autocollimation and targeting

🔭 DIY Telescope & Optics:

• Objective lens for low-power, wide-field refractor telescopes

• Finder scope or guide scope objective

• Galilean beam expander ocular component

🔬 Laboratory & Experimental:

• Focusing lens for optical bench setups

• Relay lens in multi-element imaging trains

• Field lens for pupil relay systems

• Spatial filter output collimator

🎯 Laser Alignment & Beam Steering:

• Visible laser beam control (HeNe, 532 nm, 635 nm, 405 nm)

• Long working-distance focusing for alignment tasks

• Beam routing in prototype optical systems

🧪 Educational Demonstrations:

• Measure focal length with nodal slide or conjugate methods

• Demonstrate spherical aberration vs. aperture

• Compare AR-coated vs. uncoated transmission

📷 Projection & Imaging:

• Low-power magnifier for inspection tasks

• Projection lens in custom enlargers or solar projectors

• Condenser system component