Bi-Concave Lenses

Name: Bi-Concave Lenses
Brand: PhotonEdge
SKU: PE-LENS-BCV-004
Availability: LimitedAvailability

Key Specifications

Material	N-BK7 (K9)
Diameter	5-75 mm
Focal Length	-5 to -500 mm
Wavelength	350-2000 nm
Surface Quality	40-20 / 20-10
Flatness	λ/4 @ 632.8nm
Symmetry	Equal R on both surfaces
Coatings	AR coatings available

What Is a Bi-Concave Lenses?

Bi-concave (double concave) lenses have two concave surfaces with equal radii. This symmetric negative lens provides uniform beam divergence regardless of orientation, simplifying alignment in optical systems.

They are used in beam expansion, as diverging elements in compound optical systems, and in applications where orientation-independent performance is beneficial.

When Should You Use This Product?

✔ Good Choice When

✓ Symmetric beam divergence regardless of orientation
✓ Diverging elements in compound optical systems
✓ Laser beam expansion (paired with positive lenses)
✓ Applications where orientation independence simplifies assembly

⚠ Consider an Alternative When

✗ Collimated-to-focused needed → Plano-Convex Lens

✗ Minimum spherical aberration divergence → Plano-Concave Lens

✗ Chromatic correction needed → Achromatic Doublet (negative)

✗ UV wavelengths → UV Fused Silica Bi-Concave

Available Optical Materials

Select the optimal substrate material based on your wavelength, environment, and budget requirements.

Material	Transmission	Key Advantage	Considerations
N-BK7	VIS / NIR (350-2000nm)	General-purpose, low cost, good homogeneity	Not suitable for UV < 350nm
UV Fused Silica	UV / VIS / NIR (185-2100nm)	Excellent UV transmission, low absorption, high LIDT	Higher cost than BK7
CaF₂	Deep UV / VIS / IR (130-7800nm)	Broadest transmission range, low refractive index	Fragile, higher cost
Sapphire	UV / VIS / NIR (150-5500nm)	Extremely hard (9H), scratch resistant	Birefringent, higher refractive index

Not sure which material to choose?

Ask AI Optical Engineer

Optical Coating Options

AR 350-650nm

Broadband AR for visible range. R < 0.5% per surface.

Typical use: General visible laser and imaging

AR 650-950nm

AR for NIR range (780nm, 808nm, 850nm diodes).

Typical use: NIR laser diode collimation and fiber coupling

AR 950-1250nm

AR for 1064nm and nearby wavelengths.

Typical use: Nd:YAG and fiber laser systems

BBAR

Low reflection across 400-1000nm broadband.

Typical use: Multispectral applications

Uncoated

Raw glass surface. ~4% reflection per surface.

Typical use: Non-critical applications

How to Specify Your Coating

To select the right coating, please provide: (1) Operating wavelength, (2) Angle of incidence, (3) Required transmission or reflectivity, (4) Laser power density (if applicable), (5) Operating environment.

Engineering Considerations

Key factors to evaluate when specifying this optical component for your system.

Orientation Independence

Symmetric design means performance is the same in either orientation, simplifying assembly.

Center Thickness

Thinner at center than edges. Check minimum center thickness for structural integrity.

Combination Use

Pair with positive lenses for beam expanders, Galilean telescopes, and relay systems.

Applications

Laser Systems

Beam delivery, focusing, and conditioning for industrial and scientific laser systems.

Semiconductor

Wafer inspection, lithography support, and process control optics.

Machine Vision

Image formation in inspection systems and quality control cameras.

Research & Education

Laboratory optics, teaching setups, and experimental beam paths.

Manufacturing & Customization

PhotonEdge supports optical component sourcing, engineering review, and qualified manufacturing through our optical manufacturing network. We coordinate production, coating, and inspection to deliver components that meet your specifications.

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Prototype

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Low Volume

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Volume Production

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Custom Specification

Quality Assurance

Dimensional Inspection

Diameter, thickness, focal length verified per specification

Surface Quality

Scratch-dig inspection under calibrated illumination

Coating Verification

Spectrophotometric measurement of transmission/reflectance

Inspection documentation available according to project requirements. Certificates of Conformance, material test reports, and coating curves can be provided.

You May Also Need

Related Knowledge

Engineering Documentation

The following documentation is available upon request for qualified engineering projects:

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Dimensional Drawing

CAD & dimensional specs per your requirements

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Material Data Sheet

Material properties, transmission curves & certificates

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Coating Performance Curve

Spectrophotometric measurement data

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Inspection Report

Surface quality, flatness, centration & dimensional data

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Certificate of Conformance

CoC with full traceability per project requirements

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Custom Specification Sheet

Application-specific specification documentation

Documentation availability depends on project scope and order quantity. Request details during RFQ.

Frequently Asked Questions

What materials are available for this lens type?

We offer multiple substrate materials including N-BK7, UV Fused Silica, CaF₂, and Sapphire depending on your wavelength and environmental requirements.

Can I order custom specifications?

Yes. PhotonEdge offers custom diameters, focal lengths, coatings, and surface qualities. Custom specifications typically require 4-6 weeks lead time.

What surface quality should I specify?

40-20 is suitable for most laser and imaging applications. 20-10 is recommended for precision systems where scattering must be minimized.

What coating do I need?

The coating depends on your operating wavelength. For visible applications, AR 350-650nm is standard. For NIR lasers, choose the coating matching your wavelength. Uncoated is suitable for non-critical applications.

Do you provide inspection reports?

Yes. Dimensional reports, surface quality verification, and coating performance data are available according to project requirements.

How do I request a quote?

Click the 'Request Engineering Quote' button and provide your diameter, focal length, wavelength, coating, surface quality, and quantity.

When should I use bi-concave vs plano-concave?

Bi-concave for orientation-independent divergence; plano-concave when orientation is fixed and minimum aberration matters.

Not Sure Which Specification You Need?

Describe your optical system and our AI Optical Engineer will help identify the right specifications, materials, and coatings for your application.

Analyze My Requirement

Request an Engineering Quote

Provide your requirements and our engineering team will respond within 24 hours with a detailed quotation.

MaterialDiameterFocal LengthWavelengthSurface QualityFlatnessSymmetryCoatings

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