Bi-Convex Lenses

Name: Bi-Convex Lenses
Brand: PhotonEdge
SKU: PE-LENS-BCX-002
Availability: LimitedAvailability

Key Specifications

Material	N-BK7 (K9)
Diameter	5-100 mm
Focal Length	5-500 mm
Wavelength	350-2000 nm (VIS/NIR)
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-Convex Lenses?

Bi-convex (double convex) lenses have two convex surfaces with equal or near-equal radii of curvature. This symmetric design provides positive focal length and is optimal for 1:1 imaging (equal conjugate distances), where it minimizes spherical aberration.

BK7 bi-convex lenses are widely used in relay optics, beam focusing, and general-purpose imaging where the object and image distances are approximately equal.

When Should You Use This Product?

✔ Good Choice When

✓ 1:1 imaging with equal object-image distances
✓ Symmetric relay optics in multi-element systems
✓ General-purpose beam focusing
✓ Simple magnification or convergence

⚠ Consider an Alternative When

✗ Focusing collimated beams → Plano-Convex Lens

✗ Chromatic correction needed → Achromatic Doublet

✗ Diverging beam needed → Plano-Concave Lens

✗ High-NA low-aberration → Aspheric Lens

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.

Conjugate Ratio

Bi-convex lenses minimize spherical aberration at 1:1 conjugate ratio. For other ratios, orient the more curved surface toward the longer conjugate.

Center Thickness

Thicker than plano-convex lenses of equivalent focal length. Consider system space constraints.

Edge Thickness

Check minimum edge thickness for large diameters to ensure mechanical integrity.

AR Coatings

Both surfaces contribute to total reflection loss. BBAR coatings significantly improve throughput.

Applications

Imaging Systems

High-resolution image formation for industrial and scientific imaging.

Machine Vision

Inspection, measurement, and quality control in manufacturing.

Medical Devices

Optics for microscopy, endoscopy, and diagnostic imaging.

Research & Education

Laboratory setups and experimental optics.

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 a bi-convex vs plano-convex lens?

Bi-convex is optimal for 1:1 imaging. Plano-convex is better for collimated-to-focused applications.

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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