Achromatic Doublet Lenses

Name: Achromatic Doublet Lenses
Brand: PhotonEdge
SKU: PE-LENS-ACH-005
Availability: LimitedAvailability

Key Specifications

Type	Achromatic Doublet (Cemented/Air-Spaced)
Material Pair	N-BK7 + SF N (others available)
Diameter	3-100 mm
Focal Length	5-500 mm
Wavelength	400-700 nm (visible, corrected)
Surface Quality	40-20 / 20-10
Flatness	λ/4 @ 632.8nm per element
Correction	Axial chromatic at 2 wavelengths

What Is a Achromatic Doublet Lenses?

An achromatic doublet consists of two lens elements made from different optical glass types (typically a positive crown element cemented to a negative flint element). The combination corrects chromatic aberration at two wavelengths, bringing them to a common focal point.

This correction dramatically improves image quality in broadband illumination compared to single-element lenses, making doublets essential for machine vision, microscopy, and scientific imaging.

When Should You Use This Product?

✔ Good Choice When

✓ Broadband imaging where color fringing must be minimized
✓ Machine vision systems requiring high-resolution across visible spectrum
✓ Microscopy and medical imaging optics
✓ Collimation of multi-wavelength or white-light sources

⚠ Consider an Alternative When

✗ Single-wavelength laser application → Plano-Convex Lens (BK7)

✗ UV or IR wavelengths → UV Fused Silica Lens

✗ Very high NA or minimal spherical aberration → Aspheric Lens

✗ Budget-critical low-resolution application → Singlet Lens

Available Optical Materials

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

Material	Transmission	Key Advantage	Considerations
N-BK7 + SF N	VIS (400-700nm)	Standard achromatic pair, excellent availability	Limited to visible
N-BK7 + SF10	VIS (400-700nm)	Higher dispersion correction	Slightly higher cost
UV Fused Silica + UV Grade	UV/VIS (250-700nm)	UV-compatible achromatic designs	Premium cost
CaF₂ + Glass	UV/VIS/NIR (250-1500nm)	Broadband correction into NIR	Special order

Not sure which material to choose?

Ask AI Optical Engineer

Optical Coating Options

BBAR Visible

Broadband AR for 400-700nm. R < 0.5% per surface.

Typical use: General visible imaging and machine vision

BBAR VIS-NIR

Broadband AR from 400-950nm.

Typical use: Multi-spectral imaging, silicon detector applications

AR Custom Wavelength

Custom AR for specific wavelength bands.

Typical use: Specialized fluorescence or laser applications

Uncoated

No AR. ~4% reflection per surface (4 surfaces ~15% loss).

Typical use: Non-critical or alignment 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.

Chromatic Correction

Corrects axial chromatic aberration at two wavelengths (typically 486nm and 656nm). Residual secondary spectrum is ~10x less than a singlet.

Focal Length Tolerance

Standard ±1%. Request ±0.5% or tighter for precision imaging.

Cemented vs Air-Spaced

Cemented: compact, economical. Air-spaced: better correction, larger, more expensive.

Orientation

Orient the more curved element toward longest conjugate distance. Follow manufacturer orientation marks.

Temperature

Standard cemented: -40°C to +80°C. Extended range on request.

Clear Aperture

Typically > 90% of nominal diameter. Edge region may have degraded correction.

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.

What is an achromatic doublet?

A two-element lens correcting chromatic aberration at two wavelengths, reducing color fringing in broadband imaging.

Cemented vs air-spaced?

Cemented: compact and economical. Air-spaced: better correction but larger and more expensive.

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.

TypeMaterial PairDiameterFocal LengthWavelengthSurface QualityFlatnessCorrection

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