Custom achromatic doublets

Achromatic Doublets, Polished, Cemented and Centred in Rye

Kingsview Optical makes custom achromatic doublets to your drawing for OEMs, instrument makers and research labs. We polish both elements on our Optotech CNC lines, then cement and centre the pair on a Trioptics OptiCentric, so the finished doublet is measured as one optic before it leaves Rye.

  • Made in Rye, East Sussex
  • Cemented on a Trioptics OptiCentric
  • Coated in-house
  • ISO 9001:2015
Send Your Lens Drawing See the Specification
Trioptics OptiCentric used to cement and centre achromatic doublets in Rye
Cementing and centring on our Trioptics OptiCentric.
Lenses made here, start to finish. CNC polished, centred, coated and measured at our site in Rye.
See how we make them →
The basics

What an Achromatic Doublet Does

In short: an achromatic doublet is two lenses cemented together: a positive crown-glass element and a negative flint-glass element. Their dispersions cancel, so two wavelengths come to the same focus, and spherical aberration is far lower than in a single lens of the same focal length.

A single lens focuses blue light shorter than red light. Pairing a low-dispersion crown glass with a high-dispersion flint glass corrects that chromatic aberration, which is why doublets are the standard choice for imaging and for focusing broadband or multi-wavelength light.

Because the correction depends on the glass pair, the radii and the centration of the two elements, a custom doublet is only as good as its cementing. We cement with Norland 61 as standard and align the elements on the OptiCentric, which measures the centration of the cemented pair rather than each lens on its own.

Choose a custom doublet when catalogue diameters or focal lengths don't fit, when you need a particular glass pair or wavelength band, or when the doublet needs mechanical features such as a step, a flat or a blackened edge to fit your cell.

Cemented achromatic doublet: crown element (light) and flint element (dark).
Ray trace of an achromatic doublet bringing rays to a common focus
Ray trace of an achromatic doublet, from our optical design software.
Applications

Where Our Doublets Are Used

Imaging objectivesCamera, machine-vision and inspection optics where colour fringing matters.
Laser focusingFocusing several laser lines, or a laser plus an alignment beam, to one point.
CollimatorsCollimating light from fibres, LEDs and point sources across a wavelength band.
Relay opticsRelaying an image through an instrument with low aberration.
Scientific instrumentsMicroscope, spectroscopy and fluorescence optics.
Defence and securitySighting and imaging optics, from prototypes to production.
Specification

Achromatic Doublet Specification

These are our standard tolerances. If your design needs tighter, tell us which parameter. We'll tell you honestly whether we can hold it, and what it adds to cost.

Diameter range0.8mm to 100mm
Diameter tolerance+0 / −0.05mm
Centre thickness tolerance±0.05mm
Radius tolerance0.5% of radius or better
Irregularityλ/4
Centration (wedge)±2 arcmin
Surface quality (scratch-dig)60/40
ConstructionCemented crown and flint elements
AdhesiveNorland 61 as standard; NTT and others on request
Centration checkCemented pair measured on a Trioptics OptiCentric
MaterialsSchott, Ohara and CDGM optical glass; fused silica
CoatingsBroadband AR (standard 425 to 650nm, wider on request), V-coat, single-layer MgF2, custom designs
Edge finishingBlackened edges, steps, bevels, flats, controlled apertures

Not sure what to specify? For doublets, centration of the cemented pair and the glass choice usually matter more than tight cosmetic specs. Send the design and we'll help you check.

Options

Made to Fit Your System

CoatingsBroadband AR, V-coats and MgF2, applied in our own chambers
Edge featuresSteps, bevels, flats and blackened edges, CNC edged to suit your cell
Cells and housingsLens cells and barrels from our own machine shop AssemblyDoublets fitted into cells and complete lens assemblies
Questions

Achromatic Doublet Questions

How do I choose a doublet that fits a tight lens tube?
Start from the tube: the inside diameter sets the doublet's outside diameter, and the retaining ring or seat sets how much edge you need. Specify the clear aperture a little smaller than the diameter, so the ring clamps on an edge zone rather than the optical area. Make sure the edge thickness is enough for the ring to hold the lens without stress. Where space is very tight, a stepped or flat-faced edge can help. Send us the tube drawing and we'll design the edge to suit.
What drives the price of an achromatic doublet?
Diameter, how steep the radii are, the glass pair (some flint glasses cost more and are harder to polish), how tightly the cemented pair must be centred, the coating, the quantity, and whether you need inspection data with the parts.
I need a large-diameter doublet where wavefront quality matters more than appearance. How should I specify it?
Put the effort where it matters. Specify the surface form or wavefront you need and the centration of the cemented pair, and relax the scratch-dig spec if cosmetic appearance isn't critical. That keeps cost down without compromising performance. We measure surface form on our 4″ Zygo interferometer and centration on the OptiCentric.
When does a custom doublet make more sense than a catalogue one?
When the diameter or focal length you need isn't in a catalogue, when you need a specific glass pair or wavelength band, when the doublet needs mechanical features such as a step or a blackened edge, or when your volumes make a dedicated part cost-effective. Many customers prove the concept with a catalogue doublet, then move to a custom one for production.
I need to replace a damaged doublet in an existing instrument. What should I measure?
Record the outside diameter, the overall thickness, which way round it sits in the instrument, its focal length if you can measure it, and the colour of any coating.
Can I get a quote for a doublet with a specific diameter and focal length, including AR coating and inspection data?
Yes. Send the diameter, effective focal length, wavelength band, coating requirement and quantity, and say what inspection data you need. We coat in-house and can supply surface reports and coating witness samples with the parts.

Other Lenses We Manufacture

Plano-convex Plano-concave Biconvex Biconcave Meniscus Achromatic doublets Achromatic triplets

Or see our full precision optical lens manufacturing capability, and our optical design service if you need a lens designed.

Getting a Quote for Achromatic Doublets

Send us your drawing or lens design data. An engineer from the team that would make your lenses, not a sales team, will review it. They'll tell you plainly what's achievable and what will drive cost.

What to send

  • Drawing (PDF or ISO 10110), or diameter, focal length and wavelength band
  • Glass pair, if you have a preference
  • Centration and surface tolerances
  • Coating requirement
  • Quantities: prototypes and expected production volumes

What happens next

  1. An engineer reviews itWithin one working day, flagging anything that will drive cost or lead time.
  2. We quote the lensFor the prototype, and for production at your volumes.
  3. We make, measure and deliverAll in Rye, with inspection data if you need it.
Start Your RFQ

Need a Custom Achromatic Doublet?

Send your drawing or lens design data. We'll tell you honestly how we'd make it, what it will cost and how long it will take.

Send Your Lens Drawing Call 01797 226202
Made in Rye, East Sussex. NDA-friendly. Defence and security work welcome. ISO 9001:2015.