Sputtered interference filters

Dichroic Filters and Beamsplitters, Made in Rye

Kingsview Optical makes custom dichroic filters, mirrors and beamsplitters that reflect one band and transmit another, at the angle your system uses. We design them in-house, coat them by magnetron sputtering, dice or edge them to size and measure every batch at our site in Rye, East Sussex.

  • Magnetron sputtered in Rye
  • Diced in-house
  • Every batch measured
  • ISO 9001:2015
Send Your Filter Spec See the Specification
Vacuum coating chamber at Kingsview Optical in Rye, East Sussex
One of the vacuum coating chambers at our site in Rye.
Filters made here, start to finish. Designed, sputtered, diced and measured at our site in Rye.
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The basics

What a Dichroic Filter Does

In short: a dichroic filter splits light by wavelength. It is usually set at 45°, reflecting one band to the side and transmitting the rest straight through, so one beam becomes two colour channels, or two lasers become one beam.

Dichroics are interference coatings, so very little light is absorbed: what isn't transmitted is reflected. That makes them efficient beam splitters and combiners, and means the reflected beam is as useful as the transmitted one.

At 45°, S and P polarised light see the coating differently and the edge splits slightly between them. We design for your polarisation, or keep the split small for unpolarised light, and add an AR coating to the back face to stop ghost reflections.

Where the reflected beam is used for imaging, flatness matters as much as the coating. We polish substrates on our own lines, so flatness and coating are specified and checked together.

Mixed beamshort band reflectedlong band transmittedDichroic at 45°
At 45°, a dichroic reflects one band and transmits the other.
0%50%100%400450500550600650700Wavelength (nm)Transmission / reflectionReflected bandTransmitted bandEdge, designed at 45°Little is absorbed: R + T is close to 100%
Illustrative transmission and reflection curves for a longpass dichroic at 45°. Your dichroic is designed to your own wavelengths and measured on our Lambda 1050+.
Types

Dichroics We Make

Each dichroic is designed around the wavelengths you need to reflect and transmit, and the angle it works at. These are the families most of our enquiries fall into.

TypeWhat it doesTypical use
Longpass dichroicReflects shorter wavelengths and transmits longer ones.Fluorescence filter cubes, laser combining
Shortpass dichroicTransmits shorter wavelengths and reflects longer ones.Separating visible and NIR channels
Hot mirrorTransmits visible light and reflects infrared heat.Projectors, illumination, camera protection
Cold mirrorReflects visible light and transmits infrared, so heat passes out of the optical path.Lamp reflectors, illumination folds
Designed for your angleMost dichroics work at 45°, but any angle can be designed. Tell us the angle and cone angle so the edge lands where you need it.
Both faces matterThe coated face does the splitting. An AR coating on the back face stops ghost reflections in the transmitted beam.
Made in Rye

How We Make Your Dichroics

All four steps happen at our site in Rye, so you deal with one supplier, one purchase order and one lead time, from prototype lots to repeat production.

01DesignYour curve is modelled in Essential Macleod before anything goes in a chamber, so the quote comes with a target to measure against.
02SputterDense oxide multilayers deposited by magnetron sputtering at our site in Rye. Back-face AR added in-house if needed.
03DiceCoated wafers are diced to size on our Disco dicing saw for clean edges and full clear aperture. Glass can also be CNC edged to shape.
04MeasureEvery batch measured on a Perkin-Elmer Lambda 1050+. Measured-versus-design traces on request, with witness samples kept.
Applications

Where Our Dichroics Are Used

FluorescenceDichroic beamsplitters for filter cubes in microscopes and readers.
Laser combiningCombining several laser lines into one beam.
Multi-channel imagingSplitting visible and NIR, or colour channels, onto separate sensors.
IlluminationHot and cold mirrors that keep heat out of the optics.
Defence and securityChannel splitters for multi-sensor sights, made under NDA.
Machine visionCombining the illumination and imaging paths through one lens.
Specification

Dichroic Filter Specification

Every filter is designed to your numbers. These are typical figures; if your design needs tighter, tell us which parameter. We'll tell you plainly whether we can hold it, and what it adds to cost.

Angle of incidence45° standard; other angles designed to order
Edge position tolerance±3nm
Reflection bandTypically above 95% average
Transmission bandTypically above 90% average
PolarisationDesigned for unpolarised, S or P light
Back faceAR coated to suit the transmitted band
Wavelength range300 to 3000nm, from the UV through the visible to the SWIR
SubstratesFused silica, borosilicate and optical glass; we can coat your own substrate
SizeCoated on wafers up to 100mm diameter; diced filters from 0.8mm square, or single filters up to 100mm
Dimension tolerance±0.1mm standard; tighter on diced parts on request
Surface quality (scratch-dig)60/40 standard, 40/20 on request
MeasurementEvery batch on a Perkin-Elmer Lambda 1050+, 200 to 3000nm; traces on request

Not sure what to specify? Tell us the wavelengths to reflect and to transmit, the angle and the polarisation. We'll design the coating and send a modelled curve with the quote.

Questions

Dichroic Filter Questions

What is the difference between a dichroic filter and a dichroic mirror?
They are the same kind of coating. "Dichroic mirror" usually means the reflected beam is the one used, "dichroic filter" the transmitted one, and "dichroic beamsplitter" when both beams are used.
Why does a dichroic behave differently at 45 degrees?
Interference coatings depend on angle. At 45° the edge sits at a shorter wavelength than at normal incidence, and S and P polarisation separate. A dichroic must be designed for the angle it will be used at.
What is a hot mirror?
A dichroic that transmits visible light and reflects infrared. It keeps heat away from sensitive optics in projectors and illumination systems. A cold mirror does the reverse.
Do I need an AR coating on the back face?
Usually yes, if you use the transmitted beam. Without it the back face reflects a few percent and can create ghost images. We apply both coatings in-house.
Can you make dichroics for imaging?
Yes. For reflected imaging, substrate flatness and thickness matter as well as the coating. Tell us the beam size and wavefront requirement and we'll specify both.
What do you need to quote a dichroic?
The wavelengths to reflect and transmit, the angle of incidence, polarisation, size, thickness, back face coating and quantity.

Related Filters and Coatings

Custom optical filtersAll our sputtered and coloured glass filters, and how we make them Longpass and shortpass filtersSteep edge filters, IR cut filters and hot mirrors Bandpass filtersNarrowband, laser line, broadband and fluorescence filters Optical coating serviceAR, mirror and sputtered coatings applied in our own chambers

Getting a Quote for Custom Dichroics

Send the spectral requirement, even as a sketch of the curve. An engineer from the team that would make your filters, not a sales team, will review it and tell you plainly what's achievable and what will drive cost.

What to send

  • Wavelengths to reflect and to transmit
  • Angle of incidence and polarisation
  • Size, thickness, and flatness if imaging
  • Back face coating
  • Quantities: prototypes and expected production volumes

What happens next

  1. An engineer reviews itWithin one working day, confirming it's achievable and flagging anything that will drive cost or lead time.
  2. We model it and quoteThe quote comes with a modelled target curve to measure against.
  3. We coat, dice and measureAll in Rye, with measured traces if you need them.
Start Your Filter RFQ

Need a Dichroic Designed for Your Angle?

That's what our sputtering chamber is for. Send the curve you need and we'll come back with a design, a price and a lead time.

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