Sputtered interference filters

Longpass and Shortpass Filters, Sputtered in Rye

Kingsview Optical makes custom longpass and shortpass edge filters with the edge exactly where your system needs it. We design them in-house, coat them by magnetron sputtering, dice 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
Disco dicing saw used to dice sputtered optical filters at Kingsview Optical
Coated wafers are diced into filters on our Disco dicing saw.
Filters made here, start to finish. Designed, sputtered, diced and measured at our site in Rye.
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The basics

What Longpass and Shortpass Filters Do

In short: a longpass filter transmits wavelengths longer than its edge and blocks shorter ones. A shortpass filter does the opposite. You specify the edge position, how steep it is, and how far the blocking extends.

Longpass filters are named by their cut-on wavelength, where transmission reaches half its peak. Shortpass filters are named by their cut-off. Edge steepness is usually quoted as the distance from 10% to 90% transmission.

Interference edge filters reflect the blocked light rather than absorbing it, and their edges are much steeper than coloured glass. They can also be placed at any wavelength, not just where a glass happens to cut on. For absorbing glass, see our Schott KG heat absorbing filters.

Every interference edge filter blocks over a finite range. A shortpass filter in particular needs its blocking extended across the whole range your detector sees. We design the blocking around your source and detector so nothing leaks through at the far end.

SourceLongpass filterlonger wavelengths passreflectedreflected
A longpass filter transmits the longer wavelengths and reflects the shorter ones.
0%50%100%400450500550600650700750Wavelength (nm)TransmissionCut-off (50%)Cut-on (50%)ShortpassLongpassEdge steepness, 10% to 90%
Illustrative shortpass and longpass curves. Your filter is designed to your own edge position and measured on our Lambda 1050+.
Types

Edge Filters We Make

Each edge filter is designed around the wavelengths you need to pass and to block. These are the families most of our enquiries fall into.

TypeWhat it doesTypical use
LongpassTransmits above the cut-on edge and blocks below it.Fluorescence emission, excitation rejection, NIR imaging
ShortpassTransmits below the cut-off edge and blocks above it.Excitation filters, IR rejection, illumination
IR cutA shortpass filter that passes visible light and blocks near-infrared, so a silicon sensor sees true colour.Colour cameras and machine vision
Hot mirrorA shortpass coating that reflects infrared heat away from the optics while passing visible light.Projectors, illumination, lamp housings
Coated coloured glassA sputtered edge coating on Schott absorbing glass. The glass keeps blocking over a wide range of angles, where a dielectric filter alone is angle dependent.Wide-angle and fast optics, cameras and sensors
Edge position and steepnessSteeper edges and tighter edge tolerances take more layers. Tell us the wavelengths that must pass and the ones that must be blocked, and we'll set the edge between them.
Wide angle with coloured glassRegular dielectric filters are angle dependent: the edge moves as the angle changes. Schott glass absorbs rather than reflects, so a sputtered coating on coloured glass keeps working over a wide angle range, with the steep edge of the coating and the broad blocking of the glass.
Made in Rye

How We Make Your Edge Filters

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 Longpass and Shortpass Filters Are Used

FluorescenceLongpass emission filters and shortpass excitation filters.
Colour camerasIR cut filters that give silicon sensors a true colour response.
NIR and night imagingLongpass filters that block visible light for NIR cameras.
IlluminationRemoving heat or UV from lamp and LED light.
Defence and securityEdge filters for sights and sensors, made under NDA.
SpectroscopyOrder sorting and stray light rejection in spectrometers.
Specification

Longpass and Shortpass 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.

Edge position tolerance±3nm
Edge steepness (10% to 90%)Typically within 2% of the edge wavelength
Passband transmissionTypically above 90% average
BlockingUp to OD6, extended over the range your detector sees
Angle of incidence0° standard; 45° and other angles designed to order
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 which wavelengths must pass, which must be blocked, and your detector. We'll set the edge between them and send a modelled curve with the quote.

Questions

Longpass and Shortpass Filter Questions

What is the difference between a longpass and a shortpass filter?
A longpass filter transmits wavelengths longer than its edge and blocks shorter ones. A shortpass filter transmits wavelengths shorter than its edge and blocks longer ones.
What does cut-on wavelength mean?
The wavelength at which a longpass filter reaches half its peak transmission. For a shortpass filter the same point is called the cut-off.
Why choose an interference edge filter over coloured glass?
Interference edges are steeper and can be placed at any wavelength, but they shift with angle of incidence. Coloured glass blocks broadly and works over a wide range of angles, but only comes with fixed cut-on points. We make both, and can put a sputtered edge on coloured glass to get the benefits of each.
What is an IR cut filter?
A shortpass filter that transmits visible light and blocks near-infrared, usually above about 650 to 700nm. It stops silicon camera sensors picking up infrared and giving false colours.
Does the angle of incidence move the edge?
Yes, to shorter wavelengths as the angle increases, and at large angles the edge splits for S and P polarisation. We design for the angle in your system.
What do you need to quote an edge filter?
The edge wavelength and tolerance, which side transmits, the blocking range and OD, angle of incidence, size, thickness and quantity.

Related Filters and Coatings

Custom optical filtersAll our sputtered and coloured glass filters, and how we make them Bandpass filtersNarrowband, laser line, broadband and fluorescence filters Notch filtersLaser line and Raman notch filters with clear passbands Optical coating serviceAR, mirror and sputtered coatings applied in our own chambers

Getting a Quote for Longpass and Shortpass Filters

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

  • Edge wavelength, tolerance and steepness
  • Wavelengths to transmit and to block
  • Blocking range and optical density
  • Angle of incidence, size and thickness
  • 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 an Edge Filter in the Right Place?

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.