Sputtered interference filters

Custom Notch Filters, Sputtered in Rye

Kingsview Optical makes custom notch filters that block a laser line, or any narrow band, while transmitting the wavelengths either side. 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
Sputtered optical filter wafer diced into individual filters at Kingsview Optical
A sputtered filter wafer, diced into individual filters in Rye.
Filters made here, start to finish. Designed, sputtered, diced and measured at our site in Rye.
See all our optical filters →
The basics

What a Notch Filter Does

In short: a notch filter is the opposite of a bandpass filter. It blocks one narrow band, usually a laser wavelength, and transmits the light either side, so you can see a weak signal right next to a bright laser.

Our notch filters are multilayer interference coatings. The layers are designed to reflect a narrow band very strongly while keeping the passbands either side clear and flat. The depth of the notch is quoted as optical density (OD) at the laser wavelength.

The classic use is Raman spectroscopy, where the Raman signal is far weaker than the laser that excites it. A deep notch removes the laser and lets the shifted light through. The same idea keeps a known laser line out of cameras and detectors.

The notch moves to shorter wavelengths as the filter tilts, so the design has to allow for the angle of incidence and any tolerance on the laser wavelength. Tell us both and we'll size the notch to suit.

Laser + signalNotch filterlaser line reflectedsignal passes either side
A notch filter reflects the laser line and transmits the light either side.
0%50%100%400450500550600650700Wavelength (nm)TransmissionLaser lineNotch widthDepth: OD at the laser linePassbandPassband
Illustrative curve showing the figures you specify. Your filter is designed to your own numbers and measured on our Lambda 1050+.
Types

Notch Filters We Make

Each notch filter is designed around your laser and your signal. These are the families most of our enquiries fall into.

TypeWhat it doesTypical use
Laser line notchA single deep notch at your laser wavelength, for example 405, 532, 633 or 785nm, with clear passbands either side.Laser rejection in imaging and detection
Raman notchA deep notch with steep edges, so Raman lines close to the laser are still transmitted.Raman spectroscopy and analysers
Sensor protectionBlocks a known laser wavelength in front of a camera or detector while the rest of the scene stays visible.Cameras and sensors near laser systems
Fluorescence notchRemoves the excitation line from the emission path.Fluorescence imaging and diagnostics
Notch width versus edge steepnessA narrower notch lets you see closer to the laser, but needs a steeper, more complex design. Tell us how close to the laser you need to measure.
Allow for angle and laser driftWe size the notch so the laser stays blocked across your angle of incidence and the laser's wavelength tolerance.
Made in Rye

How We Make Your Notch 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 Notch Filters Are Used

Raman spectroscopyRemoving the excitation laser so weak Raman lines can be measured.
Camera and detector protectionKeeping a known laser line from saturating sensors.
FluorescenceRejecting the excitation line in microscopes and readers.
Defence and securityLaser rejection in sights and surveillance optics, made under NDA.
Industrial inspectionRejecting process lasers so cameras can watch cutting, welding and marking.
Scientific instrumentsLaser rejection in research optics and spectrometers.
Specification

Notch 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.

Notch centre tolerance±2nm
Notch widthFrom about 20nm, measured at the blocking level you specify
Notch depthUp to OD6 at the laser wavelength
Passband transmissionTypically above 90% average either side of the notch
Angle of incidence0° standard; 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 the laser wavelength and its tolerance, how close to the laser you need to measure, and your angle of incidence. We'll design the notch and send a modelled curve with the quote.

Questions

Notch Filter Questions

What is the difference between a notch filter and a bandpass filter?
A bandpass filter transmits one band and blocks everything else. A notch filter does the reverse: it blocks one narrow band and transmits everything either side.
What OD do I need for Raman spectroscopy?
Raman signals are very weak, so OD6 at the laser line is common. For less demanding laser rejection OD4 is often enough. Tell us your laser power and detector and we'll suggest a depth.
Can a notch filter protect a camera or sensor?
Yes. A notch at the laser wavelength stops a known laser line from saturating a camera or detector while the rest of the scene stays visible. Tell us the laser wavelength and power.
How close to the laser line can I see?
That depends on the notch width and edge steepness. Steeper edges let you see closer to the laser but need a more complex design. Tell us the closest wavelength you need to transmit.
Does tilting the filter move the notch?
Yes. The notch moves to shorter wavelengths as the angle increases. We design for the angle in your system and can widen the notch to allow for tolerance.
What do you need to quote a notch filter?
The laser wavelength and its tolerance, the OD you need, the passband range either side, the 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 Longpass and shortpass filtersSteep edge filters, IR cut filters and hot mirrors Optical coating serviceAR, mirror and sputtered coatings applied in our own chambers

Getting a Quote for Custom Notch 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

  • Laser wavelength and its tolerance
  • Optical density needed at the laser line
  • Passband range and minimum transmission either side
  • 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 a Notch Filter for Your Laser?

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.