A SWIR Copy Lens That Helps Expose Art Forgeries
A UK camera company needed a short-wave infrared version of its 75mm visible copy lens, for imaging artwork to check it is genuine. We designed it for the 900–1700nm band, then made the lenses, SWIR coatings, metalwork and clicking iris in Rye. Delivered in 10 weeks, and followed by an order for 50 more.
Taking a Visible Copy Lens Into the Short-Wave Infrared
Short-wave infrared imaging can see beneath the surface layers of a painting, revealing underdrawings and how a work was made. That makes it a valuable tool for checking whether an artwork is genuine.
The customer already had a 75mm copy lens for visible light and wanted a SWIR replacement for the same job.
The new lens had to:
- Work across the full 900–1700nm SWIR band
- Image a 50×50mm area onto a 104×104mm sensor, roughly 2:1
- Hold a 200mm working distance from the artwork
- Offer an F/8 to F/22 iris with a positive click at each setting
- Fit the camera's M50×0.75 screw mount
A 75mm copy lens whose design and coatings were optimised for the visible band, not the short-wave infrared.
Optics designed for the SWIR band, made from SWIR-suitable materials with multilayer SWIR coatings, all produced in Rye.
Optics, Coatings and Mechanics Built for the SWIR Band
A SWIR lens is more than a visible lens with new glass. The design, the choice of materials and the anti-reflection coatings all have to work across 900–1700nm. Because we make lenses in SWIR materials and apply multilayer SWIR coatings ourselves, we could control every part of that in house.
A Clicking Iris
The customer needed to set the aperture between F/8 and F/22 repeatably. We built a clicking iris into the metalwork, so each setting locates with a positive click, and laser engraved the markings in house.
Made in Rye, Start to Finish
Every stage was carried out at our site in Rye, East Sussex: design, lens manufacture, SWIR coating, metalwork, engraving and assembly. Nothing was sent out.
- Optical designSWIR lens design and Monte Carlo tolerance analysis in Zemax.
- Lens manufactureSWIR-suitable materials polished on our Optotech CNC lines.
- SWIR coatingsMultilayer anti-reflection coatings for 900–1700nm.
- MetalworkHousing, clicking iris and M50 mount, laser engraved on site.
- AssemblyAssembled and checked in house before delivery.
From Design Analysis to Customer Approval
- 01
Predicted in Design
Monte Carlo tolerance analysis confirmed the SWIR design would hold its performance once made.
- 02
Iris Checked in Rye
Every assembly was checked for a clean, positive click at each aperture setting.
- 03
Tested on the Customer's Camera
The customer tested the lens on their own SWIR camera, approved the design and ordered 50 more.
A SWIR copy lens designed and delivered in 10 weeks. After testing it on their own camera, the customer approved the design and ordered 50 more lens assemblies.
Need a Lens for the Short-Wave Infrared?
Tell us your wavelength range, your sensor and what you need to see. An engineer who works beside our production line will tell you what is possible, from a single prototype to a production run.
We reply within one working day. All projects can be handled under NDA.