Application of Tsingcarbo Light-Absorbing Coatings on Lens Retaining Rings

In any optical system — camera lenses, microscopes, or telescopes — the retaining ring sits at the very edge of the lens group. When stray light enters the lens, the retaining ring’s end face and inner wall are the first metal surfaces it encounters. If this surface is untreated or even moderately reflective, stray light reflects immediately, then bounces between the ring and lens elements, eventually reaching the image plane. The result: ghosting, flare, reduced contrast, and a hazy, washed-out image.

An effective approach to controlling stray light is to absorb it at the first point of contact — before it can propagate. That’s what high-performance light-absorbing materials can do on the retaining ring.Tsingcarbo® Black – Engineered for First-Contact Absorption

Suzhou Tsingcarbo Nanomaterials Co., Ltd., powered by Tsinghua University’s technical team, introduces Tsingcarbo® Black absorbing film and coating series. With hemispherical reflectance as low as <1% across a broad spectrum (200–2500nm), it absorbs over 99% of incident stray light.

For different retaining ring geometries, we offer two flexible solutions:

· Flexible absorbing film – 0.4mm thick, adhesive-backed, cuttable. Ideal for flat or moderately accessible ring surfaces. Easy to apply, maximum absorption.

· Precision spray coating – For narrow grooves, deep cavities, or irregular curved surfaces where tools or fingers cannot reach. The spray delivers the same high-performance absorbing layer, achieving >98.5% absorption even in the tightest spaces.

Both solutions are dust-free, non-outgassing (VOC-free), and operate reliably from -40°C to +120°C – meeting the stringent cleanliness requirements of automotive, security, aerospace, and high-end photographic lenses.

Why Start at the Retaining Ring?

Stopping stray light at the first bounce is more effective than addressing reflections later in the optical path. An untreated retaining ring can contribute to flare and reduced contrast in a premium lens. With Tsingcarbo® Black, retaining rings can serve as an effective first barrier against stray light.

Tsingcarbo® Black – Capture light, not ghosts.
Contact us for samples and custom solutions.