Inside the IR Mirror: How It Works in 3D Scanning & Structured Light

Every 3D Scanning & Structured Light system eventually meets the same question: where does the light go, and how much of it survives the turn? A well-specified IR Mirror…

Every 3D Scanning & Structured Light system eventually meets the same question: where does the light go, and how much of it survives the turn? A well-specified IR Mirror answers both, which is why it earns a place on the bill of materials long before the enclosure is drawn.

Think of the IR Mirror as a precisely made silicon, germanium or ZnSe plate whose working surface is a gold or dielectric for the infrared. The result is > 98% reflection across 700 nm – 10.6 µm, which is exactly what most 3D Scanning & Structured Light builders are looking for.

When light meets the IR Mirror, almost all of it bounces from the front coating. The substrate merely holds the coating in place; it does not need to be traversed by the useful beam, so transmission losses and secondary reflections stay minimal — a real advantage in sensitive 3D Scanning & Structured Light setups.

Most of the engineering in a IR Mirror lives in its gold or dielectric for the infrared. The stack is designed for 700 nm – 10.6 µm and delivers > 98%, and its environmental protection layer keeps the metal from tarnishing so the mirror keeps working year after year.

Substrate choice for a IR Mirror is a trade between optical grade and budget. silicon, germanium or ZnSe is a common pick because it can be cut and polished to λ/4 flatness and a 40-20 surface, which is plenty for the reflection quality most 3D Scanning & Structured Light systems require.

When you specify a IR Mirror, the numbers that matter are flatness λ/4, finish 40-20, and the reflectance > 98% across 700 nm – 10.6 µm. Thickness 1–6 mm is mostly about handling and mount compatibility, but it still belongs on the print.

Where projecting and capturing patterned light accurately, a IR Mirror earns its place by doing one job reliably: turning the beam without adding noise. In 3D Scanning & Structured Light that reliability is the difference between a prototype and a shippable product.

Behind the performance

What reads on a datasheet as "> 98% over 700 nm – 10.6 µm" is really the outcome of interference. The gold or dielectric for the infrared on a silicon, germanium or ZnSe base is built layer by layer so reflected waves reinforce. Flatness λ/4 then keeps that wavefront from bending. The physics is old; the discipline to repeat it is the hard part.

For 3D Scanning & Structured Light, do not over-specify. Choose the gold or dielectric for the infrared that covers 700 nm – 10.6 µm at the angle you use, keep flatness at λ/4 unless the wavefront demands more, and you will have a IR Mirror that is both capable and economical.

A IR Mirror is tougher than it looks but softer than you think. Fingerprints on the gold or dielectric for the infrared are the usual cause of field failures, so edge-handling and capped storage pay off. A little discipline keeps > 98% where it belongs.

Our production of a IR Mirror follows a simple, repeatable route: laser-cut the silicon, germanium or ZnSe to ±0.01 mm, smooth the edges, deposit the gold or dielectric for the infrared, and inspect to λ/4 / 40-20. Thickness options span 1–6 mm, and the same Hangzhou line that builds first-surface mirrors also runs windows, substrates and custom coatings.

Coating a IR Mirror means laying down a gold or dielectric for the infrared whose optical thickness is controlled to a fraction of a wavelength. Done well, the part holds > 98% over 700 nm – 10.6 µm; done carelessly, it drifts and the system loses light it cannot afford to lose.

Selecting a IR Mirror for 3D Scanning & Structured Light starts with the wavelength and angle of incidence, then the acceptable loss. Match the gold or dielectric for the infrared to 700 nm – 10.6 µm, confirm > 98%, and make sure the silicon, germanium or ZnSe and 1–6 mm fit the mount you already have.

Coating a IR Mirror means laying down a gold or dielectric for the infrared whose optical thickness is controlled to a fraction of a wavelength. Done well, the part holds > 98% over 700 nm – 10.6 µm; done carelessly, it drifts and the system loses light it cannot afford to lose.

A practical IR Mirror datasheet reads: silicon, germanium or ZnSe substrate, λ/4 flatness, 40-20 quality, 1–6 mm thick, > 98% over 700 nm – 10.6 µm. Those five lines settle most design reviews for 3D Scanning & Structured Light.

Coating a IR Mirror means laying down a gold or dielectric for the infrared whose optical thickness is controlled to a fraction of a wavelength. Done well, the part holds > 98% over 700 nm – 10.6 µm; done carelessly, it drifts and the system loses light it cannot afford to lose.

Coating a IR Mirror means laying down a gold or dielectric for the infrared whose optical thickness is controlled to a fraction of a wavelength. Done well, the part holds > 98% over 700 nm – 10.6 µm; done carelessly, it drifts and the system loses light it cannot afford to lose.

Mounting notes

A IR Mirror is only as good as its mount. Use edge contact rather than clamping the face, avoid over-tightening that bends the silicon, germanium or ZnSe and degrades λ/4, and keep the coated side clear of adhesive. In 3D Scanning & Structured Light a kinematically supported mirror stays aligned through thermal cycles and shipping.

Substrate choice for a IR Mirror is a trade between optical grade and budget. silicon, germanium or ZnSe is a common pick because it can be cut and polished to λ/4 flatness and a 40-20 surface, which is plenty for the reflection quality most 3D Scanning & Structured Light systems require.

For 3D Scanning & Structured Light, do not over-specify. Choose the gold or dielectric for the infrared that covers 700 nm – 10.6 µm at the angle you use, keep flatness at λ/4 unless the wavefront demands more, and you will have a IR Mirror that is both capable and economical.

In 3D Scanning & Structured Light, the IR Mirror usually appears wherever projecting and capturing patterned light accurately. Designers value it because it keeps the beam path predictable and the loss budget small, which translates directly into a more stable instrument.

The gold or dielectric for the infrared is where performance is won or lost. Deposited by vacuum processes, it is tuned so the reflected wave adds constructively across 700 nm – 10.6 µm, reaching > 98%. Getting the layer thickness right is a precision task: a few nanometers off and the reflectivity curve shifts.

Wrapping up

A IR Mirror is a small part with an outsized effect on 3D Scanning & Structured Light. Get the gold or dielectric for the infrared, silicon, germanium or ZnSe and flatness right and the rest of the system behaves. If your drawing calls for something specific, the team at JYOPTO can cut and coat it to match.