IR Mirror FAQ: What Spectroscopy Buyers Ask

Optical designers sometimes treat mirrors as simple parts, yet in Spectroscopy the mirror decides beam direction, loss budget and even image contrast. The IR Mirror is a…

Optical designers sometimes treat mirrors as simple parts, yet in Spectroscopy the mirror decides beam direction, loss budget and even image contrast. The IR Mirror is a quietly critical component whose details repay careful attention.

At its core, the IR Mirror is a silicon, germanium or ZnSe element carrying a gold or dielectric for the infrared. That stack is engineered to return incident light efficiently over 700 nm – 10.6 µm, giving designers a predictable, low-loss way to steer a beam where they need it.

The working principle is the law of reflection applied to a coated plane. Mount the IR Mirror at 45° and a beam turns 90°; stack several and you fold a long path into a short box. That simplicity is why mirrors remain the fastest way to route light in Spectroscopy.

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.

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 Spectroscopy 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. The specification table covers the common configurations.

In Spectroscopy, the IR Mirror usually appears wherever directing and analyzing narrow wavelength bands. Designers value it because it keeps the beam path predictable and the loss budget small, which translates directly into a more stable instrument. The applications overview maps where each industry places it.

Frequently asked questions

Does a IR Mirror need a specific mount angle? Not inherently, but 0° or 45° are most common; tell your supplier the angle so the coating is optimized. Can it be customized? Yes — size, shape, substrate (silicon, germanium or ZnSe) and gold or dielectric for the infrared are all adjustable. What reflectivity can I expect? Around > 98% across 700 nm – 10.6 µm for standard builds.

For Spectroscopy, 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.

Treat the gold or dielectric for the infrared as the asset it is. In Spectroscopy service, a IR Mirror that is cleaned rarely and handled by the edge outlasts one that is wiped often. Less touching, more performance.

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.

How the part is checked

Before a IR Mirror leaves the line it is inspected for flatness (λ/4), finish (40-20) and reflectance (> 98% over 700 nm – 10.6 µm). A simple 45° visual check reveals coating defects, and a flatness test confirms the wavefront stays within tolerance — the same discipline JYOPTO applies across its optical glass, vacuum-coating and precision cold-processing since 2020.

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 Spectroscopy a kinematically supported mirror stays aligned through thermal cycles and shipping.

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. The specification table covers the common configurations.

The working principle is the law of reflection applied to a coated plane. Mount the IR Mirror at 45° and a beam turns 90°; stack several and you fold a long path into a short box. That simplicity is why mirrors remain the fastest way to route light in Spectroscopy.

One term worth knowing

"Reflectivity" on a IR Mirror is the fraction of incident light returned by the gold or dielectric for the infrared. Quoting > 98% without the band (700 nm – 10.6 µm) is meaningless, because the same coating can be excellent at one wavelength and poor at another — always pair the number with the range.

Beyond Spectroscopy, the same IR Mirror shows up in laboratories, teaching setups and OEM builds where directing and analyzing narrow wavelength bands. Its value is generality: one well-made part serves many breadboards, which is why stocking a few standard sizes pays off.

Environment matters. A IR Mirror headed for Spectroscopy may see condensation, vibration and frequent handling. Specifying a sealed-edge, protected coating and a stable silicon, germanium or ZnSe substrate means the mirror keeps its figure (λ/4) and its reflectance through warranty periods and beyond.

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.

A IR Mirror starts as a silicon, germanium or ZnSe blank. We hold it to λ/4 flatness and 40-20 surface quality, then apply the gold or dielectric for the infrared. The substrate never sees the beam directly, but its figure sets the limit on how straight the reflected wavefront stays.

Beyond Spectroscopy, the same IR Mirror shows up in laboratories, teaching setups and OEM builds where directing and analyzing narrow wavelength bands. Its value is generality: one well-made part serves many breadboards, which is why stocking a few standard sizes pays off.

Behind the coating sits the silicon, germanium or ZnSe substrate. Its job is mechanical: hold flatness, survive cutting and mounting, and stay stable with temperature. For many Spectroscopy uses, silicon, germanium or ZnSe hits the right balance of cost, flatness (λ/4) and workability.

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 Spectroscopy. See the standard size list for what we stock and what we cut to order.

Reflection on a first surface is straightforward physics: photons strike the coated face and are returned according to the law of reflection, angle in equals angle out. Because the coating sits on top, there is no second surface behind it to create a faint ghost image, which matters whenever contrast or measurement accuracy is at stake.

In short

For Spectroscopy, the IR Mirror is less a commodity than a tuned component. Specify the band (700 nm – 10.6 µm), the reflectivity (> 98%) and the figure (λ/4), and you will spend less time debugging light you cannot see. That is the whole game. Where your application sits among the sectors we serve changes the details, not the method.