Case Study: Protected Gold Mirror for Projection & Display

For engineers working in Projection & Display, the choice of a reflective surface is rarely an afterthought. Protected Gold Mirror components sit at the heart of systems…

For engineers working in Projection & Display, the choice of a reflective surface is rarely an afterthought. Protected Gold Mirror components sit at the heart of systems where routing and combining light engines in compact housings, and a small improvement in coating quality can change the result of an entire measurement or process.

Think of the Protected Gold Mirror as a precisely made silicon, copper or glass plate whose working surface is a protected gold. The result is 98%+ in the IR reflection across 700 nm to 10.6 µm, which is exactly what most Projection & Display builders are looking for.

The working principle is the law of reflection applied to a coated plane. Mount the Protected Gold 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 Projection & Display.

Most of the engineering in a Protected Gold Mirror lives in its protected gold. The stack is designed for 700 nm to 10.6 µm and delivers 98%+ in the IR, and its environmental protection layer keeps the metal from tarnishing so the mirror keeps working year after year.

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

Typical specs worth putting on a drawing: surface flatness λ/4, surface quality 40-20 (scratch-dig), substrate silicon, copper or glass, thickness 0.5–6 mm, and reflectivity 98%+ in the IR over 700 nm to 10.6 µm. Stating these up front saves rounds of sampling later.

Where routing and combining light engines in compact housings, a Protected Gold Mirror earns its place by doing one job reliably: turning the beam without adding noise. In Projection & Display that reliability is the difference between a prototype and a shippable product.

From problem to part

A team in Projection & Display kept fighting beam drift while routing and combining light engines in compact housings. The fix was a dedicated Protected Gold Mirror: protected gold matched to 700 nm to 10.6 µm, edges safe, cut to ±0.01 mm. Once the mirror matched the drawing instead of the catalog, their yield improved and support calls dropped.

For Projection & Display, do not over-specify. Choose the protected gold that covers 700 nm to 10.6 µm at the angle you use, keep flatness at λ/4 unless the wavefront demands more, and you will have a Protected Gold Mirror that is both capable and economical.

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

Our production of a Protected Gold Mirror follows a simple, repeatable route: laser-cut the silicon, copper or glass to ±0.01 mm, smooth the edges, deposit the protected gold, and inspect to λ/4 / 40-20. Thickness options span 0.5–6 mm, and the same Hangzhou line that builds first-surface mirrors also runs windows, substrates and custom coatings.

Selecting a Protected Gold Mirror for Projection & Display starts with the wavelength and angle of incidence, then the acceptable loss. Match the protected gold to 700 nm to 10.6 µm, confirm 98%+ in the IR, and make sure the silicon, copper or glass and 0.5–6 mm fit the mount you already have.

How the part is checked

Before a Protected Gold Mirror leaves the line it is inspected for flatness (λ/4), finish (40-20) and reflectance (98%+ in the IR over 700 nm to 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.

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

Where routing and combining light engines in compact housings, a Protected Gold Mirror earns its place by doing one job reliably: turning the beam without adding noise. In Projection & Display that reliability is the difference between a prototype and a shippable product.

A word on installation

When fitting a Protected Gold Mirror into Projection & Display hardware, handle it by the edges, seat it against a clean flat, and torque gently. Stress on the silicon, copper or glass shifts the figure and costs you the very flatness (λ/4) you paid for.

Most of the engineering in a Protected Gold Mirror lives in its protected gold. The stack is designed for 700 nm to 10.6 µm and delivers 98%+ in the IR, and its environmental protection layer keeps the metal from tarnishing so the mirror keeps working year after year.

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

At its core, the Protected Gold Mirror is a silicon, copper or glass element carrying a protected gold. That stack is engineered to return incident light efficiently over 700 nm to 10.6 µm, giving designers a predictable, low-loss way to steer a beam where they need it.

How the part is checked

Before a Protected Gold Mirror leaves the line it is inspected for flatness (λ/4), finish (40-20) and reflectance (98%+ in the IR over 700 nm to 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.

For Projection & Display, do not over-specify. Choose the protected gold that covers 700 nm to 10.6 µm at the angle you use, keep flatness at λ/4 unless the wavefront demands more, and you will have a Protected Gold Mirror that is both capable and economical.

For Projection & Display, do not over-specify. Choose the protected gold that covers 700 nm to 10.6 µm at the angle you use, keep flatness at λ/4 unless the wavefront demands more, and you will have a Protected Gold Mirror that is both capable and economical.

Quality control

Every Protected Gold Mirror is measured, not just sampled. Flatness against a reference, scratch-dig against 40-20, and a reflectance spot-check at 700 nm to 10.6 µm confirm the protected gold performed as designed. Documented results matter most for Projection & Display, where one bad part can stall a whole instrument.

At JYOPTO we make Protected Gold Mirror parts by cutting silicon, copper or glass with laser accuracy of ±0.01 mm, then applying the protected gold under vacuum. Standard blanks run 0.5–6 mm thick, edges are smoothed for safe handling, and every shipped mirror meets λ/4 flatness with a 40-20 surface — the same disciplines we apply across our optical glass, vacuum-coating and precision cold-processing lines since 2020.

Wrapping up

A Protected Gold Mirror is a small part with an outsized effect on Projection & Display. Get the protected gold, silicon, copper or glass 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.