Mirror Substrate / Blank FAQ: What AR/VR Optics Buyers Ask

Optical designers sometimes treat mirrors as simple parts, yet in AR/VR Optics the mirror decides beam direction, loss budget and even image contrast. The Mirror…

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

Think of the Mirror Substrate / Blank as a precisely made BK7, fused silica, float glass or sapphire plate whose working surface is a uncoated or custom-coated. The result is n/a reflection across per specification, which is exactly what most AR/VR Optics builders are looking for.

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.

Most of the engineering in a Mirror Substrate / Blank lives in its uncoated or custom-coated. The stack is designed for per specification and delivers n/a, and its environmental protection layer keeps the metal from tarnishing so the mirror keeps working year after year.

A Mirror Substrate / Blank starts as a BK7, fused silica, float glass or sapphire blank. We hold it to λ/4 to λ/20 flatness and 20-10 / 40-20 surface quality, then apply the uncoated or custom-coated. The substrate never sees the beam directly, but its figure sets the limit on how straight the reflected wavefront stays.

When you specify a Mirror Substrate / Blank, the numbers that matter are flatness λ/4 to λ/20, finish 20-10 / 40-20, and the reflectance n/a across per specification. Thickness 0.5–25 mm is mostly about handling and mount compatibility, but it still belongs on the print. The specification table covers the common configurations.

Most AR/VR Optics engineers reach for a Mirror Substrate / Blank when they need packing seeing-through and see-through paths into a visor. The component's job is unglamorous but essential — keep the light on course and the loss low.

Frequently asked questions

Does a Mirror Substrate / Blank 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 (BK7, fused silica, float glass or sapphire) and uncoated or custom-coated are all adjustable. What reflectivity can I expect? Around n/a across per specification for standard builds.

For AR/VR Optics, do not over-specify. Choose the uncoated or custom-coated that covers per specification at the angle you use, keep flatness at λ/4 to λ/20 unless the wavefront demands more, and you will have a Mirror Substrate / Blank that is both capable and economical.

Mirrors reward careful handling. Hold a Mirror Substrate / Blank by the edges, keep the coated face away from fingers and aerosols, and clean only with approved optics tissue and solvent when truly needed. Store it in its packaging, coated face protected, and it will hold n/a for years.

Our production of a Mirror Substrate / Blank follows a simple, repeatable route: laser-cut the BK7, fused silica, float glass or sapphire to ±0.01 mm, smooth the edges, deposit the uncoated or custom-coated, and inspect to λ/4 to λ/20 / 20-10 / 40-20. Thickness options span 0.5–25 mm, and the same Hangzhou line that builds first-surface mirrors also runs windows, substrates and custom coatings.

The Mirror Substrate / Blank is not exclusive to AR/VR Optics. Universities, service centers and R&D groups use it wherever a beam must turn, which makes a flexible, customizable part a quiet workhorse across the optics world.

When you specify a Mirror Substrate / Blank, the numbers that matter are flatness λ/4 to λ/20, finish 20-10 / 40-20, and the reflectance n/a across per specification. Thickness 0.5–25 mm is mostly about handling and mount compatibility, but it still belongs on the print. The specification table covers the common configurations.

One term worth knowing

"Reflectivity" on a Mirror Substrate / Blank is the fraction of incident light returned by the uncoated or custom-coated. Quoting n/a without the band (per specification) is meaningless, because the same coating can be excellent at one wavelength and poor at another — always pair the number with the range.

A word on installation

When fitting a Mirror Substrate / Blank into AR/VR Optics hardware, handle it by the edges, seat it against a clean flat, and torque gently. Stress on the BK7, fused silica, float glass or sapphire shifts the figure and costs you the very flatness (λ/4 to λ/20) you paid for.

A Mirror Substrate / Blank is tougher than it looks but softer than you think. Fingerprints on the uncoated or custom-coated are the usual cause of field failures, so edge-handling and capped storage pay off. A little discipline keeps n/a where it belongs.

Typical specs worth putting on a drawing: surface flatness λ/4 to λ/20, surface quality 20-10 / 40-20 (scratch-dig), substrate BK7, fused silica, float glass or sapphire, thickness 0.5–25 mm, and reflectivity n/a over per specification. Stating these up front saves rounds of sampling later. Our full technical specifications and standard sizes list the tolerances we hold routinely.

Durability is part of the spec, not an afterthought. For AR/VR Optics the Mirror Substrate / Blank should survive shipping, installation and the occasional wipe. The protective overcoat on the uncoated or custom-coated is what lets it do that without losing n/a over time.

A short checklist covers most AR/VR Optics cases: what band (per specification)? at what angle? how much loss is allowed (n/a)? then pick uncoated or custom-coated on BK7, fused silica, float glass or sapphire at 0.5–25 mm. Getting these four right avoids the most common rework — the application notes show how each sector resolves them.

Mounting notes

A Mirror Substrate / Blank is only as good as its mount. Use edge contact rather than clamping the face, avoid over-tightening that bends the BK7, fused silica, float glass or sapphire and degrades λ/4 to λ/20, and keep the coated side clear of adhesive. In AR/VR Optics a kinematically supported mirror stays aligned through thermal cycles and shipping.

Substrate choice for a Mirror Substrate / Blank is a trade between optical grade and budget. BK7, fused silica, float glass or sapphire is a common pick because it can be cut and polished to λ/4 to λ/20 flatness and a 20-10 / 40-20 surface, which is plenty for the reflection quality most AR/VR Optics systems require.

Substrate choice for a Mirror Substrate / Blank is a trade between optical grade and budget. BK7, fused silica, float glass or sapphire is a common pick because it can be cut and polished to λ/4 to λ/20 flatness and a 20-10 / 40-20 surface, which is plenty for the reflection quality most AR/VR Optics systems require.

Beyond AR/VR Optics, the same Mirror Substrate / Blank shows up in laboratories, teaching setups and OEM builds where packing seeing-through and see-through paths into a visor. Its value is generality: one well-made part serves many breadboards, which is why stocking a few standard sizes pays off.

Wrapping up

A Mirror Substrate / Blank is a small part with an outsized effect on AR/VR Optics. Get the uncoated or custom-coated, BK7, fused silica, float glass or sapphire 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 — start from the specifications and standard sizes, then tell us the wavelength and angle.