Case Study: Hot Mirror for 3D Scanning & Structured Light

Optical designers sometimes treat mirrors as simple parts, yet in 3D Scanning & Structured Light the mirror decides beam direction, loss budget and even image contrast.…

Optical designers sometimes treat mirrors as simple parts, yet in 3D Scanning & Structured Light the mirror decides beam direction, loss budget and even image contrast. The Hot Mirror is a quietly critical component whose details repay careful attention.

A Hot Mirror is an optical component built so that reflection happens at the coated front face rather than through a substrate. With a dichroic (transmits visible, reflects IR) on a float or borosilicate glass base, the part delivers > 90% visible transmit reflectivity across IR reflect / visible pass while keeping the useful aperture clean and ghost-free.

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.

Coating a Hot Mirror means laying down a dichroic (transmits visible, reflects IR) whose optical thickness is controlled to a fraction of a wavelength. Done well, the part holds > 90% visible transmit over IR reflect / visible pass; done carelessly, it drifts and the system loses light it cannot afford to lose.

Behind the coating sits the float or borosilicate glass substrate. Its job is mechanical: hold flatness, survive cutting and mounting, and stay stable with temperature. For many 3D Scanning & Structured Light uses, float or borosilicate glass hits the right balance of cost, flatness (4–6λ) and workability.

When you specify a Hot Mirror, the numbers that matter are flatness 4–6λ, finish 60-40, and the reflectance > 90% visible transmit across IR reflect / visible pass. Thickness 1–3 mm is mostly about handling and mount compatibility, but it still belongs on the print. The specification table covers the common configurations.

Where projecting and capturing patterned light accurately, a Hot 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. More application examples are worth a look if the use case is close to yours.

From problem to part

A team in 3D Scanning & Structured Light kept fighting beam drift while projecting and capturing patterned light accurately. The fix was a dedicated Hot Mirror: dichroic (transmits visible, reflects IR) matched to IR reflect / visible pass, edges safe, cut to ±0.01 mm. Once the mirror matched the drawing instead of the catalog, their yield improved and support calls dropped.

Selecting a Hot Mirror for 3D Scanning & Structured Light starts with the wavelength and angle of incidence, then the acceptable loss. Match the dichroic (transmits visible, reflects IR) to IR reflect / visible pass, confirm > 90% visible transmit, and make sure the float or borosilicate glass and 1–3 mm fit the mount you already have. The spec and size tables make that comparison quick.

Treat the dichroic (transmits visible, reflects IR) as the asset it is. In 3D Scanning & Structured Light service, a Hot Mirror that is cleaned rarely and handled by the edge outlasts one that is wiped often. Less touching, more performance.

Because we control cutting, coating and finishing in one place, a Hot Mirror can move from your drawing to a finished part without hand-offs. The float or borosilicate glass is cut to ±0.01 mm, the dichroic (transmits visible, reflects IR) is vacuum-deposited for > 90% visible transmit over IR reflect / visible pass, and the result is inspected to 4–6λ flatness and 60-40 quality.

A Hot Mirror starts as a float or borosilicate glass blank. We hold it to 4–6λ flatness and 60-40 surface quality, then apply the dichroic (transmits visible, reflects IR). The substrate never sees the beam directly, but its figure sets the limit on how straight the reflected wavefront stays.

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 Hot Mirror answers both, which is why it earns a place on the bill of materials long before the enclosure is drawn.

In real service a Hot Mirror meets more than the optical table. Humidity, temperature swings and routine cleaning all test the dichroic (transmits visible, reflects IR). A good protective layer keeps the metal from oxidizing, so the part holds > 90% visible transmit across IR reflect / visible pass for years rather than months — exactly what 3D Scanning & Structured Light equipment that ships to varied climates needs.

Behind the coating sits the float or borosilicate glass substrate. Its job is mechanical: hold flatness, survive cutting and mounting, and stay stable with temperature. For many 3D Scanning & Structured Light uses, float or borosilicate glass hits the right balance of cost, flatness (4–6λ) and workability.

A word on installation

When fitting a Hot Mirror into 3D Scanning & Structured Light hardware, handle it by the edges, seat it against a clean flat, and torque gently. Stress on the float or borosilicate glass shifts the figure and costs you the very flatness (4–6λ) you paid for.

In 3D Scanning & Structured Light, the Hot 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 applications overview maps where each industry places it.

Environment matters. A Hot Mirror headed for 3D Scanning & Structured Light may see condensation, vibration and frequent handling. Specifying a sealed-edge, protected coating and a stable float or borosilicate glass substrate means the mirror keeps its figure (4–6λ) and its reflectance through warranty periods and beyond.

Mounting notes

A Hot Mirror is only as good as its mount. Use edge contact rather than clamping the face, avoid over-tightening that bends the float or borosilicate glass and degrades 4–6λ, and keep the coated side clear of adhesive. In 3D Scanning & Structured Light a kinematically supported mirror stays aligned through thermal cycles and shipping.

Beyond 3D Scanning & Structured Light, the same Hot Mirror shows up in laboratories, teaching setups and OEM builds where projecting and capturing patterned light accurately. Its value is generality: one well-made part serves many breadboards, which is why stocking a few standard sizes pays off.

Most 3D Scanning & Structured Light engineers reach for a Hot Mirror when they need projecting and capturing patterned light accurately. The component's job is unglamorous but essential — keep the light on course and the loss low.

Selecting a Hot Mirror for 3D Scanning & Structured Light starts with the wavelength and angle of incidence, then the acceptable loss. Match the dichroic (transmits visible, reflects IR) to IR reflect / visible pass, confirm > 90% visible transmit, and make sure the float or borosilicate glass and 1–3 mm fit the mount you already have. The spec and size tables make that comparison quick.

In short

For 3D Scanning & Structured Light, the Hot Mirror is less a commodity than a tuned component. Specify the band (IR reflect / visible pass), the reflectivity (> 90% visible transmit) and the figure (4–6λ), 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.