Optical Coating
Precision thin-film deposition for controlled optical performance.
Optical Coating Capabilities
Optical coatings modify the way a surface transmits and reflects light, from reducing unwanted reflections to selecting specific wavelength bands. Strahl Optics coordinates anti-reflection, reflective, and wavelength-selective coatings for different substrates and component designs. The coating configuration takes account of the operating wavelengths, angle of incidence, polarization, and conditions of use.
Substrate Preparation & Loading
Before deposition, optical surfaces are cleaned to remove residues and particles that can affect coating adhesion and introduce defects. Substrates are then positioned in suitable holders, with masking applied where specified.
The loading arrangement exposes the required coating area and supports consistent coverage across the usable surface.
Thin-Film Deposition
Selected coating materials are deposited onto the substrate as thin layers within a vacuum chamber. Layer composition, thickness, and sequence establish the coating’s optical response.
For custom optical mirrors, these choices determine the reflection band and its dependence on angle and polarization, while protective overcoats can improve the durability of metallic surfaces.
Post-Coating Cutting
For components produced from larger coated substrates, cutting brings individual pieces to their specified dimensions after deposition. This approach can be used for precision optical filters, allowing multiple parts to be prepared from a common coated blank.
Cutting and subsequent handling take account of edge chipping, coating damage, and the clear aperture required in the finished part.
Coating Performance
A coated surface can transmit more light, reflect a selected wavelength band, or reject unwanted wavelengths according to its design. For optical windows, anti-reflection coatings reduce surface reflections at the operating wavelength and limit unwanted return light.
The coated and uncoated samples illustrate the change in appearance; spectral measurements establish the actual reflection and transmission performance.
Coating Specifications
| Parameter | Typical Capability |
|---|---|
| Coating Types | Anti-reflection, metallic reflective, dielectric reflective, and wavelength-selective coatings |
| Broadband AR Coating | Ravg ≤0.5% per surface @ 425–675 nm, 0° AOI |
| Protected Aluminum | Ravg ≥85% @ 400–700 nm |
| Protected Silver | Ravg ≥98% @ 450–800 nm |
| Protected Gold | Ravg ≥96% @ 700–2000 nm |
| Dielectric Reflective Coating | Ravg ≥99% over the specified design band |
| Bandpass Filter Transmission | Tavg ≥90% over the specified passband |
| Bandpass Filter Bandwidth (FWHM) | 10, 25, or 50 nm options |
| Out-of-Band Blocking | OD ≥4 over a specified blocking range |
| Design Angle of Incidence | 0° or 45°, depending on coating design |
| Polarization Requirements | S, P, or unpolarized light, as specified |
Have an Optical Component Drawing?
Send us your drawing or specifications. Strahl Optics will review the material, geometry, and tolerances to confirm a suitable fabrication approach for your project.