Opto Diode designs and manufactures custom EUV filters and thin-film optical coatings at its wafer-fabrication and coating facility in Camarillo, California. These filters isolate the exact wavelength band a measurement needs — most often 13.5 nm for EUV lithography or the 1–80 nm soft X-ray range — and can be deposited directly onto a photodiode or supplied as standalone components for lithography, metrology, defense, and biomedical systems.
Related detectors: SXUV EUV photodiodes and AXUV soft X-ray detectors, both available with optional integrated thin-film filters.
What is a custom EUV filter?
A custom EUV filter is a precision thin-film coating engineered to transmit a target extreme-ultraviolet or soft X-ray band while rejecting everything outside it. Because extreme wavelengths are absorbed by almost every material, the coating stack must be tuned to a specific application. A well-designed filter does three things:
- Delivers high transmission within the desired wavelength band
- Blocks out-of-band light to cut background noise and improve measurement accuracy
- Integrates directly onto an EUV photodiode, or works as a standalone component in lithography, metrology, and research systems
Wavelengths and materials
Opto Diode’s coatings span from the EUV and soft X-ray region through the visible and into the infrared. Each filter is built from the material set best suited to its band:
| Material | Typical role |
|---|---|
| Thin-film metal / silicon coatings | EUV and soft X-ray band isolation — e.g. 13.5 nm lithography monitoring |
| Sapphire | Durable UV-to-visible windows for harsh environments |
| Germanium (longpass) | Infrared cut-on filtering — e.g. 2.4 µm longpass |
| Silicon (bandpass) | Mid-infrared band selection — e.g. 4.7 µm bandpass |
| Calcium fluoride (CaF₂) | Broadband transmission from the UV into the infrared |
Filters built into the detector
The most compact option is a filter deposited directly onto the photodiode, so the detector arrives spectrally conditioned and ready to drop into an instrument. Opto Diode supplies integrated thin-film-filter parts including the SXUV100TF135 for 13.5 nm EUV monitoring and the AXUV100TF030 and AXUV100TF400 filtered soft X-ray detectors. Building the filter into the detector removes an alignment and sourcing step from your design and keeps the optical path short — see the EUV 13.5 nm power & dose monitoring guide for how this is used in practice.
Why source filters and detectors from one manufacturer
- US-based manufacturing. Wafer fabrication and thin-film coating happen in the same Camarillo, California facility. Components are ITAR-registered and hermetically sealed for demanding environments.
- Detector and filter, matched. Because Opto Diode makes both the photodiode and the coating, the responsivity curve and the filter passband are specified together rather than sourced separately and reconciled later.
- Application-specific design. Whether the goal is EUV lithography power monitoring, infrared gas sensing, or multi-wavelength biomedical detection, the coating is tuned to the measurement to raise in-band sensitivity and suppress background.
Where custom coatings are used
| Industry | Role of the filter / coating |
|---|---|
| Semiconductor lithography & soft X-ray metrology | Isolate 13.5 nm and soft X-ray bands for precise process monitoring |
| Defense & aerospace | Night-vision and infrared illumination and sensing |
| Biomedical & analytical instrumentation | Wavelength selection for diagnostics and life-science measurement |
| Environmental & industrial sensing | Long-term optical stability for gas, flame, and process monitoring |
Frequently Asked Questions
What wavelengths do Opto Diode EUV filters target?
Most commonly 13.5 nm for semiconductor EUV lithography and the 1–80 nm soft X-ray range for beamline and synchrotron metrology. Custom coatings also extend through the UV, visible, and infrared.
Can a filter be integrated directly onto a photodiode?
Yes. Thin-film filters can be deposited onto the detector itself — for example the SXUV100TF135 (13.5 nm) and the AXUV100TF030 and AXUV100TF400 — so the detector arrives spectrally conditioned with no separate filter to align.
Are the filters made in the USA and ITAR compliant?
Yes. Wafer fabrication and thin-film coating are done at Opto Diode’s Camarillo, California facility. Components are ITAR-registered and can be supplied hermetically sealed.
What materials are used in the coatings?
Depending on the band, filters combine thin-film metal and silicon coatings with substrates such as sapphire, germanium, silicon, and calcium fluoride (CaF₂), each chosen for the target wavelength and operating environment.
Discuss a custom filter or coating
Opto Diode, a division of ITW (Illinois Tool Works), brings decades of photonics manufacturing to custom EUV filters, thin-film coatings, and the detectors they pair with. To specify a filter for your application, contact our team for a tailored consultation or download the product catalog.
Reviewed and updated July 2026.
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