The manufacturing of precision optical components requires state of the art metrology. At Advanced Thin Films, we have developed advanced methods to measure the optical properties of our devices because measurement is fundamental to everything we do. Whether testing extinction ratio to 45dB at 1064nm (32,000:1), verifying parallelism to less than 0.1 arc seconds or actually certifying the maximum energy thresholds of our coatings, we believe that the numbers don't lie. ATF also partners with universities and national laboratories to access the most advanced measurement tools in order to provide you with the most accurate and complete information available.
Examples of some of our in-house capabilities are shown here.
Differential Interference Contrast Microscopy (DICM) Images of standard and superpolished surfaces. The method shown here is also known as Nomarski imaging—a primary tool used for characterizing sub-Angstrom surfaces.
Photothermal Common-Path Interferometry (PCI)
ATF is now using in-house PCI for absorption measurements of substrate surfaces, coatings, and bulk materials at 1070nm. This new system is a key piece of metrology for applications with critical requirements for very low absorption coatings, such as the high power continuous wave (CW) lasers used in materials processing and directed energy. ATF is also utilizing these measurements to monitor the batch-to-batch quality of our ion-beam-sputtered (IBS) optics and coatings.
Photothermal Common-Path Interferometry (PCI) is a metrology method that creates and measures a tiny, localized thermal lens with sensitivity of less than 1 part-per-million (ppm) for fractional absorption. It uses a strong pump beam to create the thermal lens effect in conjunction with a weak probe beam to detect the resulting aberration. The technique is insensitive to scatter, non-destructive, and can measure bare or coated surfaces as well as bulk material absorption of a substrate.
Actual Coating Absorption < 1 PPM
(Measured at 1070 nm using ATF's in-house PCI system)
- Total absorption at coated surface is ~1.5 ppm
- Bulk absorption corresponds to ~0.8 ppm
- Uncoated surface absorption is ~1.0 ppm
- Actual AR coating absorption is < 1 ppm