When it comes to precision optical components for high-power laser applications, standard optical coatings do not offer sufficient durability. Specialized optical coatings are required.
At Blue Ridge Optics, we are experts in the development and of custom optical coatings for high-power laser systems.
Particulates and residual contamination from polishing and cleaning can cause unwanted laser energy absorption and compromise optical performance. In high-power laser applications, maintaining rigorous process control at every stage – from substrate preparation through final packaging – is essential to minimizing absorption and protecting the optic.
Substrates for high-power applications typically require raw materials with very low absorption, super-polished surfaces with sub-angstrom RMS roughness, surface quality better than , and reflected or transmitted wavefront quality better than .
Maintaining a clean coating chamber, selecting the right thin-film materials, and tightly controlling deposition parameters are all critical to the manufacture of high-power laser optics. Blue Ridge Optics carefully manages contamination throughout the coating process, including the control of nodules and other defects that can form on optical surfaces during deposition.
Our ISO Class 5 cleanrooms are used for final assembly, cleaning, and packaging to help minimize the risk of recontamination and preserve optical performance.
Blue Ridge Optics develops optical coatings for laser systems that must perform within highly specific wavelength ranges and under highly demanding power conditions. We have deep expertise in coating solutions for both high-power continuous-wave and high-power pulsed laser applications. Continuous-wave lasers can create sustained thermal loads that may overheat or melt an optical coating, while short-pulse lasers generate intense electromagnetic fields that can damage optical surfaces.
Our high-reflective mirror coatings are constructed from alternating layers of high-index and low-index materials, designed to deliver high reflectivity and strong laser durability. For high-power laser coatings, material selection is critical, and we often use dielectric metal oxides because of their low absorption characteristics. Silicon dioxide is commonly used for low-index layers, while high-index materials are selected based on the application and may include titanium oxide, zirconium oxide, scandium oxide, and others.
Producing high-power laser coatings requires precise control of many process parameters. Deposition rate, substrate temperature, oxygen partial pressure, thickness calibration, material melt preconditioning, and electron-beam sweep patterns all play an important role in coating performance and durability.
For example, poor control of the evaporation process can increase scatter and lead to particulate condensation on the substrate surface or within the coating itself. Because many materials used in high-power optical coatings are difficult to deposit uniformly, achieving a smooth, consistent film requires careful process control, including optimized electron-beam sweeping to support a high laser-damage threshold.
LIDT thresholds can be increased during the coating process. At Blue Ridge Optics, we use dual-monitored, Electron Beam deposition technology when creating our coatings for high-power laser optics. In combination with Ion-Assisted Deposition (IAD) and Advanced Plasma Assist (APA), E-Beam enables more concentrated coatings with properties that produce more compact thin film layers that lessen water absorption.
At Blue Ridge Optics, we have a number of tests used to determine the quality of optical coatings. Two methods for testing optical coatings for their ability to withstand laser damage are Damage Threshold Testing and Durability Certification.
Damage Threshold Testing: This process tests for failure. Irradiating the surface with a laser, we continue to increase output until the component is damaged.
Durability Certification: This is done according to precise specifications and testing parameters. These parameters might include pulse rate, pulse duration, pulse count, irradiance, and beam diameter.
Thin-film coating design requires precise test parameters to accurately evaluate the laser-induced damage threshold of optical components. At Blue Ridge Optics, our pulsed high-power laser optics undergo rigorous Laser-Induced Damage Threshold ( testing to verify performance under demanding operating conditions.
Key testing parameters and beam characteristics include wavelength, pulse duration, temporal pulse shape, beam size, waist and focus, spatial intensity distribution, repetition rate, angle of incidence, polarization, and mode of operation.
We also look at beam characteristics. These include:
At Blue Ridge Optics, we pay close attention to the characteristics of our optical coatings as they relate to their intended irradiation sources. High-powered laser applications can easily lead to coating failure due to absorption or plasma burn.
Featured Industrial Use Case
Pentagon research into continuous-wave lasers that utilize low-power, high-energy beams has gradually given way to an interest in ultrashort pulse lasers (USPLs), which are high-powered beams fired in fractions of a second to potentially vaporize an enemy target.
Direct energy optics require high-precision super-polished optics paired with highly durable low-absorption thin film coatings calibrated to exact wavelengths.
Blue Ridge Optics’ coatings have been deployed in the following defense applications:
The designers at Blue Ridge Optics have decades of experience developing high-power optical coatings for
Aerospace, Military and Defense Industries, and R&D.
