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The advent of the extensive use of Zoom and similar meeting venues has made the reflection from eyeglasses more apparent and distracting. Eyeglass lenses which have not been antireflection (AR) coated typically reflect more than 4% of light from each lens surface or more than 8% per lens. Lenses with the common 4-layer AR coating still reflect more than 0.5% of greenish or bluish light per surface. When we observe the reflection of a bright computer screen or other illumination sources in someone’s glasses while they are communicating with a video image, it is particularly distracting if they have uncoated lenses, but it still can be distracting even with the common 4-layer AR coatings. The currently available technology will allow the reduction of these reflections by an order of magnitude so that we can “look someone in the eye” when we talk with them via video conferencing. The new coatings would probably use 6-10 layers, which is not many layers as compared to more sophisticated applications where over 100 layers are now used. The common production issues limiting performance now are inadequate reproducibility of factors like pressure, rate, uniformity, temperature, etc. Tighter process control would tend to make these coatings somewhat more expensive than the present 4-layer coatings, but discerning users would probably be willing to pay a premium for their improved appearance when being viewed by video.

https://doi.org/10.14332/svc24.proc.0030

A new three-layer, with three materials, antireflection (AR) coating design has been discovered. The designs for the classic three- and four-layer AR coatings in common use, when optimized with respect to the photopic response of the eye, can reduce the luminous (Y) value of reflectance to between 0.05 and 0.08 or 0.05% to 0.08%, as compared to 4.3% for uncoated crown glass. This invention can further reduce this to 0.02%. The classical three-layer AR design employs successive layers on the glass substrate of: medium, high, and low indices of refraction which are approximately one quarter, one half, and one quarter wavelength of optical thickness at a wavelength near the center of the visible spectrum. This discovery uses a notably different material for the second layer, and thereby reduces the photopic reflectance by a factor of 2 to 4 times. The performance depends a great deal on the detail index of refraction properties of this material.

https://doi.org/10.14332/svc24.proc.0031

sensors, and spatial light modulators. In this work, multilayer metallo-dielectric (MD) induced transmission filters composed of alternating layers of dielectric silicon nitride (Si₃N₄) and metal (M = Ag, Au, or Al) films were designed using dispersion relations for infinite multilayer metallo-dielectric structures according to the formulation: Si₃N₄) (d₁/2)[M(d₂)| Si₃N₄) (d₁)]3M(d₂)| Si₃N₄) (d₁/2), where d₁ represents the thickness of the internal dielectric layer. The 9-layer MD stacks were fabricated on 2-inch diameter fused silica substrates via pulsed DC magnetron sputtering (PDCMS) in Ar for M film growth and reactive PDCMS in an Ar/N₂ mixture for Si₃N₄) film growth. The optical constants and layer thicknesses of thin film Ag, Au, Al, and Si₃N₄) were monitored in real time during the PDCMS processes using in situ spectroscopic ellipsometry. In our MD designs, Si₃N₄ was selected (over conventional low-index dielectric oxides) to protect the deposited metal layers from uncontrolled oxidation or oxidative diffusion during reactive PDCMS and upon subsequent ambient air exposure. Thorough analysis of the optical and structural characteristics of Si₃N₄) films, metal films, and 9-layer Si₃N₄) /M multilayer stacks is presented from ex situ spectroscopic ellipsometry, UV-Vis-NIR spectrophotometry, X-ray diffraction (XRD), and X-ray reflectivity (XRR) techniques. The optical transmission spectra of the multilayer MD stacks were also modeled using a 2x2 anisotropic transfer matrix method (TMM), developed to analyze optical propagation through uniaxial stacks and are in close agreement with the experimental transmission spectra measured from UV-Vis-NIR spectrophotometry.

https://doi.org/10.14332/svc24.proc.0028

Over the past years, increased understanding of arc behaviour during thin film deposition processes has led to improvements in plasma power supply design. This has helped significantly minimize negative effects related to arcing. In this contribution, we demonstrate the effect of different arc handling parameters available at the power supplies that can be used to tailor arcing characteristics during sputtering of insulating films. We show the effect of arc management parameters on arc energies, backed by experimental studies on silicon oxide and aluminium oxide processes performed in an industrial drum coater.
To deposit these insulating materials, different power delivery modes are available to a user such as dual magnetron bipolar mode (BP) and dynamic reverse pulsing mode (DRP). We discuss the differences between these two modes, provide an in-depth statistical study to showcase the effect of pulsing frequency on these modes, and compare them in terms of arc rates and energies.

https://doi.org/10.14332/svc24.proc.0020

The Vera C. Rubin Observatory construction is poised to be completed, finishing the Integration phase and starting the Commissioning phase. The Coating Plant is delivering the coated main science mirrors to the project. The M2 mirror was coated with protected Silver in 2019 and the M1M3 mirror coated in 2024 with protected Silver as well, both coatings achieving the main project requirements. This paper describes the main project milestones in terms of construction, assembly and integration, the coating results on both mirrors. This paper also describes a characterization of the Coating Plant and its ancillary equipment, a characterization of the coating delivered by us, the coating tests that we made prior of the final coating recipe decision, and the final coating results over the main telescope mirrors, finishing with the future projects related to this Coating System.

https://doi.org/10.14332/svc24.proc.0025

Atomic Layer Deposition (ALD) is now a well-established process broadly used in the manufacture of leading-edge semiconductor chips. ALD is required for this application due to its high level of precision and ability for conformal deposition of pinhole-free coatings on complex surfaces. These same coating attributes are highly desirable in other applications, such as thin film encapsulation, on the large area substrates used in the display and photovoltaic industries. But to date, scaling of ALD processes to such large substrates, with sufficient throughput and at the low cost required for these applications, has been elusive. In this work, a novel Spatial Plasma Enabled ALD (S-PEALD) process is demonstrated that offers the economic scalability of ALD to these large area substrates. The use of a simple DC plasma source, enabled by the use of spatial processing, allows plasma generation over the multi-meter distances required for these substrate sizes. Meanwhile, a novel method for spatial precursor separation provides the means to utilize a simple, compact, and rapidly moving coating head for executing the ALD cycle. In combination with a mixed oxide barrier material, a process is demonstrated that provides a path to the in-line deposition of OLED-quality barrier coatings on multi-meter substrates, with a takt time of less than one minute.

https://doi.org/10.14332/svc24.proc.0022

Bipolar pulsed sputter deposition provides a robust method for depositing insulating coatings like oxides and nitrides. For several years, both sine-wave and squarewave generators have been utilized for these processes. Different applications demand stringent and distinct coating requirements, and pulse mode provides an additional variable enabling a user to optimize film microstructure and thereby film properties. This presentation shows a comparative study of three types of bipolar pulsed modes: symmetric sinusoidal pulsing, symmetric square pulsing and the new asymmetric square pulsing mode called dynamic reverse pulsing. The three modes were tested on reactive sputter deposition of silicon nitride films in an industrial drum coater. The aim is to provide a comprehensive understanding of the different modes and their influence on the film properties in terms of deposition rate, heat load at the substrate, residual stress and optical properties. We show that the different pulse modes have inherent differences in plasma behavior and we outline their benefits.

https://doi.org/10.14332/svc24.proc.0024

On December 5, 2022, Ignition (gain >1) was demonstrated at the National Ignition Facility (NIF) and repeated on July 30, 2023. On the NIF there are 832 high fluence 1ω transport mirrors of which ~36 are exchanged annually due to laser damage initiated typically from debris within the beam tubes or 3ω backscatter from the target. Multiple technologies are currently used to mitigate these laser damage sources including spectral filtering, gas knives, and spot blockers. One of the contributing factors for achieving Ignition was an increase from 1.9 to 2.05 MJ of 3ω laser energy on target. New technologies are being developed to safely ramp up NIF in energy with minimal laser damage, to achieve a goal of even higher gain. For the transport mirrors, these new technologies include non-stick monolayers that would be deposited over the e-beam deposited multilayer mirrors to improve the efficiency of the gas knives at removing debris, femtosecond laser machining to arrest laser damage growth thus enabling increasing the range of laser conditioning before installation, and the substitution of alumina for hafnia as the high index material for improved 3ω laser damage resistance of the mirrors closest to the target chamber.

https://doi.org/10.14332/svc24.proc.0027

processes. Ampres has developed a new generation of scalable closed drift gas ionizers. These sources provide an economical tool for the deposition of complex high quality multilayer thin film coatings. The gas ionizers provide very high ionization rates in a compact fully scalable design. They are used to supply ionized reactive gas for enhanced magnetron sputtering processes and for a unique hybrid PVD–PECVD process.
These sources are ideally suited to deliver ionized reactive gases like Oxygen, Nitrogen and Fluorine direct to the substrate surface to form metal oxide, metal nitride and other complex thin film coatings. They also can be used as standalone plasma sources for PECVD and plasma etching applications.

https://doi.org/10.14332/svc24.proc.0023

Optical coatings for satellite communication (SatCom) applications using free-space optics (FSO) have demanding requirements for durability and spectral performance. Optical systems for SatCom require high transmission of telecommunication (telecom) bands while providing rejection of unwanted radiation from a wide band extending from UV to IR that correspond to both solar output and thermal energy from the Earth. It is critical that thermal energy from these sources entering the optical system be kept to a minimum in order to reduce the noise in both the data transmit and receive signals, as well as keep the sensitive piezo-driven mirrors within the system from experiencing thermally induced variability. Many systems utilizing polarization-multiplexing also require that optical coatings cause minimal phase retardance upon reflection or transmission. We demonstrate optical coating performance for dichroics and bandpasses used to separate telecom bands while maintaining low phase retardance over particular wavelengths. We will show spectral and phase performance for “solar filters” consisting of sputtered silver- or gold-based inducedtransmission type filters with over 90% transmission of the C-band and having high reflection of solar-Earth radiation over the full cone of angles. We will also show durability performance and discuss other applications for these coatings.

https://doi.org/10.14332/svc24.proc.0032