Ultrathin protective coatings by atomic layer engineering for far ultraviolet aluminum mirrors

Hennessy, John; Jewell, April D.; Moore, Christopher S.; Carver, Alexander G.; Balasubramanian, Kunjithapatham; Nikzad, Shouleh

doi:10.1117/12.2314185

Cited by 3 publications

(1 citation statement)

References 17 publications

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“…To protect the LiF layer, we apply a layer of MgF 2 via atomic layer deposition (ALD) using techniques developed at NASA's Jet Propulsion Lab (JPL). 11,12 This layer provides protection from moisture exposure and vastly reduces the risk of coating degradation due to prolonged exposure to water vapor. [13][14][15] With four reflections in the SPRITE primary science channel design and a requirement to deliver the CubeSat to the launch service provider up to two months before launch, this protective coating is essential to supporting the sensitivity of the SPRITE instrument.…”

Section: Uv Technology Developmentmentioning

confidence: 99%

Status and mission operations of the SPRITE 12U CubeSat: a probe of star formation feedback from stellar to galactic scales with far-UV imaging spectroscopy

Indahl,

Fleming,

Vorobiev

et al. 2023

UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XXIII

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The SPRITE (The Supernova remnants, Proxies for ReIonization Testbed Experiment ) 12U CubeSat mission, funded by NASA and led by the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder, will house the first Far-UV (100-175 nm) long-slit spectrograph with access to the Lyman UV (λ < 115 nm) and sub-arcminute imaging resolution. SPRITE will map the high energy emission from diffuse gas allowing for the study of star formation feedback in a critical, but rarely studied, Far-UV regime on both stellar and galactic scales. This novel capability is enabled by new UV technologies incorporated into SPRITE's design. These technologies include more robust, high broadband reflectivity mirror coatings and an ultra-low background photon counting microchannel plate detector. The SPRITE science mission includes weekly calibration observations to characterize the performance of these key UV technologies over time, increasing their technology readiness level (TRL) to 7+ and providing flight heritage essential for future UV flagship space missions such as the Habitable Worlds Observatory (HWO). Currently, SPRITE is in the beginning stages of integration and testing of its flight assembly with a planned delivery date of fall of 2024. This proceeding will overview the current mission status, the schedule for testing and integration prior to launch, and the planned mission operations for SPRITE.

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Section: Uv Technology Developmentmentioning

confidence: 99%

Status and mission operations of the SPRITE 12U CubeSat: a probe of star formation feedback from stellar to galactic scales with far-UV imaging spectroscopy

Indahl,

Fleming,

Vorobiev

et al. 2023

UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XXIII

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Pinholes in Al/MgF₂

et al. 2023

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Pinholes in Al/MgF2 were first inferred by the transmittance enhancement in Larruquert group’s research. However, no direct proof was reported to verify the existence of the pinholes in Al/MgF2. In the past 80 years, pinholes were first observed by dark-field microscopy and bright-field microscopy in the transmission mode. They were small and on the order of several hundred nanometers to several micrometers. Essentially, the pinhole was not a real hole, partially because of the lack of the Al element. Increasing the thickness of Al cannot reduce the size of the pinholes. The occurrence of the pinholes was dependent on the deposition rate of the Al film and the substrate heating temperature, and it was independent of the substrate materials. This research eliminates an otherwise easily ignored scattering source, and it will benefit the development of ultra-precise optics, including mirrors for gyro-lasers, the detection of gravitational waves, and coronagraph detection.

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Room temperature plasma-etching and surface passivation of far-ultraviolet Al mirrors using electron beam generated plasmas

Marcos

Boris

Gray

et al. 2021

Opt. Mater. Express

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The development of optical systems operating in the far ultraviolet range (FUV, λ=100-200 nm) is limited by the efficiency of passivated aluminum (Al) mirrors. Although it is presently possible to obtain high-reflectivity FUV mirrors through physical vapor deposition, the process involves deposition with substrates at high temperatures, which is technically challenging for large optical elements. A novel passivation procedure for bare Al mirrors is reported. The treatment consisted of using a low-temperature electron-beam generated plasma produced in a gas mixture of Ar and SF6 to etch away the native oxide layer from the Al film, while simultaneously promoting the generation of a thin aluminum tri-fluoride (AlF3) layer on the Al surface. In the first section we analyze the effect of varying both ion energy and SF6 concentration on the FUV reflectance, thickness, composition, and surface morphology of the resulting AlF3 protective layers. In the second section, the reflectivity of samples is optimized at selected important FUV wavelengths for astronomical observations. Notably, samples attained state-of-the-art reflectances of 75% at 108.5 nm (He Lyman γ), 91% at 121.6 nm (H Lyman α), 90% at 130.4 nm (OI), and of 95% at 155.0 nm (C IV). The stability over time of these passivated mirrors is also investigated.

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Ultrathin protective coatings by atomic layer engineering for far ultraviolet aluminum mirrors

Cited by 3 publications

References 17 publications

Status and mission operations of the SPRITE 12U CubeSat: a probe of star formation feedback from stellar to galactic scales with far-UV imaging spectroscopy

Status and mission operations of the SPRITE 12U CubeSat: a probe of star formation feedback from stellar to galactic scales with far-UV imaging spectroscopy

Pinholes in Al/MgF₂

Room temperature plasma-etching and surface passivation of far-ultraviolet Al mirrors using electron beam generated plasmas

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