Stresses Developed in Optical Film Coatings

Ennos, A. E.

doi:10.1364/ao.5.000051

Cited by 200 publications

(47 citation statements)

References 4 publications

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“…An initial increase and the saturation of Dd=d with the film thickness observed in Fig. 2 agrees well with a similar trend for ZnS and CdTe films on silica substrates [9]. In the same report MgF 2 and CeF 3 also exhibit similar behavior.…”

Section: Resultssupporting

confidence: 86%

Residual Stress Dependent Optical Properties of ZnI2 Films

Tyagi

Vedeshwar

2002

phys. stat. sol. (a)

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The optical absorption measurements are reported for stoichiometic, tetragonally structured ZnI 2 films. The optical band gap was found to be of the direct type. Structural analysis shows a random orientation of crystallites and the presence of internal residual stress in the film. Non-uniform compressive residual stress shows an initial increase followed by saturation with film thickness and a linear increase with treatment temperature. Both these behaviors correlate well with the variation of packing density and size distribution of crystallites as a function of film thickness and treatment temperature as seen by morphological studies. The decreasing optical band gap (E g ) with either film thickness or treatment temperature can be explained by residual compressive stress. The thickness and treatment temperature data dependences together show quite a good linear relationship between E g and the residual stress yielding a band gap of 4.75 eV for a stress free perfect crystal.

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Section: Resultssupporting

confidence: 86%

Residual Stress Dependent Optical Properties of ZnI2 Films

Tyagi

Vedeshwar

2002

phys. stat. sol. (a)

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“…Fig. 4 shows the relationship between the Cr film thickness and the internal stress determined by Ennos [10], together with our data, which qualitatively correspond to the former. Our experimental results show that Cr f'tim 68nm thick exhibits an internal tensile stress of 863 MNm -2 , which is the same order as the difference between the measured and calculated strengths in Fig.…”

Section: Methodssupporting

confidence: 82%

“…To explain this discrepancy, the internal stress in as-deposited Cr film was estimated, because Ennos [10] reported that the vacuum-deposited Cr film possesses a high internal tensile stress. The *Corning No.…”

Section: Methodsmentioning

confidence: 99%

Strength of glass with vacuum-deposited metal films: Cr, Al, Au and Ag

1980

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Fracture strength of acid-etched glass with vacuum deposited metal films is investigated. The strength of the etched glass having an initial value of 1696 + 39 MN m -2 reduces to 265 + 10MN m -2 with 69nm thick Cr film coating. AI film coating also causes the strength reduction, but the reproducibility of the strength is not found even under strictly controlled evaporation conditions. In ambient air, the strength of Au-and Agcoated glasses maintains the initial high strength value and slightly increases with film thickness. From strength reduction behaviour of Cr-coated glass and dynamic fatigue characteristics for Ag-coated glass, it is highly probable that rupture of the metal film takes place before fracture of the glass occurs, and the flaw formed in the film propagates under loading into the glass to act as a Griffith crack.

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“…The former is minimized by avoiding any color-dependent optical elements. For the latter, mechanical stress (specific to coating process), aging, and lightinduced damage (mostly from high power lasers) are known to alter the reflectance of the mirror over time (Ennos 1966;de Denus-Baillargeon et al 2014). With an FP housed in a thermally controlled evacuated chamber, we believe dispersion vari-A&A proofs: manuscript no.…”

Section: The Fpi Transmission Spectrummentioning

confidence: 99%

A laser-lock concept to reach cm s^-1-precision in Doppler experiments with Fabry-Pérot wavelength calibrators

Reiners¹,

Banyal²,

Ulbrich

2014

A&A

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State-of-the-art Doppler experiments require wavelength calibration with precision at the cm s −1 level. A low-finesse Fabry-Pérot interferometer (FPI) can provide a wavelength comb with a very large bandwidth as required for astronomical experiments, but unavoidable spectral drifts are difficult to control. Instead of actively controlling the FPI cavity, we propose to passively stabilize the interferometer and track the time-dependent cavity length drift externally using the 87 Rb D 2 atomic line. A dual-finesse cavity allows drift tracking during observation. In the low-finesse spectral range, the cavity provides a comb transmission spectrum tailored to the astronomical spectrograph. The drift of the cavity length is monitored in the high-finesse range relative to an external standard: a single narrow transmission peak is locked to an external cavity diode laser and compared to an atomic frequency from a Doppler-free transition. Following standard locking schemes, tracking at sub-mm s −1 precision can be achieved. This is several orders of magnitude better than currently planned high-precision Doppler experiments, and it allows freedom for relaxed designs including the use of a single-finesse interferometer under certain conditions. All components for the proposed setup are readily available, rendering this approach particularly interesting for upcoming Doppler experiments. We also show that the large number of interference modes used in an astronomical FPI allows us to unambiguously identify the interference mode of each FPI transmission peak defining its absolute wavelength solution. The accuracy reached in each resonance with the laser concept is then defined by the cavity length that is determined from the one locked peak and by the group velocity dispersion. The latter can vary by several 100 m s −1 over the relevant frequency range and severely limits the accuracy of individual peak locations, although their interference modes are known. A potential way to determine the absolute peak positions is to externally measure the frequency of each individual peak with a laser frequency comb (LFC). Thus, the concept of laser-locked FPIs may be useful for applying the absolute accuracy of an LFC to astronomical spectrographs without the need for an LFC at the observatory.

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Stresses Developed in Optical Film Coatings

Cited by 200 publications

References 4 publications

Residual Stress Dependent Optical Properties of ZnI2 Films

Residual Stress Dependent Optical Properties of ZnI2 Films

Strength of glass with vacuum-deposited metal films: Cr, Al, Au and Ag

A laser-lock concept to reach cm s^-1-precision in Doppler experiments with Fabry-Pérot wavelength calibrators

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Stresses Developed in Optical Film Coatings

Cited by 200 publications

References 4 publications

Residual Stress Dependent Optical Properties of ZnI2 Films

Residual Stress Dependent Optical Properties of ZnI2 Films

Strength of glass with vacuum-deposited metal films: Cr, Al, Au and Ag

A laser-lock concept to reach cm s-1-precision in Doppler experiments with Fabry-Pérot wavelength calibrators

Contact Info

Product

Resources

About

A laser-lock concept to reach cm s^-1-precision in Doppler experiments with Fabry-Pérot wavelength calibrators