Comparison of algorithms used for optical characterization of multilayer optical coatings

Amotchkina, Tatiana V.; Trubetskov, Michael K.; Pervak, Vladimir; Schlichting, S.; Ehlers, Henrik; Ristau, Detlev; Tikhonravov, Alexander V.

doi:10.1364/ao.50.003389

Cited by 29 publications

(16 citation statements)

References 18 publications

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“…Refractive indices of Ta 2 O 5 and SiO 2 thin-film materials have been found with high accuracy and verified using reliable results of the previous studies [23,24]. This allows us to neglect possible small offsets in layer refractive indices and to attribute the observed deviations to errors in layer thicknesses.…”

Section: Error Analysis and Reverse Engineering For Accurate Determinsupporting

confidence: 76%

Advantages and challenges of optical coating production with indirect monochromatic monitoring

et al. 2015

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In this paper, we present our recent studies on raising the quality of optical coating production with an indirect monochromatic monitoring system. Preproduction error analysis and computational manufacturing are used to estimate potential advantages of application of indirect optical monitoring. It is then demonstrated that a key issue for realization of this advantage is accurate specification of tooling factors for layer thicknesses on test glasses. The tooling factors are precalibrated using single layer depositions and then are corrected using results of reverse engineering for the first production run. It is found that a gradual variation of tooling factors of low index layers is the main error factor in the first deposition run. Finally, we redeposit our coating with a modified monitoring strategy, taking into account this factor. The new experimental results show excellent correspondence with the theoretical spectral performance.

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Section: Error Analysis and Reverse Engineering For Accurate Determinsupporting

confidence: 76%

Advantages and challenges of optical coating production with indirect monochromatic monitoring

et al. 2015

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“…Refractive indices of Ta 2 O 5 and SiO 2 thin-film materials have been found with a high accuracy and verified using reliable results of the previous studies [17,18]. This allows us to neglect possible small offsets in layer refractive indices and to attribute the observed deviations to errors in layer thicknesses.…”

Section: Reverse Engineering and Re-deposition With Modified Monitorisupporting

confidence: 75%

Design, production and reverse engineering of ultra-steep hot mirrors

Zhang¹,

Tikhonravov²,

Liu³

et al. 2014

Opt. Express

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Abstract:We present the whole design-production chain of an ultra-steep hot mirror produced using the indirect monochromatic monitoring technique. The hot mirror without thin layers is designed utilizing the stochastic optimization procedure that takes in account upper and lower constraints for layer optical thickness. We produced the hot mirror with the ion-assisted electron beam deposition technique using indirect monochromatic monitoring strategy, performed reverse engineering of the deposited coatings, and illustrated that the random variation of the tooling factors in low-index layers is the main factor causing production errors. We modified the monitoring strategy with low-index layers monitored by quartz crystal monitor, and demonstrated the excellent correspondence to the theoretical spectral performance.

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“…Employing a needle algorithm the subsequent layers can be optimized with respect to the specified group delay dispersion and reflection target values. An optimization cycle can be performed in situ after every coated layer [10]. Especially taking into account the extreme sensitivity of the designed GDD to deposition errors in the last layers, the conventional BBM is used for layer termination until the fifth last layer of the design is finished.…”

Section: Deposition Processmentioning

confidence: 99%

Precise fabrication of ultra violet dielectric dispersion compensating mirrors

et al. 2015

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The present contribution is concentrated on an improved method to manufacture dielectric dispersion compensating mirrors in the ultra violet (UV) range by applying a novel online phase monitoring device. This newly developed measurement tool monitors the group delay (GD) and group delay dispersion (GDD) of the electromagnetic field in situ during the deposition of the layer system. Broad band monitoring of the phase enhances the accuracy in the near infrared spectral range (NIR), significantly. In this study, the correlation of the GDD in the NIR and in the UV spectral range is investigated. A design synthesis is introduced to achieve optimum reflection and GDD target values in the UV and NIR. This requires a similar behavior of both bands according to deposition errors, to guarantee switching off the UV GDD target band proper, while monitoring the GDD in the NIR spectral range. The synthesis results in a design, characterized by a GDD of -100fs 2 ±20fs 2 between 330nm and 360nm in the UV and by -450fs 2 ±10fs 2 within 820nm to 870nm in the NIR. The fabricated sample, applying an ion beam sputtering process, consists of a 9µm layer stack of Hafnium oxide and Silicon dioxide. The first layers of the stack are switched and controlled by a conventional in situ spectrometric broad band monitoring in conjunction with a forward re-optimization algorithm, which also manipulates the layers remaining for deposition at each switching event. To accomplish the demanded GDD-spectra, the last layers are controlled by the novel in situ GDD monitor.

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Comparison of algorithms used for optical characterization of multilayer optical coatings

Cited by 29 publications

References 18 publications

Advantages and challenges of optical coating production with indirect monochromatic monitoring

Advantages and challenges of optical coating production with indirect monochromatic monitoring

Design, production and reverse engineering of ultra-steep hot mirrors

Precise fabrication of ultra violet dielectric dispersion compensating mirrors

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