Infrared filters and coatings for the High Resolution Dynamics Limb Sounder (6–18 µm)

Hawkins, Gary; Hunneman, Roger; Sherwood, Richard; Barrett, Barbara

doi:10.1364/ao.39.005221

Cited by 18 publications

(11 citation statements)

References 7 publications

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“…Initial assumptions were made of the optical properties of the multi-layer materials by comparing transmission performance, shape and bandwidth of the calculations with the measurement. From these calculations the refractive index ðnÞ and extinction coefficient ðKÞ constants of the complex refractive index of the multiplayer materials [11] ZnSe (n ¼ 2:35, k ¼ 0:001), ZnS (n ¼ 2:15, k ¼ 0:001), Ge (n ¼ 3:9, k ¼ 0:003) were derived by iterative calculation modelling. Using this initial starting model, the multi-layer designs of both surfaces were introduced to a Levenberg-Marquardt optimization routine (adapted from the public-domain Argonne National Laboratory Minpack library), using the spectral transmission of the filter measured at 80 K as the target function.…”

Section: Spectral Modellingmentioning

confidence: 99%

Reversible ageing effects in cryogenically cooled infrared filter radiometers

Theocharous¹,

Hawkins²,

Fox³

2005

Infrared Physics & Technology

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Section: Spectral Modellingmentioning

confidence: 99%

Reversible ageing effects in cryogenically cooled infrared filter radiometers

Theocharous¹,

Hawkins²,

Fox³

2005

Infrared Physics & Technology

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“…This library of filters represents a wide cross-section of generic multilayer bandpass design types and wavelengths, comprising both L-and H-spaced integral thickness cavities, differing cavity thickness orders, operating temperature requirements and center wavelength positioning. Narrow bandpass filters from two missions; the NASA Aura mission High Resolution Dynamics Limb Sounder (HIRDLS) [1] and Indian Space Research Organization (ISRO) INSAT-3D [32] atmospheric sounder instruments comprised a wide range of differing bandpass designs containing 3-cavity triple half-wave (THW) low-index (L) cavity layers with differing thickness orders using alternate ZnSe and PbTe layers deposited on Germanium (Ge) optical substrates. The HIRDLS instrument bandpass filters were deployed in the focal plane detector array of this limb-viewing infrared radiometer which was designed for high resolution monitoring of global stratospheric and mesospheric temperatures and chemical species in the atmosphere at wavelengths between 6 and 18 µm.…”

Section: Comparison With Manufactured Filtersmentioning

confidence: 99%

“…However, it is generally a cause of concern to spectroscopists employing bandpass filters to discriminate between different molecular species with spectrally overlapping absorption signatures. Historically, infrared optical filters have been integrated in cooled and temperature stabilized detecting systems with working temperatures far-below the filter manufacturing conditions [1]. Therefore the filter designer has always needed to take wavelength shifts with temperature into consideration.…”

Section: Introductionmentioning

confidence: 99%

Spectral design of temperature-invariant narrow bandpass filters for the mid-infrared

Stolberg-Rohr¹,

Hawkins²

2015

Opt. Express

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Abstract:The ability of narrow bandpass filters to discriminate wavelengths between closely-separated gas absorption lines is crucial in many areas of infrared spectroscopy. As improvements to the sensitivity of infrared detectors enables operation in uncontrolled high-temperature environments, this imposes demands on the explicit bandpass design to provide temperature-invariant behavior. The unique negative temperature coefficient (dn/dT<0) of Lead-based (Pb) salts, in combination with dielectric materials enable bandpass filters with exclusive immunity to shifts in wavelength with temperature. This paper presents the results of an investigation into the interdependence between multilayer bandpass design and optical materials together with a review on invariance at elevated temperatures. ©2015 Optical Society of America

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“…As far as the infrared interference filters employed in the spaceborne remote sensing systems are concerned, as a rule, the materials are lead telluride (PbTe) for high-index layers, and either zinc sulphide (ZnS) or zinc selenide (ZnSe) for low-index layers 3,4 . All materials are fully transparent over the infrared.…”

Section: Intruductionmentioning

confidence: 99%

New advances in improving low-temperature stability of infrared thin-film interference filters

Zhang

Liu

et al. 2005

SPIE Proceedings

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The degeneration of performance of an optical thin-film interference filter associated with the change of temperature is not acceptable. In this letter, we report a new progress in improving low-temperature performance of infrared narrow-band filters by using Pb 1-x Ge x Te initial bulk alloy with appropriate Ge concentration x. It can be found that there exists a critical temperature for the investigated narrow-band filter, at which the temperature coefficient of filter is exactly zero. Therefore, by means of controlling the composition in (Pb 1-x Ge x ) 1-y Te y layers, the temperature coefficient of filter can be tunable at the designated low-temperature. In our present investigation, when temperature varies from 300 to 85 K, a shift of peak wavelength of 0.05935 nm.K -1 has been achieved. INTRUDUCTIONThe performance of an optical thin-film interference filter can be influenced by the change of ambient temperature.The peak or cut-off wavelength will shift and the pass-band shape and peak transmission will deteriorate due to the effects of varying temperatures. In particular, when the filter is used in light-wave communication systems or spaceborne remote sensing instruments, the degeneration of performance is not acceptable. It becomes difficult to sustain the functional performance of non-dispersive narrow-band interference filters for precision spectroradiometric measurements from space 1 . It is not practical to add an auxiliary temperature control to a narrow-band filter in order to maintain its stable optical performance in spaceborne remote sensing systems.There are two factors that cause the instability of the performance of a thin-film interference filter accompanied by the change of temperature: one is the temperature-induced variations in the indices of refraction of layers; another is the variations in the physical thicknesses of layers. Since the bulk temperature coefficients of linear expansion are an order of magnitude smaller than the temperature coefficients of refractive index for substances employed for interference filters, it may be speculated that the shift of wavelength should be ascribed to the variations of temperature coefficients of indices of layers 2 .By classical design, optical interference filters typically consist of multiple homogeneous layers of two materials with low and high refractive indices. As far as the infrared interference filters employed in the spaceborne remote sensing systems are concerned, as a rule, the materials are lead telluride (PbTe) for high-index layers, and either zinc

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Infrared filters and coatings for the High Resolution Dynamics Limb Sounder (6–18 µm)

Cited by 18 publications

References 7 publications

Reversible ageing effects in cryogenically cooled infrared filter radiometers

Reversible ageing effects in cryogenically cooled infrared filter radiometers

Spectral design of temperature-invariant narrow bandpass filters for the mid-infrared

New advances in improving low-temperature stability of infrared thin-film interference filters

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