&lt;title&gt;Temperature-Invariant And Other Narrow-Band IR Filters Containing PbTe, 4-20μm&lt;/title&gt;

Seeley, J. S.; Hunneman, Roger; Whatley, A.

doi:10.1117/12.959359

Cited by 9 publications

(11 citation statements)

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“…We have investigated the degree to which such errors affect the wavelength displacement with temperature. Figure 13 shows simulated temperature variations of the bandpass transmission profile of a PbTe/ZnSe bandpass filter without thickness error, together with the same multilayer design but containing thickness errors introduced to the center cavity, particularly as this is known to be a dominating layer which is most sensitive to deviations [8]. No consequence was found of thickness errors on the wavelength displacement with temperature, even for gross thickness errors added to the most sensitive cavity layers.…”

Section: Layer Thickness Errorsmentioning

confidence: 98%

“…(2) by choice of multilayer design adds up to zero. This is the approach pursued by Seeley [8] and Li [11], as well as in this work. The enabling material is PbTe because of its negative change in refractive index (dn/dT<0) with increasing temperature.…”

Section: Temperature-dependence Theorymentioning

confidence: 99%

“…Mathematically demonstrated by Baumeister [18], the impact of a change in optical thickness of a single layer depends on the position inside the multilayer stack. The method was applied by Seeley [8] to determine; i) the cavity layer in a Fabry-Perot bandpass filter is significantly more sensitive to thickness changes than the surrounding layers, ii) a double half-wave cavity is twice as sensitive to thickness changes as a single half-wave cavity, and iii) the reflector layers adjacent to the cavity are three times more sensitive than the successive inter-cavity layers. According to these findings, the order of the filter should have major influence on the temperature response of the bandpass, as confirmed and demonstrated by the spectral measurement data presented in Section 8.…”

Section: Temperature-dependence Theorymentioning

confidence: 99%

“…The red curves show the resultant net bandpass wavelength displacement across the 20-160 ᵒC temperature range. The application of temperature-invariant properties to infrared narrow bandpass filter design has been known for a number of decades, particularly with PbTe and ZnS paired materials discussed and demonstrated formerly for Fabry-Perot (FP) single-cavity and twocavity Double Half-Wave (DHW) designs [8,11]. However, a systematic investigation of the design dependence of contemporary temperature-invariant three-cavity Triple Half-Wave (THW) filters has never been presented, and the rationale of temperature-invariant properties has remained undisclosed.…”

Section: Introductionmentioning

confidence: 99%

“…It is an extraordinary material for the following reasons [8]; the high refractive index when used with an appropriate lowindex dielectric results in one of the highest practical known index contrasts (n H /n L ) to achieve a prescribed spectral filtering function with the minimum number of layers and maximize throughput. The refractive index is one of the highest known of usable infrared layer materials with values of n ~5.5 at 300K rising to ~6.0 at 80K, (i.e.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Layer Thickness Errorsmentioning

confidence: 98%

Section: Temperature-dependence Theorymentioning

confidence: 99%

Section: Temperature-dependence Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Stolberg-Rohr¹,

Hawkins²

2015

Opt. Express

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Cooled optical filters forQ-band infrared astronomy (15-40 μm)

et al. 2016

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With a growing interest in mid-and far-infrared astronomy using cooled imaging and spectrometer instruments in highaltitude observatories and spaceflight telescopes, it is becoming increasingly important to characterise and assess the spectral performance of cooled multilayer filters across the Q-band atmospheric window. This region contains spectral features emitted by many astrophysical phenomena and objects fundamental to circumstellar and planetary formation theories. However extending interference filtering to isolate radiation at progressively longer wavelengths and improve photometric accuracy is an area of ongoing and challenging thin-film research. We have successfully fabricated cooled bandpass and edge filters with high durability for operation across the 15-30 μm Q-band region. In this paper we describe the rationale for selection of optical materials and properties of fabricated thin-film coatings for this region, together with FTIR spectral measurements and assessment of environmental durability.

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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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<title>Temperature-Invariant And Other Narrow-Band IR Filters Containing PbTe, 4-20μm</title>

Cited by 9 publications

References 0 publications

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

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

Cooled optical filters forQ-band infrared astronomy (15-40 μm)

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

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