Cooled optical filters for<i>Q</i>-band infrared astronomy (15-40 μm)

Hawkins, Gary; Sherwood, Richard; Djotni, Karim; Threadgold, Timothy M.

doi:10.1117/12.2231669

Cited by 3 publications

(2 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Currently, it dominates the material selection for the design of infrared thin-film interference filters operating in the long wavelength infrared both at room and reduced temperature. The combination of its high index (above 5.5 in the spectral range of long wavelength infrared at room temperature) and its advantage of a negative temperature coefficient of refractive index (À2.0 Â 10 À3 K À1 ) make it much superior to other infrared coating materials [11][12][13][14][15][16][17].…”

Section: Properties and Applications Of Pbtementioning

confidence: 99%

Infrared High-Index Coating Materials, PbTe and Pb1−xGexTe: Properties and Applications

Li¹,

Xie²,

Zhang³

et al. 2019

Coatings and Thin-Film Technologies

View full text Add to dashboard Cite

The greater value of refractive index for high-index layers in thin-film interference filters operating in the infrared has an incomparable advantage. Lead telluride (PbTe), which is much superior to other infrared high-index coating materials due to its high index and advantage of fundamental absorption edges, has played an important role in filters employed in the infrared radiometer and other instruments launched in space atmosphere sounding research projects. In this chapter, we summarized some recent achievements in the investigations into another infrared high-index coating material-lead germanium telluride (Pb 1Àx Ge x Te), a pseudo-binary alloy of PbTe and GeTe. It can be revealed that the layers of Pb 1Àx Ge x Te exhibit the tunable optical properties, such as temperature coefficient of refractive index and fundamental absorption edge, as well as mechanical properties, such as the hardness and Young's modulus, corresponding to its intrinsic ferroelectric phase transition. Some important applications in thin-film interference filters were also demonstrated for its tremendous potential, such as a stable narrow bandpass interference filter without temperature-induced wavelength shift and a tunable infrared short wavelength cutoff filter. Furthermore, it is also revealed that electron beam evaporation is a more effective congruent-transfer technique to deposit the layers of Pb 1Àx Ge x Te.

show abstract

Section: Properties and Applications Of Pbtementioning

confidence: 99%

Infrared High-Index Coating Materials, PbTe and Pb1−xGexTe: Properties and Applications

Li¹,

Xie²,

Zhang³

et al. 2019

Coatings and Thin-Film Technologies

View full text Add to dashboard Cite

show abstract

“…7 Multilayer interference filters have also been developed, for example the CdTe Q-band filter to be used as a wide bandpass filter on the Mid-infrared instrument (MIRI) of the James Webb Space Telescope (JWST). 8 BETTII (Balloon Experimental Twin Telescope for Infrared Interferometry) is a balloon-borne double-Fourier interferometer capable of Michelson interferometry and simultaneous Fourier Transform Spectroscopy in the FIR wavelengths of 30-100 µm (Figure 1). The optics of BETTII collects light from two apertures 8 meters apart and combines them, while modulating the optical path lengths to produce interferometric fringes at the FIR detectors.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and characterization of a NIR-FIR dichroic for the infrared interferometer BETTII

Dhabal

Rinehart

Silverberg

et al. 2018

Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX

View full text Add to dashboard Cite

BETTII is a balloon-borne far infra-red (FIR: 30-100 µm) interferometer that also uses a near-infrared (NIR: 1-2.5 µm) channel for fine pointing sensing using stars. We have developed an inductive grid dichroic to divide the incoming beam into two components, by reflecting FIR light and transmitting NIR light. The dichroic is fabricated using focused electron beam technology to produce a 1 µm period, 100 nm width metal grid on a sapphire substrate in order to have high reflectance for FIR wavelengths. Here we discuss the design and the detailed manufacturing process for such a dichroic. The transmission and reflectance characteristics are also presented. We discuss them in context of the BETTII requirements.

show abstract

Concept and Design of Martian Far-IR ORE Spectrometer (MIRORES)

et al. 2022

View full text Add to dashboard Cite

Sulfide ores are a major source of noble (Au, Ag, and Pt) and base (Cu, Pb, Zn, Sn, Co, Ni, etc.) metals and will, therefore, be vital for the self-sustainment of future Mars colonies. Martian meteorites are rich in sulfides, which is reflected in recent findings for surface Martian rocks analyzed by the Spirit and Curiosity rovers. However, the only high-resolution (18 m/pixel) infrared (IR) spectrometer orbiting Mars, the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), onboard the Mars Reconnaissance Orbiter (MRO), is not well-suited for detecting sulfides on the Martian surface. Spectral interference with silicates impedes sulfide detection in the 0.4–3.9 μm CRISM range. In contrast, at least three common hydrothermal sulfides on Earth and Mars (pyrite, chalcopyrite, marcasite) have prominent absorption peaks in a narrow far-IR (FIR) wavelength range of 23–28 μm. Identifying the global distribution and chemical composition of sulfide ore deposits would help in choosing useful targets for future Mars exploration missions. Therefore, we have designed a new instrument suitable for measuring sulfides in the FIR range called the Martian far-IR Ore Spectrometer (MIRORES). MIRORES will measure radiation in six narrow bands (~0.3 µm in width), including three bands centered on the sulfide absorption bands (23.2, 24.3 and 27.6 µm), two reference bands (21.5 and 26.1) and one band for clinopyroxene interference (29.0 µm). Focusing on sulfides only will make it possible to adapt the instrument size (32 × 32 × 42 cm) and mass (<10 kg) to common microsatellite requirements. The biggest challenges related to this design are: (1) the small field of view conditioned by the high resolution required for such a study (<20 m/pixel), which, in limited space, can only be achieved by the use of the Cassegrain optical system; and (2) a relatively stable measurement temperature to maintain radiometric accuracy and enable precise calibration.

show abstract

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

Cited by 3 publications

References 30 publications

Infrared High-Index Coating Materials, PbTe and Pb1−xGexTe: Properties and Applications

Infrared High-Index Coating Materials, PbTe and Pb1−xGexTe: Properties and Applications

Fabrication and characterization of a NIR-FIR dichroic for the infrared interferometer BETTII

Concept and Design of Martian Far-IR ORE Spectrometer (MIRORES)

Contact Info

Product

Resources

About