Mr. Thomas D. Rahmlow Profile

Thomas D. Rahmlow

Senior Scientist at Omega Optical Inc

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Publications (20)

Proceedings Article | 13 June 2022 Presentation

Single and dual band linear variable filters (LVF) for the mid and far infrared

Thomas Rahmlow, Terrance Finnell, Timothy Olsen, Robert Johnson

Proceedings Volume PC12103, PC1210304 (2022) https://doi.org/10.1117/12.2618975

KEYWORDS: Optical filters, Linear filtering, Imaging systems, Far infrared, Bandpass filters, Image filtering, Hyperspectral imaging, Coating, Stray light, Spectroscopy

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Proceedings Article | 30 May 2022 Presentation

Spectral control options for thermophotovoltaic recovery of waste heat

Thomas Rahmlow

Proceedings Volume PC12090, PC1209002 (2022) https://doi.org/10.1117/12.2618968

KEYWORDS: Photons, Control systems, Optical filters, Near infrared, Radioisotopes, Manufacturing, Glasses, Black bodies

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Proceedings Article | 2 March 2020 Paper

Stable and tunable performance of ultra-narrow bandpass and high edge slope dichroic optical filters

Markus Fredell, Thomas Rahmlow, William Cote, Robert Mann, Robert Johnson

Proceedings Volume 11272, 112721F (2020) https://doi.org/10.1117/12.2547866

KEYWORDS: Optical filters, Bandpass filters, Oxides, Temperature metrology, Thin films, Refractive index

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Proceedings Article | 2 March 2020 Presentation + Paper

Hyperspectral imaging using a Linear Variable Filter (LVF) based ultra-compact camera

Thomas Rahmlow, William Cote, Robert Johnson

Proceedings Volume 11287, 1128715 (2020) https://doi.org/10.1117/12.2546709

KEYWORDS: Cameras, Optical filters, Image filtering, Linear filtering, Sensors, Bandpass filters, Spectroscopy, Hyperspectral imaging, Imaging systems, Spatial resolution

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Proceedings Article | 13 May 2019 Presentation + Paper

Advanced window coatings for drone and ground based applications

Terrance Finnell, Markus Fredell, Gregg Jarvis, Ian Barrett, Robert Sczupak, Scott Cohen, Thomas Rahmlow, Robert Mann, Robert Johnson

Proceedings Volume 10985, 109850C (2019) https://doi.org/10.1117/12.2519127

KEYWORDS: Sensors, Optical filters, Thin film coatings, Oxides, Near infrared, Electromagnetic coupling, Visible radiation, Optical coatings, Reflection, Photography

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Proceedings Article | 22 February 2018 Presentation + Paper

Measurement and alignment of linear variable filters

Rob Sczupak, Markus Fredell, Tim Upton, Tom Rahmlow, Sheetal Chanda, Gregg Jarvis, Sarah Locknar, Florin Grosu, Terry Finnell, Robert Johnson

Proceedings Volume 10539, 105390Y (2018) https://doi.org/10.1117/12.2290689

KEYWORDS: Optical filters, Linear filtering, Sensors, Calibration, Collimation, Image filtering, Optical design, Optical alignment

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Proceedings Article | 15 February 2018 Presentation + Paper

Ultra-narrow bandpass optical interference filters for deep space optical communication

Thomas Rahmlow, Timothy Upton, Markus Fredell, Terrance Finnell, Stephen Washkevich, Kirk Winchester, Tina Hoppock, Robert Johnson

Proceedings Volume 10524, 1052416 (2018) https://doi.org/10.1117/12.2290753

KEYWORDS: Bandpass filters, Optical filters, Annealing, Optical communications, Monte Carlo methods, Interference filters, Manufacturing

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Proceedings Article | 7 June 2017 Presentation

Linear variable narrow bandpass optical filters in the far infrared (Conference Presentation)

Thomas Rahmlow

Proceedings Volume 10181, 101810L (2017) https://doi.org/10.1117/12.2266147

KEYWORDS: Optical filters, Linear filtering, Sensors, Image filtering, Spectroscopy, Far infrared, Hyperspectral systems, Infrared radiation, Antireflective coatings, Absorbance

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We are currently developing linear variable filters (LVF) with very high wavelength gradients. In the visible, these filters have a wavelength gradient of 50 to 100 nm/mm. In the infrared, the wavelength gradient covers the range of 500 to 900 microns/mm. Filter designs include band pass, long pass and ulta-high performance anti-reflection coatings. The active area of the filters is on the order of 5 to 30 mm along the wavelength gradient and up to 30 mm in the orthogonal, constant wavelength direction. Variation in performance along the constant direction is less than 1%. Repeatable performance from filter to filter, absolute placement of the filter relative to a substrate fiducial and, high in-band transmission across the full spectral band is demonstrated. Applications include order sorting filters, direct replacement of the spectrometer and hyper-spectral imaging. Off-band rejection with an optical density of greater than 3 allows use of the filter as an order sorting filter. The linear variable order sorting filters replaces other filter types such as block filters. The disadvantage of block filters is the loss of pixels due to the transition between filter blocks. The LVF is a continuous gradient without a discrete transition between filter wavelength regions. If the LVF is designed as a narrow band pass filter, it can be used in place of a spectrometer thus reducing overall sensor weight and cost while improving the robustness of the sensor. By controlling the orthogonal performance (smile) the LVF can be sized to the dimensions of the detector. When imaging on to a 2 dimensional array and operating the sensor in a push broom configuration, the LVF spectrometer performs as a hyper-spectral imager. This paper presents performance of LVF fabricated in the far infrared on substrates sized to available detectors. The impact of spot size, F-number and filter characterization are presented. Results are also compared to extended visible LVF filters.

Proceedings Article | 17 May 2016 Paper

Ultra-narrow bandpass filters for infrared applications with improved angle of incidence performance

Thomas Rahmlow, Markus Fredell, Sheetal Chanda, Robert Johnson

Proceedings Volume 9822, 982211 (2016) https://doi.org/10.1117/12.2225113

KEYWORDS: Optical filters, Bandpass filters, Infrared radiation, Electronic filtering, Dental caries, Signal to noise ratio, Temperature metrology, Oxides, Free space optics, Interference filters

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Proceedings Article | 3 March 2016 Paper

Gas sensors using single layer patterned interference optical filters

Thomas Rahmlow, Kieran Gallagher, Robert Johnson

Proceedings Volume 9751, 97510Z (2016) https://doi.org/10.1117/12.2213494

KEYWORDS: Optical filters, Absorption, Sensors, Gas sensors, Fiber optics sensors, Carbon dioxide, Waveguides, Linear filtering, Refractive index, Bandpass filters

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Proceedings Article | 21 May 2011 Paper

Dual-band antireflection coatings on 3rd Gen lenses

Thomas Rahmlow, Jeanne Lazo-Wasem, Jay Vizgaitis, Justin Flanagan-Hyde

Proceedings Volume 8012, 80123D (2011) https://doi.org/10.1117/12.888100

KEYWORDS: Lenses, Germanium, Antireflective coatings, Mid-IR, Optical coatings, Neodymium, Long wavelength infrared, Infrared imaging, Infrared radiation, FT-IR spectroscopy

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Proceedings Article | 4 May 2010 Paper

Optical coatings for deep concave surfaces

Thomas Rahmlow, Jeanne Lazo-Wasem, Mark Moran, Linda Johnson

Proceedings Volume 7660, 766026 (2010) https://doi.org/10.1117/12.850313

KEYWORDS: Coating, Plasma, Glasses, Sputter deposition, Argon, Magnetism, Oxygen, Aluminum nitride, Nose, Aluminum

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Proceedings Article | 7 May 2009 Paper

Filters for dual band infrared imagers

Thomas Rahmlow, Jeanne Lazo-Wasem, Scott Wilkinson, Flemming Tinker

Proceedings Volume 7298, 72982J (2009) https://doi.org/10.1117/12.820059

KEYWORDS: Linear filtering, Optical filters, Reflection, Infrared radiation, Beam splitters, Bandpass filters, Sensors, Visible radiation, Coating, Infrared imaging

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Proceedings Article | 15 April 2008 Paper

Dual-band antireflection coatings for the infrared

Thomas Rahmlow, Jeanne Lazo-Wasem, Scott Wilkinson, Flemming Tinker

Proceedings Volume 6940, 69400T (2008) https://doi.org/10.1117/12.780288

KEYWORDS: Autoregressive models, Antireflective coatings, Reflection, Germanium, Coating, Infrared radiation, Zinc, Refractive index, Infrared coatings, Long wavelength infrared

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Proceedings Article | 18 May 2006 Paper

Narrow band infrared filters with broad field of view

Thomas Rahmlow, Jr., Jeanne Lazo-Wasem, Edward Gratrix

Proceedings Volume 6206, 62062S (2006) https://doi.org/10.1117/12.683972

KEYWORDS: Linear filtering, Optical filters, Reflection, Modulation, Refractive index, Control systems, Absorbance, Optical coatings, Germanium, Optical filtering

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Proceedings Article | 8 October 1998 Paper

Characterization of far-infrared optical thin film materials and blends: AgBr, AgCl, KBr, Csl, and CsBr

Thomas Rahmlow, Jeanne Lazo-Wasem, David Rahmlow

Proceedings Volume 3425, (1998) https://doi.org/10.1117/12.326681

KEYWORDS: Silicon, Reflection, Visible radiation, Refractive index, Thin films, Optical filters, Absorption, Crystals, Optical coatings, Zinc

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Proceedings Article | 1 October 1997 Paper

Rugate and discrete hybrid filter designs

Thomas Rahmlow, Jeanne Lazo-Wasem

Proceedings Volume 3133, (1997) https://doi.org/10.1117/12.290199

KEYWORDS: Optical coatings, Apodization, Absorbance, Optical filters, Linear filtering, Gradient-index optics, Modulation, Superposition, Reflection, Digital filtering

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Proceedings Article | 1 October 1997 Paper

Wavelet algorithms for in-situ monitoring of thin-film deposition

Thomas Rahmlow, Jeanne Lazo-Wasem, David Rahmlow

Proceedings Volume 3133, (1997) https://doi.org/10.1117/12.279105

KEYWORDS: Absorbance, Wavelets, Fourier transforms, Reflection, Optical filters, Optical coatings, Wavelet transforms, Absorption, Thin film deposition, Reflectors

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Proceedings Article | 2 November 1993 Paper

Gradient index film fabrication using optical control techniques

Bruce Tirri, Jeanne Lazo-Wasem, Thomas Rahmlow

Proceedings Volume 2046, (1993) https://doi.org/10.1117/12.163553

KEYWORDS: Control systems, Raman spectroscopy, Reflectivity, Refractive index, Optical filters, Gradient-index optics, Crystals, Fabrication, Control systems design, Signal detection

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Proceedings Article | 2 November 1993 Paper

Graded period rugates

Thomas Rahmlow, Bruce Tirri

Proceedings Volume 2046, (1993) https://doi.org/10.1117/12.163552

KEYWORDS: Reflectors, Reflection, Refractive index, Classification systems, Superposition, Absorption, Mirrors, Coating, Linear filtering, Optical filters

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Showing 5 of 20 publications

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