Dr. Gerard van Harten Profile

Dr. Gerard van Harten

Scientist

SPIE Involvement:

Author

Publications (16)

Proceedings Article | 16 September 2021 Paper

Paper

Polarimetric calibration of the multi-angle imager for aerosols (MAIA)

Gerard van Harten, Ab Davis, David Diner, Taryn Bailey, Emily Brageot, Carol Bruegge, Bruce Hancock, Leina Hutchinson, Kenneth Manatt, Saagar Patel, John Pearson, Brian Rheingans, Jagmit Sandhu, Jacob Shelton, Amanda Steffy, Daniel Warner, Thomas Werne

Proceedings Volume 11858, 118580I (2021) https://doi.org/10.1117/12.2600345

KEYWORDS: Calibration, Polarizers, Cameras, Polarimetry, Polarization, Modulation, Sensors, Aerosols, Remote sensing

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NASA’s Multi-Angle Imager for Aerosols (MAIA) mission, under development at the Jet Propulsion Laboratory, is designed to study the adverse health effects of different types of particulate air pollution. Planned for launch in late 2022 for a 3-year mission, the MAIA satellite instrument will focus on a selected set of metropolitan target areas, where air quality monitors and health data are available. Aerosol concentration and speciation are inferred from multi-angle measurements of backscattered sunlight in 14 spectral bands from 350-2200 nm, with bands near 442, 645 and 1040 nm measuring the degree (DoLP) and angle of linear polarization (AoLP) in addition to radiance. The pushbroom camera has a ~240-km cross-track field of view with a nadir resolution of ~200 m, and is mounted onto a biaxial gimbal to provide along-track view angles within ±60°, to extend the field of regard to ±48°, and to view the instrument’s onboard calibrator (OBC) and dark target. The OBC consists of a sunlit transmissive diffuser, followed by 12 polarizers at different orientations. MAIA’s polarimetry is implemented using miniature wiregrid polarizers on the focal plane array, and dual photoelastic modulators (PEMs) and achromatic quarter-wave plates to rapidly rotate the polarization. The resulting ~26-Hz intensity modulation encodes the linearly polarized and total radiance in each pixel, leaving the DoLP and AoLP insensitive to gain calibration. We report on the polarimetric calibration of the MAIA camera using a vacuum-compatible polarization state generator, consisting of a 1600W Xenon lamp, 12-inch integrating sphere, and rotating high-extinction polarizer. Mueller-matrix-based calibration coefficients for each detector pixel are derived from measurements at multiple polarizer angles, and are used to correct the measurements for instrumental polarization aberrations. Prior to flight, the calibrated MAIA camera is panned across the OBC to characterize its output, using uniform illumination with an irradiance similar to the Sun.

Proceedings Article | 1 August 2021 Presentation + Paper

Presentation + Paper

Multi-Angle Imager for Aerosols (MAIA) spectral and radiometric calibration

Carol Bruegge, Ab Davis, Tarek Nagaty, Brian Rheingans, Jagmit Sandhu, David Scott, Gerard Van Harten

Proceedings Volume 11829, 118290T (2021) https://doi.org/10.1117/12.2594908

KEYWORDS: Cameras, Sensors, Calibration, Monochromators, Optical spheres, Spectral calibration

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Proceedings Article | 1 August 2021 Presentation + Paper

Presentation + Paper

Geometric calibration of the Multi-Angle Imager for Aerosols (MAIA)

Jagmit Sandhu, Brian Rheingans, Ab Davis, Gerard van Harten, Carol Bruegge

Proceedings Volume 11829, 118290U (2021) https://doi.org/10.1117/12.2595016

KEYWORDS: Cameras, Sensors, Calibration, Polarimetry, Aerosols, Distortion

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Proceedings Article | 20 November 2017 Open Access

Open Access

Paper

SPEX: the Spectropolarimeter for Planetary Exploration

J. H. Rietjens, F. Snik, D. Stam, J. Smit, G. van Harten, C. Keller, A. Verlaan, E. Laan, R. ter Horst, R. Navarro, K. Wielinga, S. Moon, R. Voors

Proceedings Volume 10565, 105651C (2017) https://doi.org/10.1117/12.2309231

KEYWORDS: Polarization, Atmospheric particles, Modulation, Jupiter, Wave plates, Polarimetry, Earth's atmosphere, Space operations, Clouds, Phase shift keying

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Proceedings Article | 20 November 2017 Open Access

Open Access

Paper

Spectropolarimetry for earth observations: a novel method for characterization of aerosols and clouds

Oana Van der Togt, Ad Verlaan, Kees Moddemeijer, Martijn Smit, Jeroen Rietjens, Otto Hasekamp, Daphne Stam, Frans Snik, Gerard van Harten

Proceedings Volume 10564, 105641S (2017) https://doi.org/10.1117/12.2309041

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Proceedings Article | 17 November 2017 Open Access

Open Access

Paper

SPEX: a highly accurate spectropolarimeter for atmospheric aerosol characterization

J. H. Rietjens, J. Smit, A. di Noia, O. Hasekamp, G. van Harten, F. Snik, C. Keller

Proceedings Volume 10563, 1056344 (2017) https://doi.org/10.1117/12.2304227

KEYWORDS: Aerosols, Polarimetry, Polarization, Scattering, Modulation, Atmospheric particles, Prototyping, Glasses, Astronomical imaging, Refractive index

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Global characterization of atmospheric aerosol in terms of the microphysical properties of the particles is essential for understanding the role aerosols in Earth climate [1]. For more accurate predictions of future climate the uncertainties of the net radiative forcing of aerosols in the Earth’s atmosphere must be reduced [2]. Essential parameters that are needed as input in climate models are not only the aerosol optical thickness (AOT), but also particle specific properties such as the aerosol mean size, the single scattering albedo (SSA) and the complex refractive index. The latter can be used to discriminate between absorbing and non-absorbing aerosol types, and between natural and anthropogenic aerosol. Classification of aerosol types is also very important for air-quality and health-related issues [3].

Remote sensing from an orbiting satellite platform is the only way to globally characterize atmospheric aerosol at a relevant timescale of ∼ 1 day [4]. One of the few methods that can be employed for measuring the microphysical properties of aerosols is to observe both radiance and degree of linear polarization of sunlight scattered in the Earth atmosphere under different viewing directions [5][6][7]. The requirement on the absolute accuracy of the degree of linear polarization P_L is very stringent: the absolute error in P_L must be smaller then 0.001+0.005⋅P_L in order to retrieve aerosol parameters with sufficient accuracy to advance climate modelling and to enable discrimination of aerosol types based on their refractive index for air-quality studies [6][7].

In this paper we present the SPEX instrument, which is a multi-angle spectropolarimeter that can comply with the polarimetric accuracy needed for characterizing aerosols in the Earth’s atmosphere. We describe the implementation of spectral polarization modulation in a prototype instrument of SPEX and show results of ground based measurements from which aerosol microphysical properties are retrieved.

SPIE Journal Paper | 27 October 2017 Open Access

Open Access

Polarization modeling and predictions for DKIST part 2: application of the Berreman calculus to spectral polarization fringes of beamsplitters and crystal retarders

David M. Harrington, Frans Snik, Christoph U. Keller, Stacey R. Sueoka, Gerard van Harten

JATIS, Vol. 3, Issue 04, 048001, (October 2017) https://doi.org/10.1117/12.10.1117/1.JATIS.3.4.048001

KEYWORDS: Wave plates, Crystals, Coating, Polarization, Quartz, Antireflective coatings, Interfaces, Calibration, Calculus, Reflection

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Proceedings Article | 30 August 2017 Presentation + Paper

Presentation + Paper

Polarization modeling and predictions for DKIST part 2: application of the Berreman calculus to spectral polarization fringes of beamsplitters and crystal retarders

David Harrington, Frans Snik, Christoph Keller, Stacey Sueoka, Gerard van Harten

Proceedings Volume 10407, 104070A (2017) https://doi.org/10.1117/12.2274046

KEYWORDS: Polarization, Wave plates, Systems modeling, Polarimetry, Calculus, Solar telescopes, Calibration, Optical coatings, Remote sensing, Polarization analysis

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Proceedings Article | 1 September 2015 Paper

Paper

A multi-domain full-Stokes polarization modulator that is efficient for 300-2500nm spectropolarimetry

Frans Snik, Gerard van Harten, Andrey Alenin, Israel Vaughn, J. Tyo

Proceedings Volume 9613, 96130G (2015) https://doi.org/10.1117/12.2187459

KEYWORDS: Modulation, Modulators, Polarization, Polarimetry, Demodulation, Quartz, Wave plates, Prototyping, Spectral resolution, Manufacturing

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Proceedings Article | 1 September 2015 Paper

Paper

Accurate spectrally modulating polarimeters for atmospheric aerosol characterization

Jeroen Rietjens, Martijn Smit, Gerard van Harten, Antonio Di Noia, Otto Hasekamp, Jos de Boer, Hester Volten, Frans Snik, Christoph Keller

Proceedings Volume 9613, 96130S (2015) https://doi.org/10.1117/12.2188024

KEYWORDS: Aerosols, Prototyping, Polarization, Modulation, Polarimetry, Atmospheric particles, Observatories, Spectrographs, Refractive index, Earth's atmosphere

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Proceedings Article | 24 July 2014 Paper

Paper

UVMag: Space UV and visible spectropolarimetry

Martin Pertenais, Coralie Neiner, Laurent Parès, Pascal Petit, Frans Snik, Gerard van Harten

Proceedings Volume 9144, 91443B (2014) https://doi.org/10.1117/12.2060561

KEYWORDS: Polarimetry, Polarization, Stars, Ultraviolet radiation, Birefringence, Modulation, Visible radiation, Magnesium fluoride, Modulators, Sensors

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Proceedings Article | 12 June 2014 Paper

Paper

Five-dimensional optical instrumentation: combining polarimetry with time-resolved integral-field spectroscopy

M. Rodenhuis, F. Snik, G. van Harten, J. Hoeijmakers, C. Keller

Proceedings Volume 9099, 90990L (2014) https://doi.org/10.1117/12.2053241

KEYWORDS: Polarization, Modulation, Polarimetry, Sensors, Wave plates, Spectroscopes, Modulators, Exoplanets, Optical instrument design, Microlens array

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Proceedings Article | 5 October 2012 Paper

Paper

Design of a full-Stokes polarimeter for VLT/X-shooter

Frans Snik, Gerard van Harten, Ramon Navarro, Paul Groot, Lex Kaper, Alfred de Wijn

Proceedings Volume 8446, 844625 (2012) https://doi.org/10.1117/12.926163

KEYWORDS: Polarization, Polarimetry, Modulators, Stars, Magnetism, Modulation, Demodulation, Spectrographs, Quartz, Crystals

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Proceedings Article | 3 October 2011 Paper

Paper

Spectropolarimeter for planetary exploration (SPEX): performance measurements with a prototype

Robert Voors, Scott Moon, Sandro Hannemann, Jeroen H. Rietjens, Gerard van Harten, Frans Snik, Martijn Smit, Daphne Stam, Christoph Keller, Erik Laan, Adrianus Verlaan, Willem Vliegenthart, Rik ter Horst, Ramón Navarro, Klaas Wielenga

Proceedings Volume 8176, 81760D (2011) https://doi.org/10.1117/12.897706

KEYWORDS: Polarization, Prototyping, Modulation, Glasses, Sensors, Atmospheric particles, Earth's atmosphere, Electronics, Wave plates, Crystals

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Proceedings Article | 10 September 2011 Paper

Paper

Prototyping for the Spectropolarimeter for Planetary EXploration (SPEX): calibration and sky measurements

Gerard van Harten, Frans Snik, Jeroen H. Rietjens, J. Martijn Smit, Jozua de Boer, Renia Diamantopoulou, Otto Hasekamp, Daphne Stam, Christoph Keller, Erik Laan, Ad Verlaan, Willem Vliegenthart, Rik ter Horst, Ramón Navarro, Klaas Wielinga, Sandro Hannemann, Scott Moon, Robert Voors

Proceedings Volume 8160, 81600Z (2011) https://doi.org/10.1117/12.893741

KEYWORDS: Polarization, Aerosols, Prototyping, Modulation, Atmospheric particles, Polarimetry, Calibration, Wave plates, Scattering, Climatology

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We present the Spectropolarimeter for Planetary EXploration (SPEX), a high-accuracy linear spectropolarimeter measuring from 400 to 800 nm (with 2 nm intensity resolution), that is compact (~ 1 liter), robust and lightweight. This is achieved by employing the unconventional spectral polarization modulation technique, optimized for linear polarimetry. The polarization modulator consists of an achromatic quarter-wave retarder and a multiple-order retarder, followed by a polarizing beamsplitter, such that the incoming polarization state is encoded as a sinusoidal modulation in the intensity spectrum, where the amplitude scales with the degree of linear polarization, and the phase is determined by the angle of linear polarization. An optimized combination of birefringent crystals creates an athermal multiple-order retarder, with a uniform retardance across the field of view. Based on these specifications, SPEX is an ideal, passive remote sensing instrument for characterizing planetary atmospheres from an orbiting, air-borne or ground-based platform. By measuring the intensity and polarization spectra of sunlight that is scattered in the planetary atmosphere as a function of the single scattering angle, aerosol microphysical properties (size, shape, composition), vertical distribution and optical thickness can be derived. Such information is essential to fully understand the climate of a planet. A functional SPEX prototype has been developed and calibrated, showing excellent agreement with end-to-end performance simulations. Calibration tests show that the precision of the polarization measurements is at least 2 • 10^-4. We performed multi-angle spectropolarimetric measurements of the Earth's atmosphere from the ground in conjunction with one of AERONET's sun photometers. Several applications exist for SPEX throughout the solar system, a.o. in orbit around Mars, Jupiter and the Earth, and SPEX can also be part of a ground-based aerosol monitoring network.

Proceedings Article | 6 August 2010 Paper

Paper

SPEX: the spectropolarimeter for planetary exploration

Frans Snik, Jeroen H. H. Rietjens, Gerard van Harten, Daphne Stam, Christoph Keller, J. Martijn Smit, Erik Laan, Ad Verlaan, Rik ter Horst, Ramón Navarro, Klaas Wielinga, Scott Moon, Robert Voors

Proceedings Volume 7731, 77311B (2010) https://doi.org/10.1117/12.857941

KEYWORDS: Polarization, Atmospheric particles, Polarimetry, Aerosols, Modulation, Clouds, Atmospheric modeling, Planets, Mars, Scattering

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Showing 5 of 16 publications

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