MPS contributions to PHI

The MPS is assigned with the system responsibility for the implementation of the PHI instrument. This comprises the development of a stable housing and its connections to the spacecraft's main body. In addition, the MPS is responsible for the full opto-mechanical development of the High Resolution Telescope and a feed select mechanism for choosing between the two telescopes will be developed under authority of the MPS. The institute will also provide the focal plane assembly of the PHI instrument. This comprises the development of a fast 2k x 2k APS-detector system and the associated front-end electronics. After successful assembly, test, and calibration the instrument was delivered to Airbus DS, Stevenage, for integration into the spacecraft in April 2017.


Dr. Joachim Woch
Phone:+49 551 384 979 - 447

PHI Team at MPS

Sami K. Solanki (PI)
Joachim Woch (PM)
Werner Curdt
Alex Feller
Achim Gandorfer
Laurent Gizon
Johann Hirzberger
Andreas Lagg
Tino Riethmüller
Jesper Schou
Udo Schuehle

Engineers and Technicians:
Kinga Albert
Miguel Alvarez Copano
Patrick Bambach
Uwe Beckmann
Melani Bergmann
Jörg Bischoff
Jan Bochmann
Bernd Chares
Werner Deutsch
Rainer Enge
German Fernandez Rico
Sophie Frahm
Dietmar Germerott
Bianca Grauf
Lucas Guerrero Vidal
Klaus Heerlein
Jan Heinrichs
Dennis Hirche
Martin Kolleck
Tanja Macke
Thimo Meierdierks
Stefan Meining
Reinhard Meller
Sabrina Meyer
Markus Monecke
Maria Mühlhaus
Marc Ferenc Müller
Reinhard Müller
Dietmar Oberdorfer
Ioanna Papagiannaki
Sandeep Ramanath
Li Song
Michael Sperling
Jan Staub
Stephan Werner
Andreas Zerr


Polarimetric and Helioseismic Imager (PHI)

PHI is a diffraction limited, wavelength tunable, quasi-monochromatic, polarisation sensitive imager. The instrument will provide maps of the magnetic vector and of the line-of-sight (LOS) velocity in the solar photosphere. It will thus probe the deepest layers of the Sun (including the solar interior using helioseismology) of all the instruments on Solar Orbiter. Since the magnetic field anchored at the solar surface produces most of the structures and energetic events in the upper solar atmosphere and significantly influences the heliosphere, PHI plays a key role in reaching the science goals of Solar Orbiter. Extrapolations of the magnetic field observed by PHI into the Sun’s upper atmosphere and heliosphere will provide the information needed for other optical and in-situ instruments onboard Solar Orbiter and also onboard the Parker Solar Probe to analyse and understand the data recorded by them in a proper physical context.

<strong>PHI optics unit</strong>
PHI optics unit

PHI is composed of two telescopes. The off-axis Ritchey-Chrétien High Resolution Telescope (HRT) with an aperture diameter of 160 mm and an effective focal length of approximately 2500 mm will image a fraction of the solar disk at a resolution reaching 150 km at perihelion (the same resolution as the Extreme Ultraviolet Imager’s high resolution channels will have). The refractor Full Disk Telescope (FDT) will be able to image the full solar disk at all phases of the orbit. Each telescope has its own Polarization Modulation Package (PMP) located early in the optical path in order to minimize polarisation cross-talk effects. Polarimetry at a signal to noise level of 103 is baselined for PHI. The HRT and the FDT will sequentially send light to a Fabry-Perot filtergraph system (~ 100 mÅ spectral resolution) and on to a 2048 × 2048 pixel CMOS sensor. PHI has its own Image Stabilization System (ISS) that will compensate spacecraft jitter or other disturbances. This system is composed of a correlation tracker (CT) and a tip-tilt mirror.

Due to the close solar proximity during Solar Orbiter's perihelion passages all instrument components are subject to stringent conditions regarding radiation hardness and thermal stability.

<p>The PHI instrument, ready for end-to-end tests at MPS facilities.</p> Zoom Image

The PHI instrument, ready for end-to-end tests at MPS facilities.

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