Dr. Alireza Azizi Profile

Dr. Alireza Azizi

Project Element Manager at Jet Propulsion Lab

SPIE Involvement:

Author

Publications (13)

Proceedings Article | 16 September 2019 Presentation + Paper

Technology maturity update for the Habitable-zone Exoplanet Imaging Observatory (HabEx) concept

Rhonda Morgan, Keith Warfield, H. Phil Stahl, Bertrand Mennesson, Gary Kuan, Bala Balasubramanian, Dimitri Mawet, Shouleh Nikzad, John Hennessy, Ali Azizi, Stuart Shaklan, Eugene Serabyn

Proceedings Volume 11115, 111150N (2019) https://doi.org/10.1117/12.2529766

KEYWORDS: Exoplanets, Observatories, Telescopes, Coronagraphy, Mirrors, Optical instrument design, Deformable mirrors, Wavefronts, Segmented mirrors, Sensors

Read Abstract +

Proceedings Article | 13 April 2018 Paper

Progress towards picometer accuracy laser metrology for the space interferometry mission: update

Peter Halverson, Oscar Alvarez-Salazar, Alireza Azizi, Frank Dekens, Bijan Nemati, Feng Zhao

Proceedings Volume 10568, 105682L (2018) https://doi.org/10.1117/12.2500128

Read Abstract +

Proceedings Article | 5 September 2017 Presentation + Paper

Laser metrology for ultra-stable space-based coronagraphs

Joel Nissen, Alireza Azizi, Feng Zhao, Shannon Kian Zareh, Shanti Rao, Jeffrey Jewell, Dustin Moore

Proceedings Volume 10398, 103980I (2017) https://doi.org/10.1117/12.2274704

KEYWORDS: Space telescopes, Laser metrology, Active optics, Wavefronts, Telescopes, Optical alignment, Optical sensing, Wavefront sensors

Read Abstract +

Proceedings Article | 16 September 2015 Paper

Control design for momentum-compensated fast steering mirror for WFIRST-AFTA coronagraph instrument

Keith Patterson, Joel Shields, Xu Wang, Hong Tang, Ali Azizi, Paul Brugarolas, Milan Mandic, Fang Shi

Proceedings Volume 9605, 96052C (2015) https://doi.org/10.1117/12.2191813

KEYWORDS: Coronagraphy, Sensors, Mirrors, Telescopes, Space telescopes, Device simulation, Wavefronts, Stars, Control systems, Ferroelectric materials

Read Abstract +

Proceedings Article | 2 September 2008 Paper

Broadband white light laser combiner system

Daniel Ryan, Alireza Azizi, Xin An, Hong Tang, Richard Demers

Proceedings Volume 7056, 705623 (2008) https://doi.org/10.1117/12.804262

KEYWORDS: Light, Cameras, Multimode fibers, Calibration, Light sources, Mirrors, Fiber lasers, Photonic crystal fibers, Single mode fibers, Visible radiation

Read Abstract +

Proceedings Article | 28 July 2008 Paper

Spectral calibration at the picometer level on SCDU (spectral calibration development unit)

Richard Demers, Xin An, Alireza Azizi, Gary Brack, Oliver Lay, Daniel Ryan, Janice Shen, George Sun, Hong Tang, Chengxing Zhai

Proceedings Volume 7013, 70132H (2008) https://doi.org/10.1117/12.790653

KEYWORDS: Spectral calibration, Metrology, Calibration, Wavefronts, Stars, Beam splitters, Servomechanisms, Mirrors, Optical filters, Interferometers

Read Abstract +

Proceedings Article | 14 August 2006 Paper

Measurement of the non-common vertex error of a double corner cube

Alireza Azizi, Martin Marcin, Douglas Moore, Steve Moser, John Negron, Eung-Gi Paek, Daniel Ryan, Alex Abramovici, Paul Best, Ian Crossfield, Bijan Nemati, Tim Neville, B. Platt, Leonard Wayne

Proceedings Volume 6292, 629203 (2006) https://doi.org/10.1117/12.696088

KEYWORDS: Metrology, Prisms, Motion measurement, Interferometers, Interferometry, Beam splitters, Autocollimators, Data modeling, Heterodyning, Laser metrology

Read Abstract +

Proceedings Article | 20 October 2004 Paper

Metrology system for Space Interferometry Mission's system testbed 3

Oscar Alvarez-Salazar, Alireza Azizi, Yekta Gursel, George Sun, Jens Fischer, Arshak Avanesyan, John Shaw

Proceedings Volume 5491, (2004) https://doi.org/10.1117/12.549694

KEYWORDS: Metrology, Error analysis, Interferometers, Motion measurement, Interferometry, Stars, Motion estimation, Monte Carlo methods, Algorithm development, Polarizers

Read Abstract +

Proceedings Article | 20 October 2004 Paper

Kite: status of the external metrology testbed for SIM

Frank Dekens, Oscar Alvarez-Salazar, Alireza Azizi, Steven Moser, Bijan Nemati, John Negron, Timothy Neville, Daniel Ryan

Proceedings Volume 5491, (2004) https://doi.org/10.1117/12.549797

KEYWORDS: Metrology, Stars, Data modeling, Interferometers, Heterodyning, Space operations, Motion measurement, Switches, Bragg cells, Sensors

Read Abstract +

Proceedings Article | 20 October 2004 Paper

SIM system testbed: 3-baseline stellar interferometer on a 9-meter-long flexible structure

Oscar Alvarez-Salazar, Renaud Goullioud, Alireza Azizi

Proceedings Volume 5491, (2004) https://doi.org/10.1117/12.549690

KEYWORDS: Interferometers, Stars, Metrology, Mirrors, Error analysis, Interferometry, Device simulation, Space operations, Motion measurement, Reflectors

Read Abstract +

Proceedings Article | 19 November 2003 Paper

Experimental results from the optical planet detector interferometer

J. Kent Wallace, Mike Shao, Benjamin Lane, Bruce Levine, F. Loya, Alireza Azizi, Buck Holmes, F. Aguayo, J. Negron, G. Sanchez, Robert Gappinger

Proceedings Volume 5170, (2003) https://doi.org/10.1117/12.506356

KEYWORDS: Interferometers, Metrology, Glasses, Laser metrology, Polarization, Nulling interferometry, Beam splitters, Sensors, Optical fibers, Planets

Read Abstract +

Proceedings Article | 26 February 2003 Paper

Mitigation of atmospheric effects in SIM's astrometric interferometer testbed 3

Oscar Alvarez-Salazar, Renaud Goullioud, Bijan Nemati, Alireza Azizi

Proceedings Volume 4852, (2003) https://doi.org/10.1117/12.460724

KEYWORDS: Interferometers, Stars, Metrology, Atmospheric sciences, Atmospheric optics, Signal to noise ratio, Atmospheric propagation, Filtering (signal processing), Optical tracking, Electronic filtering

Read Abstract +

The Space Interferometry Mission's (SIM) shared-baseline astrometric interferometer System Test Bed 3 (STB3) has been constructed at JPL. STB3's objective is to use two of its interferometers (guides) for low frequency (0 to 1 Hz) fringe stabilization in the third one (science). This approach - being proposed for the first time in the context of space based observatories - is needed given the dim nature of science stars to be observed by SIM. Fringe stability is mostly affected by the low frequency attitude motion of the test bed's instrument table, with the inevitable exception of instrument vibration, thermal drift, and atmospheric fluctuations. Relative changes in table attitude cause optical path changes in the guide interferometers, which are tracked, linearly combined and fed forward to the science interferometer's active delay line to stabilize its optical path. This technique for tracking fringes in the science interferometer is possible because the position of the guide stars relative to the science star is well known. This open loop fringe tracking technique is dubbed Path-length Feed Forward, or PFF. In STB3, current fringe stability in the science interferometer using the PFF technique is at 50 to 60 nanometers RMS (from 0 to 500 Hz). Compare this to 15 to 20 nm RMS fringe stability in the guide interferometers, which operate in closed loop mode. Vibration, thermal drift and atmospherics in the science and guide interferometers are largely eliminated with the use of an internal metrology system. By design, mechanical vibrations are above the bandwidth of the interferometer system, and are passively rejected. Nevertheless, the internal metrology system can easily reject current low-level vibrations in STB3 down to the 6-nanometer RMS level. Fringe tracking error in the science interferometer due to atmospherics is currently about 40 nanometers RMS at frequencies below 1.0 Hz. In SIM, the error in this low frequency band must be no more than 6 nm RMS. This error arises because the optical path stabilized by the internal metrology system is not equal to taht of the starlight, so not all atmospheric fluctuations in the starlight path can be stabilized. Therefore, there is a need to reduce the strength of atmospheric fluctuations or to filter them from the PFF command. In STB3 the strength of atmospheric fluctuations is already reduced with the use of optical path enclosures, which brought these fluctuations down from ~170nm RMS to their current levels of ~66nm RMS with a spread of 20nm. Simulations show that signal to noise ratios are generally not sufficient to filter atmospheric errors on-line.

Proceedings Article | 5 July 2000 Paper

Optical design of the SIM system testbed III

Renaud Goullioud, Alireza Azizi

Proceedings Volume 4006, (2000) https://doi.org/10.1117/12.390280

KEYWORDS: Metrology, Stars, Interferometers, Beam splitters, Mirrors, Polarization, Ferroelectric materials, Wavefronts, Sensors, Diffraction gratings

Read Abstract +

Showing 5 of 13 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years