1st AO4ELT conference - Adaptive Optics for Extremely Large Telescopes, 2010
We report on the design of an artificial light source for ARGOS, the multiple Rayleigh laser guid... more We report on the design of an artificial light source for ARGOS, the multiple Rayleigh laser guide star (LGS) facility at the Large Binocular Telescope (LBT). Our light source mimics the expected night-time illumination of the adaptive secondary mirror (ASM) by the laser beacons very accurately and provides a way to check the achieved performance, allowing thorough testing of the system during day time. The optical design makes use of computer generated holograms (CGH) and strong aspheres to achieve a very small residual wavefront error. Additional structures on the CGH facilitate quick and precise alignment of the optics in the prime focus. We demonstrate that the scheme can be applied to the current European Extremely Large Telescope (E-ELT) design in a similar way.
International Optical Design Conference 2010, 2010
ABSTRACT We describe the optical design of a calibration unit for the off-axis laser guide stars ... more ABSTRACT We describe the optical design of a calibration unit for the off-axis laser guide stars at the Large Binocular Telescope's ARGOS facility. Artificial stars with the desired wavefront are created using a computer generated hologram.
ARGOS is the Laser Guide Star and Wavefront sensing facility for the Large Binocular Telescope. W... more ARGOS is the Laser Guide Star and Wavefront sensing facility for the Large Binocular Telescope. With first laser light on sky in 2013, the system is currently undergoing commissioning at the telescope. We present the overall status and design, as well as first results on sky. Aiming for a wide field ground layer correction, ARGOS is designed as a multiRayleigh beacon adaptive optics system. A total of six powerful pulsed lasers are creating the laser guide stars in constellations above each of the LBTs primary mirrors. With a range gated detection in the wavefront sensors, and the adaptive correction by the deformable secondary’s, we expect ARGOS to enhance the image quality over a large range of seeing conditions. With the two wide field imaging and spectroscopic instruments LUCI1 and LUCI2 as receivers, a wide range of scientific programs will benefit from ARGOS. With an increased resolution, higher encircled energy, both imaging and MOS spectroscopy will be boosted in signal to noise by a large amount. Apart from the wide field correction ARGOS delivers in its ground layer mode, we already foresee the implementation of a hybrid Sodium with Rayleigh beacon combination for a diffraction limited AO performance.
ABSTRACT ARGOS the Advanced Rayleigh guided Ground layer adaptive Optics System for the LBT (Larg... more ABSTRACT ARGOS the Advanced Rayleigh guided Ground layer adaptive Optics System for the LBT (Large Binocular Telescope) is built by a German-Italian-American consortium. It will be a seeing reducer correcting the turbulence in the lower atmosphere over a field of 2' radius. In such way we expect to improve the spatial resolution over the seeing of about a factor of two and more and to increase the throughput for spectroscopy accordingly. In its initial implementation, ARGOS will feed the two near-infrared spectrograph and imager - LUCI I and LUCI II. The system consist of six Rayleigh lasers - three per eye of the LBT. The lasers are launched from the back of the adaptive secondary mirror of the LBT. ARGOS has one wavefront sensor unit per primary mirror of the LBT, each of the units with three Shack-Hartmann sensors, which are imaged on one detector. In 2010 and 2011, we already mounted parts of the instrument at the telescope to provide an environment for the main sub-systems. The commissioning of the instrument will start in 2012 in a staged approach. We will give an overview of ARGOS and its goals and report about the status and new challenges we encountered during the building phase. Finally we will give an outlook of the upcoming work, how we will operate it and further possibilities the system enables by design.
Effective calibration procedures play an important role for the efficiency and performance of ast... more Effective calibration procedures play an important role for the efficiency and performance of astronomical instrumentation. We report on the calibration scheme for ARGOS, the Laser Guide Star (LGS) facility at the LBT. An artificial light source is used to feign the real laser beacons and perform extensive testing of the system, independent of the time of day and weather conditions, thereby greatly enhancing the time available for engineering. Fibre optics and computer generated holograms (CGHs) are used to generate the necessary wavefront. We present the optomechanical design, and discuss the expected accuracy, as well as tolerances in assembly and alignment.
To achieve high-resolution imaging the standard control algorithm used for classical adaptive opt... more To achieve high-resolution imaging the standard control algorithm used for classical adaptive optics (AO) is the simple but efficient proportional-integral (PI) controller. The goal is to minimize the rms error of the residual wave front. However, using the PI controller, it is not possible to do this. One possible way to minimize the rms error is to use linear quadratic Gaussian (LQG) control. In practice, however, this control algorithm still encounters an unexpected problem that leads to the divergence of control in AO. This paper proposes a modified LQG (MLQG) to solve this issue. The controller is analyzed explicitly. Laboratory tests shows strong stability and high precision compared to the classical control.
Software and Cyberinfrastructure for Astronomy III, 2014
Commissioning time for an instrument at an observatory is precious, especially the night time. Wh... more Commissioning time for an instrument at an observatory is precious, especially the night time. Whenever astronomers come up with a software feature request or point out a software defect, the software engineers have the task to find a solution and implement it as fast as possible. In this project phase, the software engineers work under time pressure and stress to deliver a functional instrument control software (ICS). The shortness of development time during commissioning is a constraint for software engineering teams and applies to the ARGOS project as well. The goal of the ARGOS (Advanced Rayleigh guided Ground layer adaptive Optics System) project is the upgrade of the Large Binocular Telescope (LBT) with an adaptive optics (AO) system consisting of six Rayleigh laser guide stars and wavefront sensors. For developing the ICS, we used the technique Test- Driven Development (TDD) whose main rule demands that the programmer writes test code before production code. Thereby, TDD can yield a software system, that grows without defects and eases maintenance. Having applied TDD in a calm and relaxed environment like office and laboratory, the ARGOS team has profited from the benefits of TDD. Before the commissioning, we were worried that the time pressure in that tough project phase would force us to drop TDD because we would spend more time writing test code than it would be worth. Despite this concern at the beginning, we could keep TDD most of the time also in this project phase This report describes the practical application and performance of TDD including its benefits, limitations and problems during the ARGOS commissioning. Furthermore, it covers our experience with pair programming and continuous integration at the telescope.
1st AO4ELT conference - Adaptive Optics for Extremely Large Telescopes, 2010
We report on the design of an artificial light source for ARGOS, the multiple Rayleigh laser guid... more We report on the design of an artificial light source for ARGOS, the multiple Rayleigh laser guide star (LGS) facility at the Large Binocular Telescope (LBT). Our light source mimics the expected night-time illumination of the adaptive secondary mirror (ASM) by the laser beacons very accurately and provides a way to check the achieved performance, allowing thorough testing of the system during day time. The optical design makes use of computer generated holograms (CGH) and strong aspheres to achieve a very small residual wavefront error. Additional structures on the CGH facilitate quick and precise alignment of the optics in the prime focus. We demonstrate that the scheme can be applied to the current European Extremely Large Telescope (E-ELT) design in a similar way.
International Optical Design Conference 2010, 2010
ABSTRACT We describe the optical design of a calibration unit for the off-axis laser guide stars ... more ABSTRACT We describe the optical design of a calibration unit for the off-axis laser guide stars at the Large Binocular Telescope's ARGOS facility. Artificial stars with the desired wavefront are created using a computer generated hologram.
ARGOS is the Laser Guide Star and Wavefront sensing facility for the Large Binocular Telescope. W... more ARGOS is the Laser Guide Star and Wavefront sensing facility for the Large Binocular Telescope. With first laser light on sky in 2013, the system is currently undergoing commissioning at the telescope. We present the overall status and design, as well as first results on sky. Aiming for a wide field ground layer correction, ARGOS is designed as a multiRayleigh beacon adaptive optics system. A total of six powerful pulsed lasers are creating the laser guide stars in constellations above each of the LBTs primary mirrors. With a range gated detection in the wavefront sensors, and the adaptive correction by the deformable secondary’s, we expect ARGOS to enhance the image quality over a large range of seeing conditions. With the two wide field imaging and spectroscopic instruments LUCI1 and LUCI2 as receivers, a wide range of scientific programs will benefit from ARGOS. With an increased resolution, higher encircled energy, both imaging and MOS spectroscopy will be boosted in signal to noise by a large amount. Apart from the wide field correction ARGOS delivers in its ground layer mode, we already foresee the implementation of a hybrid Sodium with Rayleigh beacon combination for a diffraction limited AO performance.
ABSTRACT ARGOS the Advanced Rayleigh guided Ground layer adaptive Optics System for the LBT (Larg... more ABSTRACT ARGOS the Advanced Rayleigh guided Ground layer adaptive Optics System for the LBT (Large Binocular Telescope) is built by a German-Italian-American consortium. It will be a seeing reducer correcting the turbulence in the lower atmosphere over a field of 2' radius. In such way we expect to improve the spatial resolution over the seeing of about a factor of two and more and to increase the throughput for spectroscopy accordingly. In its initial implementation, ARGOS will feed the two near-infrared spectrograph and imager - LUCI I and LUCI II. The system consist of six Rayleigh lasers - three per eye of the LBT. The lasers are launched from the back of the adaptive secondary mirror of the LBT. ARGOS has one wavefront sensor unit per primary mirror of the LBT, each of the units with three Shack-Hartmann sensors, which are imaged on one detector. In 2010 and 2011, we already mounted parts of the instrument at the telescope to provide an environment for the main sub-systems. The commissioning of the instrument will start in 2012 in a staged approach. We will give an overview of ARGOS and its goals and report about the status and new challenges we encountered during the building phase. Finally we will give an outlook of the upcoming work, how we will operate it and further possibilities the system enables by design.
Effective calibration procedures play an important role for the efficiency and performance of ast... more Effective calibration procedures play an important role for the efficiency and performance of astronomical instrumentation. We report on the calibration scheme for ARGOS, the Laser Guide Star (LGS) facility at the LBT. An artificial light source is used to feign the real laser beacons and perform extensive testing of the system, independent of the time of day and weather conditions, thereby greatly enhancing the time available for engineering. Fibre optics and computer generated holograms (CGHs) are used to generate the necessary wavefront. We present the optomechanical design, and discuss the expected accuracy, as well as tolerances in assembly and alignment.
To achieve high-resolution imaging the standard control algorithm used for classical adaptive opt... more To achieve high-resolution imaging the standard control algorithm used for classical adaptive optics (AO) is the simple but efficient proportional-integral (PI) controller. The goal is to minimize the rms error of the residual wave front. However, using the PI controller, it is not possible to do this. One possible way to minimize the rms error is to use linear quadratic Gaussian (LQG) control. In practice, however, this control algorithm still encounters an unexpected problem that leads to the divergence of control in AO. This paper proposes a modified LQG (MLQG) to solve this issue. The controller is analyzed explicitly. Laboratory tests shows strong stability and high precision compared to the classical control.
Software and Cyberinfrastructure for Astronomy III, 2014
Commissioning time for an instrument at an observatory is precious, especially the night time. Wh... more Commissioning time for an instrument at an observatory is precious, especially the night time. Whenever astronomers come up with a software feature request or point out a software defect, the software engineers have the task to find a solution and implement it as fast as possible. In this project phase, the software engineers work under time pressure and stress to deliver a functional instrument control software (ICS). The shortness of development time during commissioning is a constraint for software engineering teams and applies to the ARGOS project as well. The goal of the ARGOS (Advanced Rayleigh guided Ground layer adaptive Optics System) project is the upgrade of the Large Binocular Telescope (LBT) with an adaptive optics (AO) system consisting of six Rayleigh laser guide stars and wavefront sensors. For developing the ICS, we used the technique Test- Driven Development (TDD) whose main rule demands that the programmer writes test code before production code. Thereby, TDD can yield a software system, that grows without defects and eases maintenance. Having applied TDD in a calm and relaxed environment like office and laboratory, the ARGOS team has profited from the benefits of TDD. Before the commissioning, we were worried that the time pressure in that tough project phase would force us to drop TDD because we would spend more time writing test code than it would be worth. Despite this concern at the beginning, we could keep TDD most of the time also in this project phase This report describes the practical application and performance of TDD including its benefits, limitations and problems during the ARGOS commissioning. Furthermore, it covers our experience with pair programming and continuous integration at the telescope.
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Papers by Diethard Peter
on sky in 2013, the system is currently undergoing commissioning at the telescope. We present the overall status and
design, as well as first results on sky. Aiming for a wide field ground layer correction, ARGOS is designed as a multiRayleigh beacon adaptive optics system. A total of six powerful pulsed lasers are creating the laser guide stars in
constellations above each of the LBTs primary mirrors. With a range gated detection in the wavefront sensors, and the
adaptive correction by the deformable secondary’s, we expect ARGOS to enhance the image quality over a large range
of seeing conditions. With the two wide field imaging and spectroscopic instruments LUCI1 and LUCI2 as receivers, a wide range of scientific programs will benefit from ARGOS. With an increased resolution, higher encircled energy, both
imaging and MOS spectroscopy will be boosted in signal to noise by a large amount. Apart from the wide field
correction ARGOS delivers in its ground layer mode, we already foresee the implementation of a hybrid Sodium with
Rayleigh beacon combination for a diffraction limited AO performance.
on sky in 2013, the system is currently undergoing commissioning at the telescope. We present the overall status and
design, as well as first results on sky. Aiming for a wide field ground layer correction, ARGOS is designed as a multiRayleigh beacon adaptive optics system. A total of six powerful pulsed lasers are creating the laser guide stars in
constellations above each of the LBTs primary mirrors. With a range gated detection in the wavefront sensors, and the
adaptive correction by the deformable secondary’s, we expect ARGOS to enhance the image quality over a large range
of seeing conditions. With the two wide field imaging and spectroscopic instruments LUCI1 and LUCI2 as receivers, a wide range of scientific programs will benefit from ARGOS. With an increased resolution, higher encircled energy, both
imaging and MOS spectroscopy will be boosted in signal to noise by a large amount. Apart from the wide field
correction ARGOS delivers in its ground layer mode, we already foresee the implementation of a hybrid Sodium with
Rayleigh beacon combination for a diffraction limited AO performance.