First light of the 6.5-m MMT adaptive optics system

Astronomical Adaptive Optics Systems and Applications, 2003

The adaptive optics system of the 6.5m MMT with its deformable secondary has seen first light on the sky in November 2002. Since then, it has logged over 30 nights at the telescope and has been used with several scientific cameras and a dedicated IR infrared camera. Results so far are extremely encouraging with Strehls of up to 20% in H-band and 98% in M limited in part by the control algorithm that is being improved. Reliability of the deformable secondary mirror (DM) has been remarkable with only one occurrence of a malfunction that required removing the secondary from its hub. In this paper, we review the milestones achieved and the performances obtained in the first year of operation. We will also address the operational constraints associated with the deformable secondary and the steps taken to relax these constraints. We show that despite its apparent complexity, an adaptive secondary AO system can be operated with modest effort from the telescope and AO staff

SPIE Proceedings, 2003

In this communication, we present the progress of the 6.5m MMT adaptive optics system. During the last part of 2001 and the 1 st part of 2002, the system has been validated in the laboratory statically and dynamically with sample frequencies of up to 550 Hz. In June 2002, an attempt has been made to make this system work on the telescope but has been hampered by mechanical failures. However, ease of installation of the system and open-loop operation of the mirror was demonstrated at this occasion and offers reasons to be optimistic on the future of the system. The MMT-AO system is the first AO system to compensate the aberrated wavefront at the telescope's secondary mirror. This approach has unique advantages in terms of optical simplicity, high throughput and low emissivity. Its realization presents many technical challenges, which have now been overcome. Today, the deformable mirror is characterized and accepted. It features a 1.8 mm thick 640mm diameter convex aspheric mirror (manufactured at the Steward Observatory Mirror Lab), mounted on a 50 mm thick ULE reference body with 336 actuators, as well as a cluster of 168 DSP's and associated analog circuitry for position sensing and actuator driving. The system has been characterized in the laboratory at sampling speeds up to 550 Hz and had been integrated on the telescope.

Adaptive Optical System Technologies II, 2003

In this communication, we present the progress of the 6.5m MMT adaptive optics system. During the last part of 2001 and the 1 st part of 2002, the system has been validated in the laboratory statically and dynamically with sample frequencies of up to 550 Hz. In June 2002, an attempt has been made to make this system work on the telescope but has been hampered by mechanical failures. However, ease of installation of the system and open-loop operation of the mirror was demonstrated at this occasion and offers reasons to be optimistic on the future of the system. The MMT-AO system is the first AO system to compensate the aberrated wavefront at the telescope's secondary mirror. This approach has unique advantages in terms of optical simplicity, high throughput and low emissivity. Its realization presents many technical challenges, which have now been overcome. Today, the deformable mirror is characterized and accepted. It features a 1.8 mm thick 640mm diameter convex aspheric mirror (manufactured at the Steward Observatory Mirror Lab), mounted on a 50 mm thick ULE reference body with 336 actuators, as well as a cluster of 168 DSP's and associated analog circuitry for position sensing and actuator driving. The system has been characterized in the laboratory at sampling speeds up to 550 Hz and had been integrated on the telescope.

Adaptive Optics Systems and Technology II, 2002

The adaptive optics (AO) system for the 6.5 m MMT conversion telescope is the first to compensate the aberrated wavefront at the telescope's secondary mirror. This approach has unique advantages in terms of optical simplicity, high throughput and low emissivity. Its realization presents many technical challenges, which have now been overcome. The deformable mirror is now characterized and accepted. It features a 1.9 mm thick 640mm diameter convex aspheric mirror (manufactured at the Steward Observatory Mirror Lab), mounted on a 50 mm thick ULE reference body with 336 actuators, as well as a cluster of 168 DSP's and associated analog circuitry. A wavefront sensor with integrated CCD and lenslet array has also been completed. The complete system is now starting to produce laboratory results, which we present below. Closed loop operation is tested under an auto-collimation illumination system that reflects aberrated artificial starlight from the convex secondary.

Adaptive Optics Systems and Technology, 1999

We will present a system to perform closed-loop optical tests of the 64 cm diameter, 336 actuator adaptive secondary made at the Steward Observatory Mirror Laboratory. T esting will include Shack-Hartmann wavefront sensing and modal correction of static and dynamic aberrated wavefronts. The test optical system called the`Shimmulator' is designed so that experiments can be made with both the focal plane instrument and secondary installed in their normal con guration at the MMT, or with the same 9 m spacing in a laboratory test tower. The convex secondary will be illuminated at normal incidence through two 70 cm diameter lenses mounted just below. The arti cial, aberrated star is projected from near the wavefront sensor in the Cassegrain focus assembly. Computer generated holograms correct for spherical aberration in the relay optics at the test wavelengths of 0.594 and 1.5 m. Atmospheric turbulence is reproduced by t wo spinning transmission plates imprinted with Kolmogorov turbulence. The Shimmulator will give us the opportunity to test fully the adaptive optics system before installation at the new MMT, hence saving much precious telescope time.

Adaptive Optical System Technologies, 1998

The Multiple Mirror Telescope (MMT) is now being replaced by a single 6.5 m telescope 1 which will have an integral adaptive optics system optimized for near infrared operation. We illustrate key results obtained with low-order adaptive optics at the MMT and report on progress on the major components of the system for the new telescope. We also give a brief update on the status of the telescope itself. First light for the adaptive system is expected in mid 1999.

Proc. sPIE, 2002

The adaptive optics (AO) system for the 6.5 m MMT conversion telescope is the first to compensate the aberrated wavefront at the telescope's secondary mirror. This approach has unique advantages in terms of optical simplicity, high throughput and low emissivity. Its realization presents ...

Proceedings of SPIE, 1999

We will present a system to perform closed-loop optical tests of the 64 cm diameter, 336 actuator adaptive secondary made at the Steward Observatory Mirror Laboratory. T esting will include Shack-Hartmann wavefront sensing and modal correction of static and dynamic aberrated wavefronts. The test optical system called the`Shimmulator' is designed so that experiments can be made with both the focal plane instrument and secondary installed in their normal con guration at the MMT, or with the same 9 m spacing in a laboratory test tower. The convex secondary will be illuminated at normal incidence through two 70 cm diameter lenses mounted just below. The arti cial, aberrated star is projected from near the wavefront sensor in the Cassegrain focus assembly. Computer generated holograms correct for spherical aberration in the relay optics at the test wavelengths of 0.594 and 1.5 m. Atmospheric turbulence is reproduced by t wo spinning transmission plates imprinted with Kolmogorov turbulence. The Shimmulator will give us the opportunity to test fully the adaptive optics system before installation at the new MMT, hence saving much precious telescope time.

Optics Photonics News, 1999

The adaptive optics system for the 6.5 m MMT conversion telescope will be the first to compensate the aberrated wavefront at the telescope's secondary mirror. This approach has unique advantages in terms of optical simplicity, high throughput and low emissivity. We report here the present state of construction, and the results of static and dynamic performance tests of the Cassegrain optical package.

Advancements in Adaptive Optics, 2004

The Natural Guide Star (NGS) Adaptive Optics System at the MMT Telescope (MMTAO) on Mt. Hopkins in Southern Arizona is the first in the world the use the secondary mirror as the correcting deformable mirror. Its 2.0 mm thin shell mirror, whose shape is controlled by 336 voice coil actuators, allows for nearly maximum throughput of light into the science camera. With several more deformable secondary mirrors coming online in the next few years, the lessons learned building, characterizing and operating the MMT Adaptive Optic System has proven to be quite valuable. These lessons will be discussed as well as future plans for the MMTAO System.