Research

iLocater

My research focuses on the design, development and construction of iLocater, a new ultra-precise radial velocity instrument to search for planets around other stars. Designed for use with the extreme adaptive optics (AO) system of the the dual 8.4m mirror Large Binocular Telescope (LBT) in Arizona, the instrument comprises three main components:

  1. An acquisition camera to couple light from each telescope dish into separate single-mode optical fibers.
  2. A fiber-fed high-resolution spectrograph working at Y- and J-band wavelengths housed inside an temperature stable cryostat.
  3. A calibration system to provide an absolute wavelength reference on the spectrograph detector and act as a diagnostic tool for systematic effects.

My work focuses on both the acquisition camera and cryostat design of the instrument. I am taking the lead on cryostat design and thermal control system and am an integral part of the acquisition camera design team.

To find out more about iLocater, visit the iLocater website.

Acquisition Camera

The iLocater acquisition camera independently couples AO corrected light from the two sides of the LBT into single-mode fibers. The camera is mounted on the existing Large Binocular Telescope Interferometer (LBTI) at the LBT. Achieving an efficient coupling into single-mode fibers is challenging and has never before been repeatedly achieved on-sky.

We installed a demonstration system on the LBT in spring 2016 use the right telescope dish. This instrument was the first instrument to test single-mode fiber coupling on-sky at near-infrared wavelengths using a high-order adaptive optics system and a successful demonstration of this capability was a critical step in the development of iLocater. During the run, a sustained 20% coupling was achieved and work is on-going to fully understand the data collected and allow further improvements for the fiber-coupling system which will be installed as part of the iLocater instrument.

CAD rendering of LBTI showing the demonstration system mounted on the right (DX) side of LBTI. CAD rendering of the demonstration system which was installed at the LBT in April 2016.
The iLocater team operating the telescope AO system and demonstration fiber-coupling system (from front to back - J.Crass, R. Ketterer, A. Bechter, E. Bechter). Installing the iLocater fiber-coupling demonstration on the right hand (DX) side of the LBT.

You can find out more about the iLocater acquisition camera on the posters we presented at the 225th Meeting of the AAS in Seattle, January 2015 and SPIE in San Diego, August 2015 and the accompanying conference proceedings.

AAS 225 iLocater Poster

SPIE - August 2015 Poster

SPIE - August 2015 Conference Proceedings - Design of the iLocater acquisition camera demonstration system

Cryostat

The cryostat which houses the spectrograph for iLocater is critical to ensuring a temperature and pressure stable environment for the optics. This is needed to ensure changes in the spectrum of a star measured by the instrument are real and not from an instrument change.

Currently the cryostat is in its conceptual stage with work on the optical design of the spectrograph converging to a final design. Upon its completion, a finalized cryostat design will be developed with thermal and mechanical modelling being undertaken to ensure the required stability can be achieved.

CAD rendering of the conceptual design of the iLocater cryostat. The optics are mounted to an Invar board to minimize displacements with temperature fluctuation. This is housed within two radiation shields, minimizing thermal fluctuations and achieving a stability of better than 1mK.

High-sensitivity wavefront sensing for Adaptive Optics

The focus of my Ph.D. research at the Institute of Astronomy, University of Cambridge was with the Adaptive Optics Lucky Imager (AOLI) instrument. This instrument, initially being designed for use at the William Herschel Telescope, is being built by a collaboration of research institutions in Europe and aims to provide diffraction limited imaging at visible wavelengths using large ground-based telescopes.

You can download a copy of my PhD thesis.