TICTAC: Turnkey, Inexpensive and Compact Ti:sapphire Astrocomb Concept
Lead Research Organisation:
Heriot-Watt University
Department Name: Sch of Engineering and Physical Science
Abstract
In 1929, Edwin Hubble reported that spectra from further away galaxies were more redshifted, providing foundational evidence for the expansion of the universe.
Almost 100 years later, some of the most exciting science cases for optical astronomy rely on spectroscopy, including the detection and characterisation of Earth-like exoplanets, and the Sandage Test, which aims to directly measure the acceleration in the expansion of the universe from the temporal variation of the redshift of extra-galactic sources.
Astronomers use high resolution spectrographs to record the pattern of colours received from distant objects, but the wavelength axes of these instruments can shift slightly over time, and so must be regularly calibrated with an external reference light source to ensure consistency between observations.
For several decades, lamps producing hundreds of narrow atomic emission lines have been used as calibration sources, but the high precision and accuracy demanded by exoplanet and cosmological observations now exceeds their capabilities.
In response, the astronomy community is turning to astrocombs, a laser technology giving a sequence of ultra-narrow, drift-free, regularly spaced optical frequencies on a selectable grid spacing of 5-50 GHz. When referenced to GPS time, astrocombs provide atomically traceable optical frequencies with a precision at the 10^-12 level.
Current astrocombs are complex and expensive systems, typically costing >2 million EUR, and their limited reliability requires regular maintenance visits by PhD-level staff.
Our proposal seeks to address these issues by developing a new, simple and robust laser platform based on diode-pumped Ti:sapphire. The timeliness of this concept is emphasised by letters of support from ESO, and from the HARPS3 and ANDES instrument consortia.
A promising proof-of-concept Ti:sapphire laser emerging from Heriot-Watt's current STFC consortium grant will first be systematically optimised to produce the powers and pulse durations needed for an astrocomb system.
Using new alignment and mounting techniques developed at Heriot-Watt it will then be developed into a turnkey device, in which the optical elements forming the laser cavity will be bonded directly to a common baseplate, eliminating the drift and instability associated with optomechanical mounts.
External partners will provide state-of-the-art nonlinear waveguides to the project, with designs tailored to generate broadband visible light when driven by the developed laser system. Using photonic locking and filtering methods, we will configure this light into the format needed for an astrocomb.
The final year of the project will integrate these diverse elements into a single astrocomb system, testing it first on a high resolution comb-mode-resolving spectrograph at Heriot-Watt.
We will conclude the project with a campaign at the 10-metre SALT telescope, validating the system outside the lab, as a key step to commercialisation and building community confidence in the performance of this disruptive astrocomb concept.
Steps towards commercialisation will be taken during the project including, where appropriate: filing of patent protection, spin-out company incorporation, development of licensing agreements, and input from business development advisors.
The project offers excellent value for money, with the £477K cost to STFC being highly leveraged by £187K in-kind support from our partners and £120K cash (20% FEC) from Heriot-Watt.
Almost 100 years later, some of the most exciting science cases for optical astronomy rely on spectroscopy, including the detection and characterisation of Earth-like exoplanets, and the Sandage Test, which aims to directly measure the acceleration in the expansion of the universe from the temporal variation of the redshift of extra-galactic sources.
Astronomers use high resolution spectrographs to record the pattern of colours received from distant objects, but the wavelength axes of these instruments can shift slightly over time, and so must be regularly calibrated with an external reference light source to ensure consistency between observations.
For several decades, lamps producing hundreds of narrow atomic emission lines have been used as calibration sources, but the high precision and accuracy demanded by exoplanet and cosmological observations now exceeds their capabilities.
In response, the astronomy community is turning to astrocombs, a laser technology giving a sequence of ultra-narrow, drift-free, regularly spaced optical frequencies on a selectable grid spacing of 5-50 GHz. When referenced to GPS time, astrocombs provide atomically traceable optical frequencies with a precision at the 10^-12 level.
Current astrocombs are complex and expensive systems, typically costing >2 million EUR, and their limited reliability requires regular maintenance visits by PhD-level staff.
Our proposal seeks to address these issues by developing a new, simple and robust laser platform based on diode-pumped Ti:sapphire. The timeliness of this concept is emphasised by letters of support from ESO, and from the HARPS3 and ANDES instrument consortia.
A promising proof-of-concept Ti:sapphire laser emerging from Heriot-Watt's current STFC consortium grant will first be systematically optimised to produce the powers and pulse durations needed for an astrocomb system.
Using new alignment and mounting techniques developed at Heriot-Watt it will then be developed into a turnkey device, in which the optical elements forming the laser cavity will be bonded directly to a common baseplate, eliminating the drift and instability associated with optomechanical mounts.
External partners will provide state-of-the-art nonlinear waveguides to the project, with designs tailored to generate broadband visible light when driven by the developed laser system. Using photonic locking and filtering methods, we will configure this light into the format needed for an astrocomb.
The final year of the project will integrate these diverse elements into a single astrocomb system, testing it first on a high resolution comb-mode-resolving spectrograph at Heriot-Watt.
We will conclude the project with a campaign at the 10-metre SALT telescope, validating the system outside the lab, as a key step to commercialisation and building community confidence in the performance of this disruptive astrocomb concept.
Steps towards commercialisation will be taken during the project including, where appropriate: filing of patent protection, spin-out company incorporation, development of licensing agreements, and input from business development advisors.
The project offers excellent value for money, with the £477K cost to STFC being highly leveraged by £187K in-kind support from our partners and £120K cash (20% FEC) from Heriot-Watt.
