The Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) is the main instrument on-board the SCISAT-1 satellite, a mission mainly supported by the Canadian Space Agency . It is in Low- Earth Orbit at an altitude of 650 km with an inclination of 74E. Its data has been used to track the vertical profile of more than 30 atmospheric species in the high troposphere and in the stratosphere with the main goal of providing crucial information for the comprehension of chemical and physical processes controlling the ozone life cycle. These atmospheric species are detected using high-resolution (0.02 cm-1) spectra in the 750-4400 cm-1 spectral region. This leads to more than 170 000 spectral channels being acquired in the IR every two seconds. It also measures aerosols and clouds to reduce the uncertainty in their effects on the global energy balance. It is currently the only instrument providing such in-orbit high resolution measurements of the atmospheric chemistry and is often used by international scientists as a unique data set for climate understanding.
The satellite is in operation since 2003, exceeding its initially planned lifetime of 2 years by more than a factor of 5. Given its success, its usefulness and the uniqueness of the data it provides, the Canadian Space Agency has founded the development of technologies enabling the second generation of ACE-FTS instruments through the High Vertical Resolution Measurement (HVRM) project but is still waiting for the funding for a mission.
This project addresses three major improvements over the ACE-FTS. The first one aims at improving the vertical instantaneous field-of-view (iFoV) from 4.0 km to 1.5 km without affecting the SNR and temporal precision. The second aims at providing precise knowledge on the tangent height of the limb observation from an external method instead of that used in SCISAT-1 where the altitude is typically inferred from the monotonic CO2 concentration seen in the spectra. The last item pertains to reaching lower altitude down to 5 km for the retrieved gas species, an altitude at which the spectra are very crowded in terms of absorption. These objectives are attained through a series of modification in the optical train such as the inclusion of a field converter and a series of dedicated real-time and post-acquisition algorithms processing the Sun images as it hides behind the Earth. This paper presents the concepts, the prototypes that were made, their tests and the results obtained in this Technology Readiness Level (TRL) improvement project.
The Canadian satellite SCISAT-1 developed for the Canadian Space Agency in the context of the ACE mission
(Atmospheric Chemistry Experiment) was launched in August 2003. The mission has been a tremendous technical and
scientific success. The main instrument of the ACE mission is a high-resolution Fourier Transform Spectrometer (FTS)
designed and built by ABB Bomem. Several new missions are currently considered as follow-on to the ACE mission to
ensure continuity of the extensive high-quality data set of the Earth's atmosphere that was started with the ACE mission,
but also possibly to bring new improvements and enhance the utilization of these data. A solar-occultation FTS based on
the optical design for ACE-FTS, has been selected for a planetary exploration mission to measure the atmospheric
composition of Mars that will launch in 2016.
An overview of these different missions will be presented. The need for technological evolutions will be examined for
each mission. Some evolutions imply only minor changes, for example, to cope with some parts obsolescence. Others
will require increasing instrument capabilities compared to those of the ACE instrument. These different technological
evolutions will be presented.
Ultrashort laser pulses are very promising tools for performing accurate dissection in the eye, especially in the corneal stroma. The development of eye femtosurgery requires basic knowledge about laser-tissue interaction. One of the most significant parameters is the ablation threshold, the minimal laser energy per unit surface required for ablation. We present here measurements of the femtosecond laser ablation threshold as a function of the pulse duration for two cornea layers (epithelium and stroma) using optical damage diagnosis. Experiments have been realized with the INRS Ti:Sapphire laser (60 fs-5000 fs, 800 nm, 10 Hz). Our experimental results are fitted with a model for laser-matter interaction in order to determine some intrinsic physical parameters
In 1985, the discovery of chirped-pulse amplification (CPA) by G. Mourou and D. Strickland led to ultrashort and high energy pulse lasers. Since energy deposition of ultrashort pulses occurs with limited heat transfer and damages, potential applications of femtosecond lasers to corneal surgery are very promising. By focusing a femtosecond laser on a solid surface, matter is ablated and this process is strongly laser parameter dependent. The goal of the experiment presented here was to measure the femtosecond laser ablation thresholds for different corneal layers and hydrogels. Experiments have been realized with the INRS Ti:Sapphire laser (60fs-400ps, 800nm, 10Hz) and they constitute an initial step toward the development of a new type of high precision surgical tool for corneal microsurgery. Results will be compared to theoretical calculation for light-tissue interaction and propagation using the hydrodynamic code developed at INRS. Grant Identification: NSERC, FRSQ Research in Vision Network and China Scholarship 22836034.