Raman Laser Spectrometer (RLS) is one of the Pasteur Payload instrument of the ExoMars 2020 mission, within the ESA’s Aurora Exploration Program. RLS is mainly composed by SPU (Spectrometer Unit), iOH (Internal Optical Head), and ICEU (Instrument Control and Excitation Unit), and will analyse Mars surface and sub-surface crushed samples by Raman spectroscopy. For the RLS Flight Model (FM) verification campaign, an end-to-end quick functional test was developed to evaluate the instrument performances stability. This test consists on a comparison of the centre pixel and the FWHM (Full Width at Half Maximum) of a set of Ne calibration lamp peaks, and was decided to be done before and after ever risky activity (transport, thermal tests, etc.) In the course of the end-to-end functional test carried out on RLS FM as part of the pre-delivery checks, an increment on the FWHM calibration lamp peaks was observed. Such performance variation was also noted to be dependent on the way the SPU thermal strap was assembled and the environmental conditions (P and T) in which the spectra were acquired. For that reason, a new SPU thermal strap assembly procedure was decided to be designed in order to ensure no extra negativeeffect was going to appear during the RLS FM installation on the ALD (Analytical Laboratory Drawer) and the instrument flight operation. In this paper, a deep exploration of the conditions in which such “de-focus” (probably due to an excessive thermal gradient between SPU structure and CCD) appears is carried out, demonstrating that the new thermal strap assembly procedure minimizes an incidental extra de-focus appearance during RLS installation on the ALD.
Raman Laser Spectrometer (RLS) is the Pasteur Payload instrument of the ExoMars mission, within the ESA’s Aurora Exploration Programme, that will perform for the first time in an out planetary mission Raman spectroscopy. RLS is composed by SPU (Spectrometer Unit), iOH (Internal Optical Head), and ICEU (Instrument Control and Excitation Unit). iOH focuses the excitation laser on the samples (excitation path), and collects the Raman emission from the sample (collection path, composed on collimation system and filtering system). Its original design presented a high laser trace reaching to the detector, and although a certain level of laser trace was required for calibration purposes, the high level degrades the Signal to Noise Ratio confounding some Raman peaks. So, after the bread board campaign, some light design modifications were implemented in order to fix the desired amount of laser trace, and after the fabrication and the commitment of the commercial elements, the assembly and integration verification process was carried out. A brief description of the iOH design update for the engineering and qualification model (iOH EQM) as well as the assembly process are briefly described in this papers. In addition, the integration verification and the first functional tests, carried out with the RLS calibration target (CT), results are reported on.