Abstract Details
| Name: Tanya Das Affiliation: Indian Institute of Astrophysics Conference ID: ASI2018_1571 Title : Development of a Fabry-Perot etalon stabilization system for Doppler Spectroscopy Authors and Co-Authors : Ravinder K. Banyal, S. Kathiravan, T. Sivarani, B. Ravindra; Indian Institute of Astrophysics, Bangalore-560034. Abstract Type : Poster Abstract Category : Instrumentation and Techniques Abstract : Accurate wavelength calibration is an important factor for any measurement with high resolution spectrographs. Stellar spectrum comprises of discrete absorption or emission lines whose position is precisely determined by calibrating the spectrographs using known reference lines generated from laboratory sources. For the spectrograph to measure small variations in Doppler shift, the wavelength calibration must be sufficiently stable during observation time. Instrument instability, mainly due to environmental factors like temperature and pressure variations, and limitations of traditional calibration methods, for example Th-Ar lamps, are the two challenges which bound high precision spectroscopy. Through proper environmental control, by maintaining pressure at 1 mbar and temperature fluctuations at ±0.05 ˚C, Fabry Perot etalon (FP) can yield a velocity precision of 1-10 m/s, when used for wavelength calibration. We aim to develop a FP based wavelength calibrator which is both passively and actively stabilized. The FP etalon, along with the illumination and collection optics will sit inside an evacuated and temperature controlled chamber and this is termed as passive calibration. A stable mounting scheme for holding the FP unit along with related optics is required. For this purpose, we have designed two different mounting schemes, a cage based mounting scheme and a rail based mounting scheme. Enclosure temperature is being controlled using a Proportional-Integral (PI) controller developed in house. Preliminary tests have been conducted to test the pressure and temperature stability achieved by our system. The final wavelength solution model developed, can be used for generation of precise wavelength map and PSF map for the spectrograph. |