Fabry - Perot Interferometer Prototype

A new Fabry-Perot Interferometer has been developed for the ADAHELI ADvanced Astronomy for HELIophysics solar satellite mission at the “Tor Vergata” University Solar Physics Laboratory. Fabry-Perot narrow filters are of great interest for the study of extended astronomical sources, such as the solar photosphere and chromosphere. The prototype instrument provides a high throughput that allows for the necessary high time-resolution for observing fast dynamic processes. Dedicated software has been developed in order to control both the coarse and fine piezo-actuated movements, allowing for fast (1ms) tuning capabilities and nano-positioning. The general mechanical behavior has been tested for use at the focal plane of a new space-qualified prototype but the design is also suitable for use in ground-based telescopes. The technology owner is looking for collaborative manufacturing/development of the technology for both space or land based solar telescope applications. Description A Fabry-Perot (FP) is an instrument based on multiple beam interferometry. It consists of two high reflectivity flat plates that create an optical cavity in which an incoming beam undergoes multiple reflections. The constructive interference and the consequent wavelength selection depend on the optical path difference, i.e. on the gap spacing d between the plates. In this way, the interferometer allows transmission of light at well-defined wavelengths. A spectrometer based on tunable filter is a solution to the modern spectroscopy problem of collecting both spatial and spectral information. Every image acquired is nearly monochromatic and it is possible to rapidly change the wavelength of the observation by varying the gap width. Fabry-Perot tunable filters are of exceptional interest in high spectral resolution imaging for both ground-based and space applications since they allow the scanning of spectral lines in an extended range of wavelengths. The prototype presented here has been developed as part of the study for the narrow band channel of the ADAHELI mission. The ADvanced Astronomy for HELIophysics (ADAHELI) is a solar satellite designed to investigate the dynamics of solar atmosphere as part of the Italian Space Agency (ASI) program. A proposal based on ADAHELI was submitted to ESA S-class Mission 2012 Call. The prototype design presented here provides a high achievable spectral resolution, rapid wavelength tuning (through piezo-scanning), and high stability (through both capacitance and thermal stabilisation systems). Innovations and advantages of the offer The design of the test prototype is based on two concepts: ease of manufacture and modularity. The optomechanics of the laboratory prototype has been designed to house: a 1inch (2.54 cm) optical cavity, three micrometers, three piezoelectric actuators, and three high sensitivity capacitive sensors. The adopted opto-mechanics has to control and guarantee the parallelism of the etalon optical surfaces during the wavelength scan, within the optical tolerances defined above. The etalon main dimensions are: external diameter = 2.54 cm, thickness of the optical surfaces = 15 mm. Maximum displacements are 12 mm for micrometers and 15 μ m for piezoelectric actuators. The high sensitivity capacitive sensors working distance is 50 μm. A dedicated controller, calibrated on the selected piezoelectric actuators and capacitive sensors, manages the control loop. Further Information Fabry-Perot Imaging Spectroscopy, nanopositioning, optical qualification. Application Current Applications  Space-based solar observation  Earth based solar observation  Earth observation  Astronomy  Spectro-polarimetry Potential Applications  LIDAR  ITC systems Comments on the technology by the broker ADAHELI ADvanced Astronomy for HELIophysics is a solar satellite designed to investigate the fast dynamics of the solar photosphere and chromosphere performing visible and NIR broad-band and monochromatic observations of selected atomic lines. ADAHELI is an Italian Space Agency (ASI) project, approved for a feasibility study within the ASI Small Missions call. ISODY Interferometer for SOlar DYnamics is a Gregorian telescope and its focal plane suite (FPS). The FPS is composed of a high-resolution fast acquisition system, based upon a tandem of Fabry-Perot interferometers operating in the visible and NIR regions on selected solar atmospheric lines, a broad band channel, and a correlation tracker used as image stabilization system. The Fabry-Perot etalon prototype, based on the capacitance-stabilised concept, realized in the Tor Vergata laboratory, has been developed to perform preliminary mechanical and optical tests with a view to a future Fabry-Perot etalon prototype for space application. Description of Space Heritage Technology developed for ADAHELI (Advanced Astronomy for HELIOphysics) small satellite mission. Aim of ADAHELI Mission is investigating Sun photospheric and chromospheric dinamics performing observations in VIS-NIR bands and solar radiance by acquisitions in the millimetric bands. Giovannelli, L. et al., Testing of the "Tor Vergata" Fabry-Pérot interferometer prototype, Proc. SPIE, 8446, 84463Q, 2012 Berrilli,F. Et al. The Fabry-Perot interferometer prototype for the ADAHELI solar small mission, Proc. SPIE, 8148, 814807, 2011 Greco, V.; Cavallini, F.; Berrilli, F., Future instrumentation for solar physics: a double channel MOF imager on board ASI Space Mission ADAHELI, Astrophys.&S.S., 328, 313, 2010 This technology description was downloaded from www.esa-tec.eu