1. Feasibility of Optical Wireless transmission systems for CTA R. Corsini, A. Wajahat, E. Ciaramella Scuola Superiore Sant’Anna, TeCP, Pisa, Italy R. Paoletti University of Siena and INFN Pisa, Italy INFIERI Workshop, Madrid, Jan. 27 th – 29 th 2014

2. Outline Motivation Optical wireless transmission system for CTA telescope Draft Requirements Open issues Draft activity list Conclusions and future perspective

3. INFIERI Workshop, Madrid, Jan. 20 th – 22 th, 2014 SiPM camera for SST (Small Size Telescope) Design of SST for CTA (Cherenkov Telescope Array) Single mirror Dual mirror In dual mirror design the focal plane is curved (spherical shape) In camera design a specific solution for curved-planar transition is needed

4. INFIERI Workshop, Madrid, Jan. 20 th – 22 th, 2014 SiPM camera for Small Size Telescope Example: CHEC (Compact High Energy Camera ) camera for SST telescope Curved sensor plane Flat design for digitizer section and backplane Transition Done with ribbon cables Near photo-sensors, decouples sensors+front end electronics from digitizers and backplane

5. INFIERI Workshop, Madrid, Jan. 20 th – 22 th, 2014 SiPM camera for SST telescope Curved focal plane Readout modules based on analog digitizers Transmit digital data to backplane electronics Exploit wireless optical transmission to match modules to flat backplane

6. INFIERI Workshop, Madrid, Jan. 20 th – 22 th, 2014 Motivation Main issues of the existing design Transition between curved and flat surface done by ribbon cable Needs of reduction of electrical interconnections Needs of stress-free module placement Proposed solution Optical wireless technology to connect sensors on the curved surface with the flat layer of the backplane avoiding data transmission cables

7. INFIERI Workshop, Madrid, Jan. 20 th – 22 th, 2014 Example of proposed solution Alternative topology can be exploited

8. INFIERI Workshop, Madrid, Jan. 20 th – 22 th, 2014 Optical Wireless Communications Characteristics No EMI with radio systems, no “e-smog” Available and unregulated spectrum Simple shielding by opaque surfaces → easily obtainable privacy Flexibility of placement Small form factor Components (laser, PIN diode, electronics) available at low cost and high reliability from telecom world Motivation

9. INFIERI Workshop, Madrid, Jan. 20 th – 22 th, 2014 DRAFT REQUIREMENTS: Bit rate = 100 Mbit/s, burst mode, 8B10B coded L = 2 mm- 2 cm Environmental requirements: outdoor Power consumption? Mechanical dimensions? Mechanical and optical alignment tolerances? Reliability requirements (life time, FIT, MTBF)? Target Cost ……….. Feasibility of Optical Wireless transmission systems at CTA

10. INFIERI Workshop, Madrid, Jan. 20 th – 22 th, 2014 Open issue: Wavelength? Source type? Receiver Type and dimensions? Package type? Collimating Lens (material)? Optical alignment and tolerances? Power supply? Feasibility of Optical Wireless transmission systems at CTA

11. INFIERI Workshop, Madrid, Jan. 20 th – 22 th, 2014 Draft activity list Specifications definition Optical and Electrical/Electronic design Components/sub systems specification definition Components/sub systems selection and acquisition Components/sub systems characterization Prototype assembly and testing ……………

12. INFIERI Workshop, Madrid, Jan. 20 th – 22 th, 2014 Conclusions Optical wireless is a viable solution for connection and transition between the curved surface topology of the sensors layer and the flat surface topology of the backplane layer. No show stopper found at a first analysis There are several challenges to integrate an optical wireless system on a Small Size Telescope for CTA in spite of its numerous advantages

13. INFIERI Workshop, Madrid, Jan. 20 th – 22 th, 2014 THANK YOU r.corsini@sssup.it