Ivan Procházka Josef Blažej, Jan Kodet presented at : ELT meeting CTU in Prague, December 8, 2010 Czech Technical University in Prague, Czech Republic Status of the European Laser Timing ELT Detector package

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Principal participants and contributors n Luigi Cacciapuoti, ESTEC, The Netherlands ESA coordination n Urs Hugentobler, Tech. Univ. Munich, Germany space geodesy n Pierre Lauber, TU Munich, Germany Satellite Laser Station Wettzell n Ivan Prochazka, Czech Tech.University in Prague Instrument Science coordinator n Wolfgang Schaefer, TimeTech, Germany timing devices n Ulrich Schreiber, Tech.Univ.Munich & BKG Germany Data Analysis Coordinator

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 ACTIVITIES in SPACE RELATED PROJECTS Czech Technical University in Prague new ESA member since 2008 n Satellite Laser Ranging since 1972 n Picosecond Detector Technology since 1984 n Planetary altimetry & LIDAR since 1989 n Picosecond Event Timing since 1996

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Satellite Laser Ranging Since 1972, world 3rd country

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Satellite Laser Ranging operation principle pulsed optical radar range precision / mm / shot operational range ooo km 25 installations on on 5 continents Graz, Austria

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Single Photon Detectors made by CTU Si,200 um,TE3 cooled, vacuum GaAs messa GaAsP, 350 um Detector for LTT China Complete detector packages 130 mm

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Detectors for Space Applications CTU Prague & IKI Moscow MARS 92 (USSR / Russia, )Photon counting laser rangefinder Mars baloon altimetry NASA Mars Polar Lander, (USA, 1998)Photon counting LIDAR, Mars surface atmospheric studies S.P.Pershin et all, IKI Russia

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Laser Time Transfer in Space n LTT – China since April 2007 China Compass-M1 / Beidou n T2L2 CNES - France since June 2008 JASON-2 n Time and frequency transfer using ps laser pulses in space n Relying on available technology and ground segment Satellite Laser Ranging n Superb precision and accuracy n Navigation, deep-space, fundamental physics… E.Samain

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 n “H maser in space”, ’94, France + Russia + Prague canceled n LTT China + Prague Compass M1 Beidou, (operational since Aug. 2007) n T2L2 E. Samain et al ACES -> Miriade -> Jason 2 (operational sine June 2008) n ELT proposed by CTU Prague and TU Munich, June 2008 I.Prochazka, U.Schreiber n Investigators Working Group established Dec n Ground tests (Prague, Munich) startedDec European Laser Time Transfer ELT History review

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 n “H maser in space”single photon detection, 100 um SPAD, gated n LTT China single photon detection, 25 um SPAD, not gated + very simple design and construction - modest precision and accuracy ~30 ps - synchronous operation needed /solved/ n T2L2 multiphoton, time walk corrected, asynchronous + extremely high precision, asynchronous operation - very high complexity, systematic errors issue n ELT single photon det.,100 um SPAD, gated, temp. comp. + high precision AND accuracy, simple, compact +/- synchronous operation needed /solved/ Laser Time Transfer - Concepts

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 ELT space optical part concept Laser retro array, GFZ concept existing, approved Detector input aperture Photon detection chip Detector optics n NO optical components alignment n Very simple and rugged

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Specific accomodation requirements # 1 n Field of view of the optical assembly (retro + receiver) + / - 60 degrees from nadir un-obscured view n Detector temperature range - IDEAL caseany temperature C, stable +/- 2 C - the WORST caserange -50…+50 C n Cooling of optical receiver - total heat generated 0.15 W to 5 W depends on configuration - amount of heat depends on detector temperature range (the excess heat is used to temp.stabilize the receiver, if needed) n = > KEY PROBLEM AREA – THERMAL CHANGES of ELT assempbly

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Wettzell ground demonstration experiment December 2008 – May 2009 Ground demonstration of the entire timing performance via a space target and SLR combined

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Wettzell ground demonstration experiment December 2008 – May 2009

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Wettzell ground demonstration experiment n The experiment feasibility was demonstrated in a complete ground experiment n The final precision was impaired by in-appropriate WLRS laser pulse length problem. ( about 230ps instead of 80 ps). n The indoor tests indicate, that for shorted laser pulses the desired precision might be reached.

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Precision and accuracy goals ELT detector assembly n Single photon signals only = > no biases assured by useful data rate ( < 20%) n Detection delay jitter< 30 ps rms resulting in 3 ps / 100 s n Detection delay stability+/- 3 ps

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Prague group activities - detector n Detector package for WLRS # 1 (delivered) # 2 (reference) n Development of the ELT package u Version 1.0CMOS, very low powerOK u 1.1 Bias voltage / temperature compensation OK u 1.2. Temperature drift compensation in progress n Detection absolute delay determinationpromissing n Contribution to WLRS experiment n Long term stability tests / SLR Graz /OK

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Development of the ELT package Version 1.0CMOS, low power n CMOS version, low power < 50 mW (detector) < 500 mW (power s.) n Ver Bias voltage / temperature compensation OK detector bias controlled within the temp. range of -50… +50 C

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Development of the ELT package Version 1.1.CMOS, low power n Detection delay dependence ~ 60 ps / V at 2.5 V ab = > +/- 3 ps delay stability using bias stabilizing circuit n Timing jitter 1.5 V above 48 ps laser pulse

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Detection absolute delay determination n Analysis of the individual contributors u Photon - > electron conversion? << 1 ps u Semiconductor propagation? 1 ps u Avalanche build upOK u Electronic Detection mechanismOK n Avalanche build up1.125 ns +/- ?? n Electronic detection mech.8 ps / 1 mV threshold det. n Electronics propagation5.300 ns +/- 7 ps n Independent comparison checks required

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Detector package operation in extreme background regime n Operational up to 200 Mc /s of background photon flux (up to 50 Mc/s are expected) n Gated 100 ns before simulation of ELT daylight operation n Timing jitter < 25 ps rms overall using 48 ps laser pulse n Detection delay stability +/- 4ps over entire background dynamical range

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Timing stability of the photon counting chain Graz SLR station, SPAD detector n NOTE system STABILITY~ 2.5 ps r.m.s. Cable temp.drift ~ 1 ps / K n = > The /cables/ temperature issue is critical for timing stability Cables ~ meters are expected to be locate outside.

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 Development of the ELT package Version 1.2.CMOS, temperature drift compensation n The new detector electronics is automatically compensating the temperature variations of the detector electronic circuit delay including the delay temperature drift of the (long) signal cables n The operation requires Gate ON pulses synchronously with the local time scale

I.Prochazka, ACES IWG Observatoire de Paris, Paris, July 9, 2009 n WLRS experiment u The experiment indicated the feasibility of the ELT u The resulting precision/accuracy goal was has not been met yet due to unexpected problems with Wettzell hardware (laser pulse) u The experiment continues n The development of the ELT detector package in Prague u Version 1.0CMOS, low powerOK u 1.1 Bias voltage / temperature compensation OK u 1.2. Temperature drift compensation in progress u Long term detector stability tests / SLR Graz /OK Actual status of SPAD detector development for ELT-ACES CONCLUSION