Omni-SLR: a compact, low-cost, multi-purpose SLR system for the future expansion of global geodetic network

Omni-SLR: a compact, low-cost, multi-purpose SLR system for the future expansion of global geodetic network Toshimichi Otsubo ([email protected]) 1, Hiroshi Araki2, Yusuke Yokota3, Kenji Kouno3, Mihoko Kobayashi1, Takehiro Matsumoto4, Yusuke Nakamura3, Junichi Nakajima5, Haruna Furui6, Masaki Honda6, Shinobu Kurihara6and Yuichi Aoyama7 1: Hitotsubashi Univ, 2: NAOJ, 3: IIS/Univ of Tokyo, 4: JAXA, 5: Softbank Corp., 6: GSI, 7: NIPR IAG Scientific Assembly 2025, Rimini, 4 Sept 2025 G06-2: Global geodetic infrastructure for Earth System Monitoring A story of challenges: What can be done by a very minimum & simple SLR system? Very Low-cost Hardware: net 50-60k EUR/USD. Key components = COTS. Very Compact High mobility < 100 kg. Low energy consumption < 100 W. Multi-purpose Primary: SLR. Linked with various applications (time transfer, space comm, 6G airborne comm, etc). Omni-SLR: new attempts for SLR Envisaging that… new countries/institutes can own and operate SLR stations. the SLR global network and the products are drastically enhanced. the SLR optical tracking/ranging technologies are more versatile. SLR Targets: monotonically increasing SLR Stations: almost the same A bit more expensive in 2025 Omni-SLR: key components (as of 2025) CryLAS FDSS532-Q2 λ = 532nm; pulse width = 1.06 ns; Rep. rate = 10 kHz; output = 5.7 μJ Sync output; int/ext trigger mode (RX) Kasai GS-200RC Hamamatsu Photonics C11202-100 Ritchey–Chrétien Φ = 203 mm; f = 1624 mm Aperture = 100 µm; Efficiency = 70%; Dark noise = 30 cps; No gate control Swabian Instruments TimeTagger Ultra (Value Ed) 4 ch (ch1 = start; ch2=stop; ch3=1PPS) 42 ps RMS 70 M events/sec Furuno TB-1 GNSS OCXO 10 MHz: ~ 5 x 10^-11 @ 1s 1 PPS: ~ 40 ns Vixen AXJ Mount (Eq.) Converted to Alt-Az Load: 22 kg max Vaisala PTB-330 3 sensor barometer 0.2 hPa per sensor Link budget calculation (simplified) Herstmonceux (UK) Omni-SLR (ver 2025.2) =0.2 0.5 Telescope diameter 2 m Φ Laser output 0.03 1.0 W 1 mJ, 1 kHz 0.006 mJ, 5 kHz 0.005 1 Hx applies ND 2 or 3 (1/100 or 1/1000) for LEO, and still gets 1000 returns/NP. Omni-SLR: reversing the trend? Laser Pulse Width 1 ns 100 ps 10 ns 10 ps Laser Repetition Rate 1 pps 0.01 pps 100 pps 10k pps Early days 1960’s 70’s 20 ns to 1 ns 0.1 to 1 pps “kHz” 2000s30—10 ps 2 kpps Traditional “Hz” 1990s100 ps 5—10 pps Omni-SLR 2020s 1 ns 10 kpps 1 ns pulse width laser useless for mm geodesy? Expected NP precision assuming white noise 1 return/NP: ~ 7 cm 10 returns/NP: 2-3 cm 100 returns/NP: ~ 7 mm 1000 returns/NP: 2-3 mm 10000 returns/NP: ~ 0.7 mm Accept random error but Manage systematic error Omni-SLR: conveyable by a car TX RX AT1 AT2 Mount Detector Omni-SLR: project status GNSS x 2 VLBI Gravimeters Omni-SLR being developed by the team of (PI: T Otsubo) being supported by: •GGOS Japan (see B Miyahara’s talk later today). •the national institutes such as GSI, NIPR, NICT, Japan Coast Guard and JAXA. •private companies in the fields of telecommunications and heavy industries. 2020-2023 First successful budget hunting (Kakenhi) followed by various joint research projects 2020 Concept design 2021 Component tests 2022 Assembly tests 2023 Field test at NIPR Tachikawa 2024 CDP Number 7317 95 01 assigned 2024 DOMES Number 21791M008 assigned 2024 Field test at GSI Ishioka 2025 First data release to ILRS 2026-2027 First Antarctica SLR test at Syowa Rooftop of National Institute of Polar Research, Tachikawa, Tokyo H-maser 2023-12-22 SARAL & SWARM-C 2023-12-26 BEACON-C & SWARM-C Rooftop of National Institute of Polar Research, Tachikawa, Tokyo Omni-SLR First Returns: SARAL 9:32 UT, 22 Dec 2023 Compromise(?) due to miniaturisation and low prices Low link budget Small-size telescope and compact laser. About 1% of today’s first-class stations. Large single-shot RMS 1 ns pulse width 7 cm single-shot RMS. About 10 times larger than others. No range-gate generator High-rate noise points all entering the event timer. Unstable tracking performance Vixen AXJ mount: designed for astrography, payload < 22 kg, lightweight alminum Periodic motion, limited angular speed, unknown tracking error. Open-air condition Not suitable for laser and timing devices; sometimes harsh for operators Compromise(?) due to miniaturisation and low prices Low link budget Small-size telescope and compact laser. About 1% of today’s first-class stations. Large single-shot RMS 1 ns pulse width 7 cm single-shot RMS. About 10 times larger than others. No range-gate generator High-rate noise points all entering the event timer. Unstable tracking performance Vixen AXJ mount: designed for astrography, payload < 22 kg, lightweight alminum Periodic motion, limited angular speed, unknown tracking error. Open-air condition Not suitable for laser and timing devices; sometimes harsh for operators 1% ret rate for LEO. LAGEOS possible. Always single photon. subcm NP precision for LEO with > 100 returns. Software (c++) range gate works. Low-cost mount works! Won’t decrease # of NPs. Short cables, short delay. Key parts to be shielded. Omni-SLR QC’ed https://doi.org/10.1186/s40623-016-0447-8 https://geo.science.hit-u.ac.jp/slr/bias/ Applying our POD quality check •Hitotsubashi Univ’s bias reporting system (Otsubo et al, J Geod, 2019) applied to the spherical satellite SLR (Starlette, Stella, Ajisai etc) of Ishioka data. •Pass-by-pass quality as good as other ILRS stations for LEOs (several cm). •Sufficient LAGEOS data needed for 1 cm level quality check 19 # 7317 = ISHIOKA # sat site date time dur rb mm error tb us error prec bad total rms pres temp hum sdelay shft r STEL 7317 2025/02/14 11:21 0 -27 ( 48 ) -------.- ( ----.- ) 19 0 / 2 80 1001.8 277.9 44 3155 0 63 AJI1 7317 2025/02/26 19:07 5 -11 ( 43 ) - 2.1 ( 11.7 ) 9 0 / 11 81 1003.5 278.9 38 3154 0 65 STRL 7317 2025/02/26 20:25 1 -111 ( 7 ) -------.- ( ----.- ) 1 0 / 4 65 1004.1 279.0 38 3153 0 66 AJI1 7317 2025/02/27 18:14 4 -34 ( 85 ) - 0.7 ( 20.9 ) 14 0 / 8 84 1006.9 277.9 72 3150 0 62 LAG1 7317 2025/02/27 19:47 0 ------ ( ----- ) -------.- ( ----.- ) ----- 0 / 1 60 1007.4 278.1 74 3150 0 62 AJI1 7317 2025/03/13 19:45 5 96 ( 24 ) 9.1 ( 8.9 ) 6 0 / 12 85 996.3 287.7 67 3146 0 6 AJI1 7317 2025/03/14 16:52 2 -25 ( 24 ) -------.- ( ----.- ) 20 0 / 4 93 1011.0 277.1 50 3149 0 64 AJI1 7317 2025/03/14 18:52 8 50 ( 12 ) - 3.9 ( 5.0 ) 11 0 / 17 83 1005.8 279.6 44 3149 0 63 STEL 7317 2025/03/17 10:51 6 - 7 ( 20 ) 13.6 ( 5.2 ) 7 0 / 12 64 994.9 279.7 43 3147 0 62 STRL 7317 2025/03/17 11:55 0 46 ( 50 ) -------.- ( ----.- ) 7 0 / 2 58 996.0 278.9 46 3147 0 63 AJI1 7317 2025/03/17 12:01 4 51 ( 26 ) - 8.2 ( 11.5 ) 5 0 / 9 79 996.1 278.8 47 3147 0 63 AJI1 7317 2025/03/17 14:05 7 - 49 ( 17 ) 0.5 ( 6.4 ) 7 0 / 14 82 997.7 277.8 50 3147 0 64 AJI1 7317 2025/03/21 10:27 7 59 ( 15 ) - 7.0 ( 6.2 ) 7 0 / 12 80 995.9 284.3 57 3148 0 63 STEL 7317 2025/03/21 10:46 3 12 ( 27 ) 13.1 ( 8.7 ) 6 0 / 6 62 996.0 284.2 59 3148 0 6 STRL 7317 2025/03/21 11:22 1 -54 ( 15 ) -------.- ( ----.- ) 3 0 / 5 63 996.1 283.8 63 3148 0 63 AJI1 7317 2025/03/21 12:26 8 -17 ( 16 ) - 6.6 ( 4.8 ) 11 0 / 13 82 995.9 282.9 68 3147 0 63 AJI1 7317 2025/04/07 11:21 5 -26 ( 19 ) - 3.5 ( 9.9 ) 10 0 / 11 78 1002.3 282.5 81 3150 0 63 STEL 7317 2025/04/07 11:36 1 71 ( 29 ) -------.- ( ----.- ) 5 0 / 3 62 1002.4 282.2 82 3150 0 63 STRL 7317 2025/04/07 13:18 0 ------ ( ----- ) -------.- ( ----.- ) ----- 0 / 1 65 1002.1 282.9 78 3149 0 63 AJI1 7317 2025/04/08 10:27 7 - 68 ( 14 ) 17.6 ( 6.4 ) 14 0 / 13 82 994.6 286.4 73 3153 0 65 LARS 7317 2025/04/09 10:10 0 ------ ( ----- ) -------.- ( ----.- ) ----- 0 / 1 72 999.6 286.1 59 3154 0 63 STEL 7317 2025/04/09 10:41 3 4 ( 38 ) 8.7 ( 12.2 ) 8 0 / 6 59 1000.9 284.7 66 3154 0 6 AJI1 7317 2025/04/09 11:40 3 - 44 ( 46 ) 8.1 ( 19.1 ) 7 0 / 5 82 1001.6 283.9 70 3154 0 63 STRL 7317 2025/04/09 12:04 1 -49 ( 23 ) -------.- ( ----.- ) 5 0 / 5 65 1001.7 284.1 70 3152 0 62 AJI1 7317 2025/04/14 11:07 12 12 ( 19 ) - 18.4 ( 5.7 ) 13 0 / 10 82 986.4 287.9 52 3153 0 63 STEL 7317 2025/04/14 11:47 0 -50 ( 14 ) -------.- ( ----.- ) 2 0 / 3 61 986.6 287.4 56 3153 0 63 AJI1 7317 2025/04/14 13:09 6 -69 ( 38 ) - 26.7 ( 10.7 ) 7 0 / 10 79 986.8 286.2 81 3154 0 64 AJI1 7317 2025/04/17 10:27 10 14 ( 11 ) - 10.0 ( 3.7 ) 6 0 / 19 86 998.6 290.2 62 3154 0 64 STEL 7317 2025/04/17 12:08 1 2 ( 141 ) -------.- ( ----.- ) 199 0 / 2 56 999.5 288.5 69 3153 0 63 AJI1 7317 2025/04/17 12:30 7 - 17 ( 13 ) - 6.7 ( 5.1 ) 9 0 / 14 86 999.7 288.4 69 3153 0 63 Large single-shot scatter NP scatter smallerPass-by-pass range bias Summary Record-low cost SLR, but this is not a toy. •Not at the level of today’s first-class stations, but works as an SLR system. •First success at NIPR Tachikawa. Data from GSI Ishioka being sent to ILRS. •Also for non-geodetic purposes (satellite/airborne comm., time transfer, etc.). •See Y Yokota’s talk (H-01) for Omni-SLR timing measurement. Future works •Improve the efficiency and rigidity of the optical parts. •More SLR data →to be verified by local tie survey at Ishioka, Oct 2025. •Further quality control to enhance stability. •Daytime ranging and daytime-only star calibration. •Stronger link: higher-power laser & larger telescope (balanced with cost) •Antarctica (Syowa) test planned Jan–Feb 2027 •Simplified procedures, remote operation and automation Antarctic test approved NIPR Pioneering Research Project “Development of a compact SLR system for the first antarctica experiment” 3 years: FY2024 to FY2026. Syowa: 69S 35E. FY2024-FY2025 Preliminary tests in Japan. FY2025 A roll-off roof container to be installed at Syowa (if possible). FY2026 (JARE68) Shipped to Syowa (Nov 2026). SLR test at Syowa (Jan-Feb 2027). → Syowa’s container = 3.0 m x 2.4 m