MTG FCI VISIBLE DETECTOR DETECTION CHAIN DESCRIPTION AND PRELIMINARY RESULTS

Transcription

1 DOC-TAS-FR-003 MTG FCI VISIBLE DETECTOR DETECTION CHAIN DESCRIPTION AND PRELIMINARY RESULTS TAS: S Demiguel, T Gilbert, JL Canaud, A Artinian T Dartois ESA: M Wilson ICSO Tenerife, Canary Islands, Spain, 7-10 October 2014

2 Outline 2 Detector chain description and main specifications BBM Tests description Preliminary results

3 Meteosat Third Generation (MTG) Flexible Combined Imager (FCI) MTG: ESA program TAS prime 3 TAS also responsible of: FCI instrument Detection subsystems Detector assemblies Video Chain Units Mission overview Earth image cycle : 10 mn based on N/S and E/W single scan mirror. 16 spectral channels with a resolution between 0.5 and 2km.

4 Detectors block 4 5 visible channels in 1 detector assembly based on CMOS technology (Contractor e2v) working in snapshot mode at high frame rate (~2.65kHz) and high pixel frequency (~4MHz) 11 infrared channels in 4 detector assemblies based on HgCdTe material hybridized on CMOS ROIC circuit.

5 CMOS choice versus CCD Motivations: True Snapshot function with direct access to the pixel level, Lower consumption, interfaces simplifications and higher radiation tolerances Similar electrical CMOS interfaces characteristics as IR detectors Pixel selection functions to manage the operability 5 TAS heritage: CNES R&T: Imager snapshot 2k 2k and 4k 4k CMOS TDI demonstrators ESA R&T: Back-Illuminated Thinned CMOS imager Focal Plane (BITFPA) European High Flux CMOS Image Sensor 4M pixels 16M pixels CMOS snapshot

6 Main specifications driving the CMOS design (1/3) Channels l ± Dl (nm) Pitch (µm) 6 Vis ± Vis ± Vis ± Vis ± Vis ± Operability: 4 pixels columns 1 nominal selected by SPI 3 redundant same design as IR detectors Very large rhombus pixel shape up to 100µm to optimize FTM and SNR performance

7 MTF Main specifications driving the CMOS design (2/3) MTF: aliasing effect minimized by adaptation of N/S and E/W of the pixel 0.54 Example for VIS 0.4 fs=1/pitch f/fs=0,42 f/fs=0,54 E/W N/S E/W N/S > 0,54 > 0,4 < 0,34 < 0, f/fs SNR: radiometric performance maximised by the rhombus geometrical extension and noise minimization using CDS at pixel level 7 Vis 0.4 Vis 0.5 Vis 0.6 Vis 0.8 Vis 0.9 Level at E max 2.2 Me 2.1 Me 530 ke 1,2 Me 220 ke Level at E min 15 ke 16.5 ke 4,5 ke 10 ke 2.7 ke Max readout noise <480 e <470 e <120 e <290 e <50 e SNR spec. at E min >22 >25 >23 >24 >22 At least 4T pixel integrating pinned photodiode Readout noise is not a design driver

8 Main specifications driving the CMOS design (3/3) Linearity: Choice of pixel structure 8 Error between E min and E max target <±1.5% High stability over the sensor lifetime target <0.05% Temporal remanence <1/1000 Lag management for large pixel Blooming recovery time: target 1 frame Specific optical requirements: Spectral template involves reduced etalon effect. Straylight performance requires low reflectivity on the die surface.

9 Video Control Unit (VCU) description VCU contains FEE (Front End Electronic) integrating Video amplification Clock drivers Low noise biases Redounded VAE (Video Acquisition Electronic) including 14 bits ADC conversion Generation of the clocks SPI signal Supply voltages Management of the redounded thermal sensor. 9 BBM FEE VIS FEE Lin regs BBM VAE VIS VAE VIS BOARD VAE Lin regs. Preamp. (diff.) DA bias gen DA clocks drivers DA thermal sensor IF 2m Video chain 14 bits DIGITAL BLOCK: FPGA + PROM + OUTPUT BUFFER 16 bits + word clk I2C

10 Outline 10 Detector chain description and main specifications BBM Tests description Preliminary results

11 Test description VISDAdetector FEE electronic 11 BBM performances and interfaces electrically representative, however not optically as no filter assembly has been manufactured in the VisDA Test goal: Consolidate and validate all the VisDA, FEE and VAE functional and electrical interface requirements. Verify the detection chain radiometric performances (noise and linearity). Consolidate the design before the CDR of the detection chain parts.

12 Outline 12 Detector chain description and main specifications BBM Tests description Preliminary results

13 Functional test Performance test Functionnal test VCU connection to OGSE Supply DA 13 VCU Te st DA connection to VCU DA functional Test Thermal sensor Test VAE sampling time determination Test OK VCU noise Power FEE Supply noi se rejection Sampling time Yes Generate clocks and mapping VCU radiometric noise ON/OFF sequence test Manage clocks and mapping Ability to acquire an image DA + VCU power consumption DA video signal analysis Plateau reconstruction Dynamic adjustment Radiometric performance Successful Linearity vs Tint Low noise measurement Noise sensitivity to DA temperature Bias l Integr Gain Respo PRNU Linea Radia SNR O Tint re Reado 1/f no RTS n Noise Resp. Idark

14 Noise in darkness 14 Detector dynamic range is 1,6 V Include Electronic Noise + Detector Noise µv rms for most of the channels VisDA 0.9 higher (410µV rms) due to an additional electrical amplifier at pixel level In line with expectation

15 Dark signal non uniformity 15 Very low dark current not measurable with the VCU configuration close to a flight model (low Ti ) The peak to peak dispersion around ±2mV negligible as represent less than 0.25% of the dynamic range

16 Responsivity dispersion 16 Responsivity dispersion < 3% (below Req=5%)

17 1/f noise measurements - Noise Power Spectral Density DA temperaute = 293K, Channel FDVIS-0.9 NPSD level for each pixel of column 1 Averaged Beta = 2.70e-031 A²/Hz, Selected pixel = 218,Averaged knee frequency = 0.00 Hz Vis09 NPSD in A²/Hz Averaged NPSD Fitted NPSD Frequency (Hz) s continuous acquisition in darkness condition maximum time duration between two offset correction in deep space No 1/f noise for f > 0.09Hz

18 Delta in LSB12 Noise in LSB12 Delta in LSB12 RTS measurements 0.4 Channel FDVIS-0.9 column 1 at 293K: Delta = Acq(n)-Acq(n+1) vs TIME. Pixel index with Delta > 0.23 LSB12 0 removed pixels. Index =[, ] Channel FDVIS-0.9 column 1 at 293K: Noise vs TIME. Pixel index noise > 1.03 LSB12 0 removed pixels. Index =[, ] Acq(n)-Acq(n+1) vs TIME (in s) satisfying both difference and noise criteria: removed pixels. Index = [, ] acquisitions in darkness condition of 1000 frames every 10s compute average and noise level for each pixel VisDA not affected by RTS noise

19 NL in % Linearity measurements 4 NL level for all channel FDVIS-0.4 FDVIS-0.5 FDVIS-0.8 FDVIS-0.9 HRVIS Video output in V For level > 0,2 V: 1% more than ±1.5% target More non-linearity at low flux (e.g. for video output level lower than 0.2V) Compensation method envisaged (high stability expected).

20 Conclusions 20 Detection chain breadboard results very encouraging and have fulfilled most of the objectives. Functional and electrical interface requirements consolidated and validated between the VisDA and the VCU. Preliminary characterized detection chain radiometric performance within the expectations. (e.g. noise, DSNU, PRNU, linearity, 1/f and RTS noise) Measurements in progress to determine the conversion voltage factor (CVF) and the signal to noise ratio (SNR). First measurement campaign demonstrated the good working of the visible detection chain based on CMOS image sensor technology for MTG program.

21 Aknowledgements THALES ALENIA SPACE MTG-FCI Detection and instrument Teams would like to thank EUROPEAN SPACE AGENCY, MTG program, for their support in the MTG detection chain development phase. 21 These representative breadboard test campaign has also been made possible thanks to the excellent work of e2v (Chemsford) for the detector and THALES ALENIA SPACE ESPAÑA (Tres Cantos) for the Video Chain Unit. Espana