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a large focal plane of 4k x 4k pixels Tang Qijie Laboratory of - - PowerPoint PPT Presentation

Dec 30, 2023 1.16k likes •1.4k views

PIXEL2018 Design of a scientific CCD camera with a large focal plane of 4k x 4k pixels Tang Qijie Laboratory of Astronomical Technology State Key Laboratory of Technologies of Particle Detection and Electronics School of Physics Sciences,

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SLIDE 1

PIXEL2018

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Design of a scientific CCD camera with a large focal plane of 4k x 4k pixels

Tang Qijie Laboratory of Astronomical Technology State Key Laboratory of Technologies of Particle Detection and Electronics School of Physics Sciences, University of Science and Technology of China

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SLIDE 2

PIXEL2018

  • Astronomical seeing is the best of all the sites on earth.
  • low perceptible water vapor, weak infrared background radiation are conducive to infrared and

sub-millimeter wave astronomical observation.

  • Continuous darkness and the abundant clear-sky nights.

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Kunlun Station at Dome A

Advantages of the Antarctic observatory site

  • The average annual temperature: -25 ℃,

the lowest: -88 ℃.

  • Dry climate, low precipitation
  • Windy, with wind speeds averaging 17m/s
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SLIDE 3

PIXEL2018

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  • CSTAR(Chinese Small Telescope Array)
  • Sites testing

– Cloud cover – Sky background – Seeing

  • Exoplanet surveys

– Ongoing planetary transit survey – Planetary compositions, internal structures and atmospheres beyond our solar system

China's Astronomical Projects in Antarctica

  • BSST(Bright Star Survey Telescope)
  • AST3(Antarctic Survey Telescope)
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SLIDE 4

PIXEL2018

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Telescope CSTAR BSST AST3 Camera model DV435 iKon-XL STA CCD model CCD47-20 CCD303-88 STA1600-FT Number of pixels 1024 x 1024pixels 4096 x 4136pixels 10560 x 10560 pixels Pixel size 13 micron pixel 12 micron pixel 9 micron pixel Type Back Illuminated Back Illuminated Back Illuminated Maximum data rate 1 MHz 3 MHz 1 frame/second Outputs 1 4 16 Readout noise 7.5 e- at 1 MHz; 6.9 e- at 500 kHz 7.5 e- at 1 MHz; 4.2 e- at 100 kHz 7-9 e- at 1 MHz; 5 e- at 100 kHz Charge storage 80,000 e- 350,000 e- 80,000 e- Quantum Efficiency > 90% > 95% > 90% Dark signal 0.06 e-/pixel/second (at -40℃) 0.3 e-/pixel/second (at -25℃) 0.3 e-/pixel/second (at -100℃)

  • CCD Cameras

China's Astronomical Projects in Antarctica

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SLIDE 5

PIXEL2018

  • Problems with commercial CCD cameras

– Extremely low temperature operation environment – Not adequately tested at extremely low temperatures – Expensive

  • Requirements of larger telescope in future
  • Self-designed, customized

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Parameter Specification Telescope aperture 300 mm Field of view 3.4° CCD pixel 12 um Image scale 3” per pixel Image quality 1.5-3 pixel FWHM over entire field Maximum speed 2°s-1 Pointing accuracy <3’ Tracking accuracy 1.5” in 5 min (RMS) Operation temperature

  • 80℃ ~ 40℃

Technical Specifications of the BSST

BSST(Bright Star Survey Telescope)

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SLIDE 6

PIXEL2018

  • Refrigeration: Thermoelectric Cooler (TEC)

– Operation temperature: -80 to 40 ℃ – Air cooling: 50 ℃ below room temperature – Water cooling: 70 ℃ below room temperature

  • Vacuum: Vacuum maintainability
  • Readout: two readout modes

– ACDS mode: 100KHz and 500KHz data rate, noise < 10 e- – DCDS mode: 3MHz max data rate, noise < 10 e- at 1MHz – High gain or high dynamic range mode are optional – Dark signal: 0.08 e-/pixel/second (at -40℃)

  • Dimension:

– Image size: 61.4 mm x 61.4 mm

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∅165×275mm

Main technical parameters

Number of pixels 4096(H) x 4112(V) Pixel size 15 μm square Image area 61.4 mm x 61.4 mm Outputs 4 Package size 63.80 mm x 79.60 mm Package format aluminium oxide PGA Flatness <20 μm (peak to valley) Amplifier sensitivity 2.5 μV/e- Readout noise 8 e- at 1 MHz; 4 e- at 50 kHz Maximum data rate 5 MHz Charge storage 150,000 e- Dark signal 0.2 e-/pixel/second (at -25℃) Spectral range 300-1060nm Type Back Illuminated, Full-frame

CCD230-84 Scientific CCD Sensor

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SLIDE 7

PIXEL2018

  • Vacuum acquisition and long-term maintenance
  • Low noise electronics
  • Complex readout and control circuit of large

focal plane CCD

7 CCD Controller

Clocks and Biases Driver

Vacuum Chamber

TEC and Temperature Sensor

CCD 230-84

Video Readout (4 channels ACDS/DCDS) Temperature Sampling Main Control (FPGA)

Power System

USB 3.0 Interface

CCD Driving Video signals

Optical Fiber

MONITOR MONITOR

Temperature controller Power Second-stage LDO and filter

A+33V, A±5V, D+12V, D+5V

Microcontroller Unit (STM32)

RS232 DC24V IN

Hardware Structure

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SLIDE 8

PIXEL2018

Low Temperature Vacuum Chamber

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  • Key points and Difficulties

– Vacuum acquisition and vacuum maintenance – Refrigeration effect – Miniaturization – Low temperature resistance

Methods Advantages Disadvantages Liquid Nitrogen Low refrigeration temperature Liquid nitrogen difficult to supply; The Dewar is large Cryocooler Low refrigeration temperature; maintenance free Vibration; High cost TEC Flexible; Vibrationless; Low cost Limited refrigerating capacity Air cooling Water cooling Room temperature 31℃ 31℃ Cold side temperature

  • 26.8℃
  • 44.7℃

Hot side temperature 43.0℃ 20.6℃ Temperature difference between cold side and room temperature 57.8℃ 75.7℃ Temperature difference between cold and hot sides 69.8℃ 65.3℃

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SLIDE 9

PIXEL2018

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Multichannel Power Supply with Voltage Monitor TEC Drive with Current Monitor STM32

Voltage Set and Sample TEC Control

19 Pins Socket

Analog and Digital Power RS232 TEC Power

DC24V IN 2m Cable CCD Controller

CCD Power System

  • Multichannel Ultralow Noise Power Supply
  • TEC Controller

CCD Power Box

DC24V IN DC/DC LM25576 Filter (Capacitors and BNX) Filter (Capacitors and BNX) Low Noise LDO TPS7A4701

+18V

DC/DC LM25576 Filter (Capacitors and BNX) Low Noise LDO TPS7A4701

+18V

DC/DC TPS55340 Filter (Capacitors and BNX) Low Noise LDO TPS7A4701

+34V A+17V_2

DC/DC LM25576 Filter (Capacitors and BNX) Low Noise LDO TPS7A4701

+6.5V A+17V_1 A+33V A+6V

DC/DC LM25576 Filter (Capacitors and BNX) Low Noise LDO TPS7A33

  • 6.5V

A-6V

DC/DC LM25576 Filter (Capacitors and BNX) DC/DC LM25576 Filter (Capacitors and BNX)

+12V +6V D+12V D+6V A+6.5V for DCDS ADC

CCD Power System

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SLIDE 10

PIXEL2018

Multichannel Power Supply - Performance Tests

Voltage RMS Noise Max Current Analog +33V 31.0uV 1A Analog +17V 64.8uV 1A Analog +17V 64.8uV 1A Analog +6V 40.7uV 1A Analog -6V 40.7uV 1A

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Background noise of oscilloscope Total noise of power output Spectrum of +33V output Noise vs Temperature +33V Output Voltage vs Temperature

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SLIDE 11

PIXEL2018

TEC Controller

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  • Voltage controlled voltage source
  • High driving capability: 20V, 10A Max
  • Low output ripple
  • Digital PID control algorithm

STM32

DAC Set Voltage

TEC Temperature Sensor PT100

Heat Conduction

ADS1248 Sampling by FPGA DC/DC TPS40056

Temperature Data Current Drive

Power Supply Box Camera

  • 50
  • 40
  • 30
  • 20
  • 10

10 20 30 40 50 500 1000 1500 2000 2500 3000

Temperature/℃ Time/s

TEC refrigeration curve

CT HT

  • Temperature Sensor: 4-wire PT100
  • High Temperature measurement accuracy: 0.002℃
  • Temperature stability < 0.01℃
  • Temperature stabilization time < 30 minutes
  • Cooling rate < 5 ℃/minute
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SLIDE 12

PIXEL2018

CCD Controller - Driving solution

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  • Clock: 40 Channels
  • Bias: 6 kinds of amplitude
  • Amplitude setting:

– AD5391, 16-channel, 12-bit

  • Voltage Monitor:

– AD7928, 8-channel 12-bit

  • Clock Power Supply:

– OPA + BJT

  • Clock Drive:

– EL7457, 40MHz Quad CMOS Driver

  • Bias Power Supply:

– OPA ADA4075, 2.8 nV/√Hz

Preamplifier Board EF Channel Preamplifier Board GH Channel Pinboard Pinboard Clock Driver EL7457 4 Channels x10 Bias Switch MAX313 4 Channels x2 Dual OPA x3 BJT and Dual OPA x5

DIP DIP

DAC and Filters

Clock Amplitude Setting Bias Amplitude Setting 40 Channels Clocks 6 Channels Bias

Clock and Bias Board

Voltage Monitor AD7928 x2

Bias Control

FPGA1

Clock Source

DAC

BIAS_CCD A

DAC

VCLK_H VCLK_L

EL7457

VH VL

IN1 IN4 OUT1 OUT4

CLK_FPGA CLK_CCD A A

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SLIDE 13

PIXEL2018

CCD Controller - Driving solution

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– Clock edge adjustment – Reduce crosstalk by optimizing clock timing

Clock waveform without processing Clock waveform with processing Line Transfer Clock Readout Clock

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SLIDE 14

PIXEL2018

CCD Controller - Readout solution (ACDS)

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  • ACDS: Analog Correlated Double Sampling
  • Dual Slope Integration

CCD Preamplifier Second-stage Amplifier Invert/Non-invert Select Integrator ADC FPGA

Integrate/Reset Invert/Non-invert

CDS G1 G2 G3

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SLIDE 15

PIXEL2018

CCD Controller - Readout solution (DCDS)

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  • DCDS: Digital Correlated Double Sampling

CCD Conditioning DCDS

Video Data

Analogue Digital

Oversampling ADC

  • DC restore
  • Anti-alias filter
  • Digital low pass filter
  • correlated double sampling
  • Precise adjustment of sampling point position
  • 105Msps, sampling 16-Bit A/D converters

ADC Output Reference samples Signal samples

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SLIDE 16

PIXEL2018

Gain measurement

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y = 2.1521x - 422.09 R² = 0.9999 5000 10000 15000 20000 25000 2000 4000 6000 8000 10000 Signal/ADU Variance/ADU

Photon Transfer Curve (ACDS)

y = 1.8428x - 673.42 R² = 0.9999 10000 20000 30000 40000 50000 5000 10000 15000 20000 25000 Signal/ADU Variance/ADU

Photon Transfer Curve (DCDS)

  • The gain of ACDS mode is inversely proportional to the

integration time.

  • The gain of DCDS mode is independent of the number of

signal samples.

Mode Readout Speed Integration Time Gain ACDS 100kHz 2000ns 1.2176 e-/ADU ACDS 500kHz 680ns 2.1521 e-/ADU DCDS 500kHz 35points/467ns 1.8428 e-/ADU

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SLIDE 17

PIXEL2018

Noise Performance

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Temperature 100kHz; 3500ns 100kHz; 2000ns 500kHz; 680ns 25℃ 8.78 e- 10.79 e- 9.15 e-

  • 25℃

6.73 e- 7.79 e- 8.59 e-

  • 40℃

6.75 e- 7.69 e- 9.06 e- Temperature 500kHz; 46 points 500kHz; 35 points 1000kHz; 21 points 25℃ 9.32 e- 10.49 e- 14.28 e-

  • DCDS
  • ACDS
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SLIDE 18

PIXEL2018

Imaging Tests

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SLIDE 19

PIXEL2018

Conclusions

  • Completed the development of the 4k x 4k pixels CCD camera
  • Vacuum maintenance, miniaturization, cooling capacity and low

temperature resistant

75℃ below room temperature

  • Low noise clock and bias driver
  • low noise high precision readout system, ACDS and DCDS
  • The readout noise reaches the advanced level

< 10 e- at 500KHz

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SLIDE 20

PIXEL2018

Future outlook

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  • KDUST: Kunlun Dark Universe Survey

Telescope

– Aperture: 2.5m – 25 pieces of 8K x 8K CCD spliced

  • WFST: Wide Field Survey Telescope

– Aperture: 2.5m – 9 pieces of 9K x 9K CCD spliced

  • Mephisto: Multi-channel

Photometric Survey Telescope

– Aperture: 1.6m – 4 pieces of 9K x 9K CCD spliced

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SLIDE 21

PIXEL2018

Future outlook

  • Higher requirements for the development of the large focal plane splicing

CCD detector system

  • Modularization , ASIC
  • The reduction of readout noise of CCD detector system

Thanks for your attention!

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