Michela Uslenghi INAF/IASF Milano WSO/UV Italian web site: Detectors for.

Michela UslenghiINAF/IASF MilanoWSO/UV Italian web site:

http://www.oact.inaf.it/wso/index.htm/

Detectors for the FCU

WSO/UV World Space Observatory / Ultraviolet Project



http://www.mi.iasf.cnr.it/index.php

Leicester, December 3-5 2007 WSO Detector Workshop

Outline

• Overview of the Field Camera Unit• UVO Detector

– CCD– FEE

• NUV & FUV Detectors– Requirements– Selection process– Baseline architecture– MCP intensifier– Readout system– FEE

• R&D



Imager requirements• Large wavelength coverage (115-700 nm)• Large field of view• High spatial resolution

– Morphological studies (e.g. planets, planetary nebulae, star formation regions, external galaxies)

– High accuracy stellar photometry– High accuracy stellar astrometry– Resolve stars in crowded fields (e.g. in star

clusters, external galaxies, star formation in AGNs)

• High time resolution in the UV



Science requirements for the FCU camera

Parameter Channel

Far-UV Near-UV UV-Optical

Spectral Range 115-190 nm 150-280 nm 200-700 nm

Field of View 6.6’x6.6’ 1’x1’ 4.7’x4.7’

Scale 0.2”/pix 0.06”/pix 0.07”/pix

Pixel Size 20m 20m 15m

Array Size 2kx2k 2kx2k 4kx4k

Detector MCP (CsI) MCP (CsTe) CCD (UV optimized)



FCU Layout

NUV Channel FUV Channel

UVO Channel



Enclosure

FUV Filter Wheel

Detector

FUV ChannelNUV Channel

Detector

NUV Filter Wheel

Baffle

Enclosure

Mechanical DesignUVO Channel

Detector

UVO Filter Wheel Baffles

Enclosure

Fore Optics

FCU Optical BenchS/C Optical Bench



Operational Modes

– Imaging (FUV, NUV, UVO)– Slitless spectroscopy (FUV, NUV,

UVO)– Polarimetry (NUV, UVO)– Slitless spectro-polarimetry (NUV)

• High Temporal Resolution Modes

– Time Tag (MCP)– Windowing (CCD, MCP)



UVO Detector

• The UVO channel will extend from UV to visual wavelengths

• The pixel scale of this channel is a compromise between the need of a large field of view and high spatial resolution.

• Filters, dispersers and polarizers narrow and broad band imaging, low resolution (R ~ 100-500) slitless spectroscopy and imaging polarimetry.

• Single CCD detector optimized for the UV wavelength range.



UVO CCD

• CCD device back illuminated with AR coating optimized in the UV range.

• 4k 4k pixels • Pixel size will 15 m square • Exposures will be split in sub exposures

with integration times ≤ 15-20 minutes (due to cosmic ray contamination) requirement on the dark current rate of 20 e–/pix/hr.



E2V CCD231-84

UVO channel CCD detector preliminary functional requirements

Quantity Required Goal

Pixel size 15 x 15 microns

15 x 15 microns

Array Size 4096 x 4096 pixels

4096 x 4096 pixels

Package size 70 mm x 70mm

65mm x 65mm

Surface Flatness (peak to valley) 20 20

Dark current rate, e–/pixel/hour 20 15

Readout Noise @ 200 kHz (e– rms) 4.0 3.0

Linearity over 70% of full well capacity 1.0% 0.1%

Full Well Capacity (image area), electronsFull Well Capacity (register area), electrons

275000850000

350000850000

Wavelength Range 200 – 700 nm 200 – 900 nm

DQE Stability over 1 month (peak to peak) 5.0% 1.0%

Charge Transfer Efficiency (Parallel & Serial)

0.999990 0.999995

Flat Field Non-uniformity Limit (1) 5.0% 3.0%

Flat Field Stability Limit, peak-to-peak over one month

1.0% 0.5%

Black & White Spots (pixels) 800 400

Maximum number of Column Defects 5 0

Traps 10 5

Operating Temperature, C –952 –952

QE: -100°C e2v Typical QE Astronomy Process with UV coating

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

200 300 400 500 600 700 800 900 1000

Wavelength (nm)

QE



UVO detector package assembly

(preliminary design)Main components will be: a baseplate.• a mounting support for the CCD• the CCD detector• a cover • a flat quartz window and optical baffles. The baseplate will have holes for connectors and will host getter pumps to provide long term pumping against residual outgassing products. There will be no FEE inside the package assembly. The FEE will be accommodated on the backside of the baseplate. Hermetic feedthroughs connectors will ensure electrical continuity between the CCD and the FEE PCB/ASIC.



CCD Readout

Full Frame Readout Time (sec)

Outputs 100 kHz 200 kHz

500kHz

1 168 84 32

2 84 42 16

4 42 21 8

Operative modes:

• Windowing: selection of a set of fixed sub-array apertures and user-defined sub-arrays

• Binning: 2x2, 3x3, 4x4

• Gain: to fully exploit the CCD well capacity the controller must allow the selection of different gains



UVO CCD electronics system

Timing Board: Commands CCD exposures. Generates TTL level clocks for the CCD timing pattern. Generates biases digital data.

• Clock Driver: translate the TTL level clocks to CCD clock voltages and send them to the CCD.

• Bias Generator / Analog Signal Processing: translate the biases digital data generating the bias voltages to operate the CCD. Digitize the signal from the CCD outputs to 16-bit accuracy.

Low Noise Preamps: receive the signal from each of the CCD outputs and send it to the analog signal processing board.



Requirements for NUV&FUV detectors

Parameter FUV NUV

Array size 2048x2048 2048x2048

Active area 40 mm 40 mm

Pixel size 20 µm 20 µm

Spectral range 115-190 nm 150-280 nm

QE > 20%@130 nm<1.e-5%@≥400nm

> 10%@180 nm<0.1%@≥400nm

Time resolution ≤20 ms ≤20 ms

LDR ≥20 counts/s ≥20 counts/s

GDR ≥2*105 counts/s ≥2*105 counts/s



Some considerations on detector choice

• Directions from the science team: the more important characteristic is the spatial resolution (in particular for the NUV)

• Very short WSO schedule: no R&D• Looking for something available now.

Delivery time should fit the schedule• Avoid (if possible) ITAR



Baseline configuration of the UV detectors

• PC-ICCD

– Photocathode– 2-3 stages MCP

intensifier– Phosphor

screen– Fiber Optic

taper– High speed CCD

camera– Real time digital

electronics unit



FUV & NUV Detectors

FUV & NUV Channel: MCP-based detector in sealed configuration

Format: 2kx2k (40mm)

Read-out system: CCD

Photocathodes: CsI (FUV), Cs2Te (NUV)



Photek 40 mm



MCP intensifier

• MCP 2-stages (Chevron)• Diameter 40 mm• Pore size 10 m (12 m)• L/D I 50:1

II 80:1• Gain 5•105 e-• Pulse Height Distribution (PHD) <125% FWHM

• PHD spatial variation <10% peak-to-peak• Dark Counts @ 20C <1 counts/cm2s• Photocathode CsTe/CsI • Window MgF2

• Phosphor screen P46• Sealed configuration



Photocathodes



CsI Photocathode

DQE for the CsI coated ACS SBC MCP

0,01,02,03,04,05,06,07,08,09,010,0

120 140 160 180 200 220

W/length nm

QE

%Photek data

Semitrasparent vs opaque photocathode



CCD Readout sensor

Sarnoff VCCD-512• Format 512 x 512 pixels• Pixel size 18 x 18 m2

• Architecture Splitted FT• Full well 240,000 e-

• Fill factor 100%• N. of output Ampl. 16• Readout frequency 10 MHz (per

amplifier)• Frame rate 500 frames/s

Require:

• 4x centroid subpixel resolution



PC-ICCD Electronics Overview

ICU

The detector electronics include two main blocks:

an Analog Front-End Electronics (AFEE), an high speed front-end CCD electronics a Digital Front-End Electronics (DFEE) with a real time data processing unit, which will acquire the data from the CCD camera, search for the photon events and computes the coordinates of the detected photons with sub-pixel accuracy

Filters for the High Voltage Power Supply should also be located close to the detectors.



DFEE: data processing and centroiding

The DFEE will acquire serially the CCD digitized output signals + sync signals (frame, line and pixel sync), reorder them (if required), and subdivide the frame in sub-regions to be analyzed by parallel processors, each one implementing the following tasks:

– through a proper system of delays, the processor will generate 33 pixel windows that sweep dynamically the whole matrix to be analyzed at the pace of the pixel clock;

– on each window: • check, according to appropriate discrimination and pile-up

rejection criteria, for the presence of a charge distribution representing a photon event;

• compute the centroid coordinates with a centre of gravity algorithm to the charge distribution in the current window and correcting for systematic errors.

All the operations should be done in real time no limits should be introduced by the electronics on the dynamic range

implementation in FPGA, adopting a pipeline architecture in order to process the data at the rate they are generated by the sensor



System Overview



Local Dynamic Range

0 100 200 300 400 5000

50

100

150

200

250

300

350

400

450

500

Linear responsesingle/double as singlesingle/doublesingle

Dynamic response

counts/s in

coun

ts/s

out

1 10 100 1 1030.3

0.4

0.5

0.6

0.7

0.8

0.9

1

single/double as singlesingle/doublesingle

DQE vs count rate

counts/sD

QE



LDR translated to magnitudes …

Magnitudes giving SNR 10 on 3600 s (only source counts statistics is considered) O3V O5V O6V O8V B0V B3V B5V B8V A0V A5V F0V F5V G0V G5V K0V K5V M5V FUV F122M 25.8 25.7 25.6 25.3 25.3 24.1 23.1 22.0 19.8 16.4 14.2 11.6 9.1 7.9 6.2 5.3 5.3 FUV F130LP 28.1 28.0 27.8 27.6 27.6 26.6 26.0 25.3 23.9 21.4 19.8 17.8 15.5 14.4 12.3 6.9 6.4 FUV F157W 26.4 26.3 26.2 26.0 26.0 24.8 24.1 23.3 21.7 18.8 16.6 13.8 11.2 10.0 7.8 5.5 5.5 FUV F160BW 26.4 26.4 26.2 26.0 26.0 24.8 24.1 23.1 21.5 18.9 16.8 14.1 11.5 10.3 8.2 5.6 5.5 FUV F165LP 26.3 26.2 26.1 26.0 26.0 24.9 24.2 23.5 22.4 21.3 19.7 17.1 14.6 13.5 11.3 6.2 6.0 FUV F170W 26.6 26.6 26.4 26.3 26.3 25.1 24.5 23.6 22.3 20.4 18.5 15.9 13.3 12.1 9.9 5.8 5.7 FUV Clear 28.9 28.8 28.7 28.5 28.5 27.3 26.5 25.6 24.0 21.8 19.9 17.4 14.8 13.7 11.5 6.3 6.1 NUV F170W 26.1 26.0 25.9 25.8 25.8 24.7 24.1 23.3 22.2 21.2 19.9 18.2 16.6 15.8 14.0 10.5 10.2 NUV F218W 25.7 25.7 25.6 25.5 25.5 24.5 24.0 23.3 22.3 21.8 21.0 19.9 18.8 18.0 16.0 11.6 11.2 NUV F255W 25.0 25.0 24.9 24.8 24.8 24.0 23.5 22.8 21.9 21.5 20.9 20.2 19.5 19.0 17.9 14.0 13.4 NUV Clear 28.7 28.7 28.6 28.4 28.4 27.4 26.8 26.1 25.1 24.5 23.8 23.0 22.2 21.7 20.6 16.8 16.1

Low limit:

High limit:

Range: 8.9 magnitudes

Magnitudes giving 100 counts/s (PC-ICCD with 500 frames/s sensor) O3V O5V O6V O8V B0V B3V B5V B8V A0V A5V F0V F5V G0V G5V K0V K5V M5V FUV F122M 16.9 16.8 16.7 16.5 16.5 15.2 14.3 13.1 10.9 7.5 5.3 2.7 0.2 -0.9 -2.7 -3.5 -3.5 FUV F130LP 19.2 19.1 18.9 18.7 18.7 17.7 17.1 16.4 15.0 12.5 10.9 8.9 6.6 5.5 3.4 -2.0 -2.5 FUV F157W 17.5 17.4 17.3 17.1 17.1 15.9 15.2 14.4 12.8 9.9 7.7 4.9 2.3 1.1 -1.1 -3.4 -3.4 FUV F160BW 17.5 17.5 17.3 17.1 17.1 15.9 15.2 14.3 12.6 10.0 7.9 5.2 2.6 1.5 -0.7 -3.3 -3.4 FUV F165LP 17.4 17.3 17.2 17.1 17.1 16.0 15.4 14.6 13.5 12.4 10.8 8.3 5.7 4.6 2.4 -2.7 -2.8 FUV F170W 17.8 17.7 17.5 17.4 17.4 16.2 15.6 14.8 13.4 11.5 9.6 7.0 4.4 3.2 1.1 -3.1 -3.2 FUV Clear 20.0 19.9 19.8 19.6 19.6 18.4 17.6 16.7 15.1 12.9 11.0 8.5 5.9 4.8 2.6 -2.5 -2.8 NUV F170W 17.2 17.1 17.0 16.9 16.9 15.8 15.2 14.4 13.3 12.3 11.0 9.3 7.7 6.9 5.1 1.6 1.3 NUV F218W 16.8 16.8 16.7 16.6 16.6 15.6 15.1 14.4 13.5 12.9 12.1 11.0 9.9 9.1 7.1 2.7 2.3 NUV F255W 16.1 16.1 16.0 15.9 15.9 15.1 14.6 13.9 13.0 12.6 12.0 11.3 10.6 10.2 9.0 5.1 4.5 NUV Clear 19.8 19.8 19.7 19.6 19.6 18.5 18.0 17.2 16.2 15.6 14.9 14.1 13.3 12.8 11.7 7.9 7.2

V Johnson



UV detectors data flux

The DFEE produces a 32-bit word for each detected photon, with the x,y,t coordinates (plus “amplitude”, used for monitoring). These words are sent, via Spacewire interface to the ICU. Operative mode (science + calibration) are (software) implemented in the ICU At least two operative modes (+windowing) will be implemented for science observations:

1) time tag mode: photon list {x,y,t} is sent to the SDCU and then to ground. Data rate depends on the flux of incoming photons (which in turn depends on filters and sources in the field)

2) accumulation mode: before sending them to the SDCU, counts are accumulated by the ICU in an array in which each element correspond to a pixel, eventually producing a CCD-like image limit data rate by loosing time information, allowing exposures with high count rate.

MCP Detector

A/D FEE

DigitalFEE

ICU

P

Spacewire(> 80 Mbps)

{x,y,t,A}

SDCU

MIL-1553B

Mode 1: {x,y,t}

Mode 2: 2Kx2K image

MCP Detector

A/D FEE

DigitalFEE

ICU

P

Spacewire(> 80 Mbps)

{x,y,t,A}

SDCU

MIL-1553B

Mode 1: {x,y,t}

Mode 2: 2Kx2K image

SDMU



Model Philosophy (Moscow)• WSO-UV plans

– Full Scale Model – MSM (May 2008)

• Mass Model + Structural Model

– Thermal Equivalent – TM (Jan 2009)

– Technological Model – EM (Jan 2009)

– Instrumentation Flight Set Model – FM (May 2009)

Our proposal:• Bread Boards (not deliverable)• Structural Thermal Model

(deliverable, should be returned)– Optical Bench– Mass dummies– Thermal dummies

• Engineering Model (deliverable)– Mock-up optics and detectors– Functional representative of

the flight model at Bus functional I/F level

– Optical Bench: Initially could be a plate to be replaced by OB when performing EMC tests or bus mechanical/functional integration tests.

• Flight Model (deliverable)


Previous R&D on photon counting detectors



PC-ICCD for for ground-based ground-based

astronomyastronomy

Photocathode

MCP in

MCP out

P20Phosphor Screen

F.O.Output Faceplate

F.O. Taper

CCD Array

-2300 Volt-2100 Volt

-1400 Volt

Ground

+5.5 KVolt

HV

Window: quartz

Photocathode: S20

MCPin

MCP out

Phosphor Screen:P46

Fiber OpticFaceplate

Fiber Optic Taper: 2.4:1

CCD

EEV CCD17

Data Acquisition

NI PCI-DIO32HS

GPS

DATUM BC635PCI

FIFO Data

Buffer

Data OUT

PC Host

Camera Control

Data Acquisition

NI PCI-DIO32HS

GPS

DATUM BC635PCI

FIFO Data

Buffer

Data OUT

PC Host

Camera Control



PC-ICCD characteristicsArray Size 2048 2048 pixel (1)

2048 512 pixel (2)

Pixel Size 13.5 13.5 m2

Spatial Resolution 25 m (FWHM) @ 550 nm 30 m (FWHM) @ 254 nm

Time Resolution 16.8 ms (1)4.512 ms (2)

Detective Quantum Efficiency (DQE)

8.2% @ 229 nm6.8% @ 254 nm

Visible Light DQE 0.074% @ 405 nm

Spectral Range (DQE 1%)

120-300 nm

Dark Count Rate 1.74 cts s-1cm-2

Local Dynamic Range (DQE loss < 10 %)

13 cts s-1 (1)54 cts s-1 (2)

Global Dynamic Range (DQE loss < 10 %)

2.6 104 cts cm-2 s-1 (1)9.2 104 cts cm-2 s-1 (2)



Spatial Resolution

Readout system:

FWHMx~ 5 m

Front MCP pore structure fully resolved

Detector:

FWHMx~ 25 m @ 5500Å

limited by proximity focus



Dynamic Range

10% fractional count rate loss:

Local:

• 13 cts/s @ full frame

• 54 cts/s @ window

Global:

• 2.6·104cts cm-2 s-1

• 9.2·104cts cm-2 s-1



Asiago-Cima Ekar

• 182 cm Telescope + AFOSC (3 filter wheels allowing combination of: photometric filters, grisms, Echelle grisms, polarimeter based on a double Wollaston prism)

High speed Photometry & spectroscopy of CV & Flare stars



Crab Pulsar

•PFFT=0.0334881±1.5·10-7 s

•PEF=0.033488256±8·10-9 s



1WGA 1958.2+3232

S1

0 5 10 15m Hz

05

10

15

20

2530Periodogram

10%0.1%

S3

0 5 10 15m Hz

0

10

20

30Periodogram

10%

S7

0 5 10 15m Hz

0

10

20

30Periodogram

10%



PC-IAPSObjective Holder

Electronic Board

CMOS - APS

Light Tight

MCP

Lens Objective

HVConnector

1024x1024 pixel1024 8-bit ADC on chip (one for each column)8 parallel outputsUp to 500 frame/s full frame (+windowing)



PC-IAPS FEE Board

The APS is mounted on a 10 cm x 10 cm PCB board, which also hosts the driving electronics, the real time data processing unit and the interfaces to the host PC. The core of the electronics is a single FPGA, XILINX XCV 800 (800 Kgates equivalent), allowing a very compact design.



PC-IAPS FEE Overview• At each clock pulse, the 64 bits data output (8 pixels x 8-bit) are acquired by the data processor. • Synchronous FIFO are used as delay line that allows a concurrent sampling of a pixel together with its nearest neighbors. • Upon initialization, a set of D-Latches is used to map 8 windows of 3x3 pixels, which covers dynamically the whole APS image at the pace of the pixel clock. This allows the whole APS frame to be analyzed, avoiding problems of either fixed or dynamic image partitioning. • The processing system performs in parallel the following tasks on each window:

Check (discrimination and pile-up rejection criteria) for the presence of a photon event; compute the centroid coordinates and transfer them to a PC.


Michela Uslenghi INAF/IASF Milano WSO/UV Italian web site: Detectors for.

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