SITCOMTN-148

LSST Camera Electro-Optical Test Results#

Abstract

‘This note collects results from the LSST Camera electro-optical testing prior to installation on the TMA. We describe the CCD and Focal Plane optimization and the resulting default settings. Results from eo_pipe are shown for standard runs such as B-protocols, Dense and SuperDense PTCs, gain stability, OpSim runs of Darks, and Darks with variable delays. We also describe features such as e2v Persistence, ITL phosphorescence in coffee stains, remnant charge near Serial register following saturated images, vampire pixels, ITL dips, and others.

Electro-optical setup#

Run 7 Optical modifications#

hello world.

This section describes run 7 optical changes to the CCOB, projector, etc.

  • refresh of setup with items the same as IR2 (CCOB, no narrow-beam)

  • diffuser install

  • projector

Projector spots#

hello world.

This section describes the spots and rectangles tested with the 4k projector

  • Projector background

  • Spots on many amps

  • Spots on one amp

  • Optical setup

FCS development#

hello world.

This section describes FCS operation and intervention.

  • Activity with the FCS

  • Fault at end of september & documentation

  • autochanger known light leak

  • Running FCS in emulator mode (OCS)

Characterization#

Dark current and light leaks#

This section describes dark current and light leaks in Run 7 testing.

One of the first tests we attempted with the camera was measuring dark current and sources of light leaks in the camera body.

Light leak mitigation with shrouding the camera body#

Sources of light leak with the autochanger#

After completing the shroud of the camera, we proceeded with several long dark exposures using different filter and shutter conditions to establish our baseline dark condition for testing.

  • We acquired 900s darks with different shutter conditions and the empty frame filter in place.

  • We acquired 900s darks in different filters with the shutter open

Shutter condition impact on darks#
Filter condition impact on darks#

Final measurements of dark current#

Baseline characterization#

Background#

Initial characterization studies performed on LSSTCam were used two primary acquisition sequences.

  • B protocols: this acquisition sequence consists of the minimal set of camera acquisitions, including

    • Bias images

    • Dark images

    • Flat pairs

    • Stability flats

    • Wavelength flats

    • A persistence dataset

  • PTCs (photon transfer curves): this acquisition sequence consists of a sequence of flat pairs taken at different flux levels. The flat acquisition sequence samples different flux levels at a higher density than the B protocol flat sequence, enabling a more precise estimate of flat pair metrics.

Figure showing the density of sampling between PTCs (blue) and B protocols (red)

All EO camera data is processed through the calibration products and electro-optical pipelines to extract key metrics from the data run. The key camera metrics from Run 7, and their comparison to previous runs are discussed below.

Bias metrics#

CTI#
Bias stability#

Dark metrics#

Dark current#
Bright defects#

Stability flat metrics#

Gain stability#

Flat pair metrics#

Row means variance#
Brighter-fatter correlation#
Brighter fatter a_00 coefficient#
Linearity turnoff#
PTC turnoff#
Maximum observed signal#
PTC Gain#
PTC Noise#
Divisidero Tearing#
Dark defects#

Persistence#

Differences from previous runs#

Guider operation#

hello world.

This section describes guider operation.

  • initial guider operation

  • power cycling the guiders to get to proper mode

  • synchronization

  • guider roi characterization

Tree rings#

hello world.

This section describes tree rings.

  • Tree rings without diffuser

  • Tree rings with diffuser

Camera Optimization#

Sequencer Optimization#

hello world.

This section describes sequencer optimization.

  • No-pocket conclusions

  • Overlap conclusions

  • Serial flush conclusions

Persistence optimization#

hello world.

  • Trying new voltages

  • impact on persistence

  • impact on full-well

  • impact on other parameters

Thermal Optimization#

hello world.

This section describes thermal optimization.

  • Background

  • Idle flush off & it’s stability

  • impact on other parameters

Camera stability#

Defect stability#

hello world.

This section describes defect stability.

  • Bright defects

  • Dark defects with picture frame

Bias stability#

hello world.

This section describes bias stability.

  • Typical bias stability runs

  • dark delay

  • dark with bias delays

Gain stability#

hello world.

This section describes gain stability.

  • No temp variation, fixed flux

  • no temp variation, variation in flux

  • Temp variation, fixed flux

Sensor features#

ITL Dips#

hello world.

This section describes ITL Dips.

Vampire pixels#

First observations#

Vampire pixels were first observed in ComCam observations [need more info to properly give context] - Andy’s study on Oct. 8 - Agnes masking effort

LSSTCam vampire pixel features#

The vampire pixels have distinct features, both on the individual defect level, and across the focal plane

Individual vampire features#

  • General size

  • Radial kernel

  • uniformity

Vampire features across the focal plane#

  • sensor type

  • static or dynamic

  • higher concentrations? Particularly bad sensors?

Current masking conditions#

  • Bright pixels

  • Dark pixels

  • Jim’s task

Analysis of flats#

  • LED effect

  • Intensity effect

Analysis of darks#

  • Previous LED effect

  • Intensity of LED effect

  • dark cadence and exposure times

Current models of vampires#

  • Tony & Craig model

  • Others?

Serial remnants#

hello world.

This section describes incomplete serial flush.

  • Background

  • Mitigation with sequencers

  • discussion of different clears

Phosphorescence#

hello world.

This section describes phosphorescence.

  • phosphorescence background

  • phosphorescence on flat fields

  • phosphorescence on spot projections

Observatory integration#

Shutter activity#

hello world.

This section describe shutter activity

  • Shutter test

  • Shutter profiles

  • shutter failures

OCS Integration#

hello world.

This section describes OCS Integration with LSSTCam.

  • OpSim with darks

  • OpSim with shutter control

OCS Mock calibrations#

hello world.

This section describes mock calibrations taken through OCS.

  • Calibration acquisition

  • DM processing

Chiller activity#

hello world.

This section describes failures with the L1 chiller.

  • History of chiller degradation starting in mid october

  • Catalogue of events over week of Nov. 9

  • solution (eventually…)

Conclusions#

Run 7 final operating parameters#

This section describes the conclusions of run 7 optimization and the operating conditions of the camera. Decisions regarding these parameters were decided based upon the results of the voltage optimization, sequencer optimization, and thermal optimization.

Voltage conditions#

Table 1 Voltage conditions#

Parameter

E2V Quantity

ITL Quantity

pclkHigh

2.0

3.3

pclkLow

-6.0

-6.0

dpclk

8.0

9.3

sclkHigh

3.55

3.9

sclkLow

-5.75

-5.4

rgHigh

5.01

6.1

rgLow

-4.99

-4.0

rd

10.5

11.6

od

22.3

23.4

og

-3.75

-3.4

gd

26.0

26.0

Sequencer conditions#

Table 2 Sequencer conditions#

Detector type

File name

E2V

FP_E2V_2s_l3cp_v30.seq

ITL

FP_ITL_2s_l3cp_v30.seq

  • v30 sequencers are identical to the FP_ITL_2s_l3cp_v29_Noppp.seq and FP_E2V_2s_l3cp_v29_NopSf.seq. All sequencer files can be found in the github repository.

Other camera conditions#

  • Idle flush disabled

Record runs#

This section describes run 7 record runs.

All runs use our camera operating configuration, unless otherwise noted.

Table 3 Record runs#

Run Type

Run ID

Links

Notes

B protocol

E1880

E2233

Identical to E1880. Acquired after CCS subsystem reboot

PTCs

E1886

Red LED dense. Dark interleaving between flat pairs

E1881

Red LED dense. No dark interleaving between flat pairs

E748

nm960 dense

E2237

Red LED dense. Acquired after CCS subsystem reboot.

E2016

Super dense red LED. HV Bias off for R13/Reb2. jGroups meltdown interrupted acquisitions, restarted

Long dark acquisitions

E1117

E1116

E1115

E1114

E1075

Projector acquisitions

E1558

Flat pairs, fine scan in flux from 1-100s in 1s intervals. E2V:v29_NoP, ITL:v29_NoPP

E1553

Flat pairs, coarse scan in flux from 5-120s in 5s interval.E2V:v29_NoP, ITL:v29_NoPP

E1586

One 100s flat exposure, spots moved to selected phosphorescent regions.E2V:v29_NoP, ITL:v29_NoPP

E2181

Flat pairs from 2-60s in 2s intervals. Two 15s darks interleaved after flat acquisition. Rectangle on C10 amplifier.E2V:v29_NoP, ITL:v29_NoPP

E2184

10 30s dark images to capture background pattern

OpSim runs

E1717

Long dark sequence, no filter changes

E2330

Short dark sequence, filter changes in headers through OCS

E1414

30 minutes OpSim run with shutter control, filter change, and realistic survey cadence

E2328

Flats with shutter-controlled exposure

E1657

10 hour OpSim dark run, ~50% of darks were acquired properly

Phosphorescence datasets

E2015

10 flats at 10ke- followed by 10x15s darks

E2014

1 flat at 10ke- followed by 10x15s darks

E2011

20 flats at 10ke- followed by 10x15s darks

E2012

10 flats at 1ke- followed by 10x15 s darks

E2013

10 flats at 10ke- followed by 10x15s darks. Interleaved biases with the darks

Tree ring flats

E1050

E1052

E1053

E1055

E1056

E1021

E1023

E1024

E1025

E1026

Gain stability runs

E1955

E2008

E1968

E1367

E1362

E756

E1496

Persistence datasets

E1503

E1504

E1505

E1506

E2286

E1502

E1501

E1500

E1499

E1498

E1494

E1493

E1492

E1490

E1491

E1489

E1488

E1487

E1486

E1485

E1478

E1477

E1479

E1483

E1484

Guider ROI acquisitions

E1510

E1518

E1519

E1508

E1509

E1520

E1511

E1521

E1512

E1513

E1514

E1517