FPA (Focal Plane Array) Characterization set up (CamIRa ... · For performing experimental and characterization studies on 320x256 QDIP Focal Plane Array and Indigo 9705 ROIC, a CamIRa

05 July 2013 CamIRa Test Setup Description and Operation Document Page 1

FPA (Focal Plane Array)

Characterization set up (CamIRa)

Standard Operating Procedure

FACULTY IN-CHARGE Prof. Subhananda Chakrabarti (IITB)

SYSTEM OWNER Hemant Ghadi ([email protected])


Contents

SL No. Topics Page No.

1. Introduction – Description - Overview 1

2. CamIRa Test Setup 6

3. Preparing to Run a Standard Test 10

4. The Standard Test Process 13

5. Terminologies and Algorithms 26

6. Data Files 40


1. Introduction – Description - Overview

What is QuickTest ?

QuickTest works with SE-IR test equipment to automate the FPA characterization process. It combines

programmed changes to the FPA operating conditions, data acquisitions, data storage, data reduction to yield

standard FPA figures of merit in an Excel-based report, analysis tools to determine readout gain and excess

current.

Test time for a typical FPA is 60 minutes excluding cool-down. Because the user does not need to write

any software, the user can characterize an FPA and provide a report after the SE-IR hardware is set up.

QuickTest also provides a radiometric calculator, and a routine to display acquired data in a view-graph

format, and a Field of View tool.

Quick Test includes all necessary algorithms for normal IR FPA testing: standard figures of merit,

radiometric calculations (Plank’s Law, including FOV or “cosine-to-the-fourth” corrections), and statistics:

means, sigmas, medians for all pixels and after masking defective pixels.

The QuickTest software provides …

a quick way to get detailed FPA reports from the SE-IR test hardware

a reliable baseline test for use in auditing other test methods.

a template and “starter kit” to assist in developing custom procedures.

Benefits

QuickIRtest completely eliminates the software coding task, with its problems of resource allocation and

cost and schedule risks.

The procedures are straight-forward and well documented. All algorithms are described clearly.

The standard test provides a respected, reliable testing methodology.

Data acquisition plan is easily visualized – see attached sample.

Data are stored in logical directory structure – easily accessible for future use.

Images and graphs on the reports allow easy assessment of FPA quality.

Tabulated values (min, mean, median, max, sigma) are calculated and reported for all raw data and for derived

data (figures of merit.) Statistical values are reported for all pixels, and also after excluding defective pixels,

and also after excluding "three-sigma" outliers.


Standard Acquisition

The Standard Test acquires 12 files:

Noise - 3 files: Noise1, Noise2, Noise3

DC output w/ zilch integration time

DC output w/ max integration time

DC output – 5 files (2 at TBB-Low, 1 at TBB-Mid, 2 at TBB-Hi)

DC output w/ longer integration time

DC output w/ higher detector bias

During the acquisition process

During the acquisition part of the test, the operator views several intermediate screens or forms that allow him

to control or adjust the test. Default values are set that need not be changed if the array is well-behaved. If the

array is very non-uniform or does not behave as expected, the operator can change conditions to optimize

performance for selected pixels or regions. These forms are automatically saved for examination after the test

is complete

“Setup for DC” allows the operator to adjust integration time, bias, gain, and offset to ensure that outputs are

neither railed nor saturated.

“Bias sweep” – provides graphs of detector current, noise, and uniformity vs bias. This allows the operator to

make an informed choice of the bias to be used for the test -- the best combination of noise and uniformity. The

form also has a drag-able cursor that allows the operator to determine the average RA product for any bias of

interest.

“Linearity Form” – during the acquisition of DC output for three different irradiances, we can also acquire

data at many different integration times. The data are then plotted in three different ways, allowing us to

estimate the ROIC gain (for example, 150 nV/electron), the excess irradiance, the linearity, and the average

QEFF.

“Setup for Noise” – allows the operator to adjust the offset and gain to be used for the noise acquisitions.

“Preview of the Report” – here the operator sees the defect criteria, the number of defective pixels for each of

the defect criteria, the number of clusters of each size, a map of the defective criteria, and the array means after

excluding defective pixels. The operator can change the criteria and see the results, all before printing the

report. Only when the operator is satisfied that appropriate criteria have been selected do we generate the

report.


The Test Report

An Excel based test report is generated automatically at the end of the test. Results include array means and

standard deviations (“sigmas”) for each of the raw data files, number of defective pixels for each of six criteria,

number and location of clusters, and images of the raw and derived parameters. These are automatically

transferred to an Excel template. The test engineer can customize the template prior to the test, or the report can

modified after the test – key results can be highlighted and other calculations can be added using the standard

Excel methods.

Six Criteria for Defective Pixels can be specified by the operator, and the resulting number of defective pixels

and clusters of defective pixels will be reported.

High Noise

Low QEFF

High QEFF

High Spatial Non-Uniformity (after cos4 correction)

High Residual Non-Uniformity (After 2-Point NUC)

Shifters (sometimes called Flashing, Flickering, or Unstable pixels)

Derived data are saved for future analysis

Eight derived data files are saved, showing results for every pixel:

QE-FF

Responsivity

Spatial Non-Uniformity (DC_Mid after cos4 correction)

Corrected Non-Uniformity (DC_Mid after Two-point NUC)

NEI

RrA

Excess Current Ratio

Defect Map (shows which pixels failed which requirements).

Other features

Test Log: Key results of every test are saved to an Excel Test Log – one line per test. This allows convenient

review and comparison of recent tests. (When did we test s/n 123 last? How many times have we tested it?

How many FPAs did we test last week?)

Viewgraph of any file: One form provides a single printable sheet showing a false color image, plots in x and y,

histogram, array statistics, s/n, test date, title, and comments. The user can select the file to be presented as well

as the scales, the title and comments.

The Radiometric calculator displays spectral exitance as a function of wavelength, the "in-band" integrated

exitance, for two different blackbody temperatures, and the corresponding irradiances for any specified cold-

shield geometry.


2. CamIRa Test Setup

For performing experimental and characterization studies on 320x256 QDIP Focal Plane Array and Indigo

9705 ROIC, a CamIRa test setup is used that contains following equipments:

A. Hardware Components:

1. Area Array Sample + ROIC

2. DEWAR Unit

3. MIKRON Blackbody Source (M315)

4. MIKRON -M315 Blackbody Temperature Controller

5. PC with CamIRa software configured for 9705 (1 channel mode)

6. Clock, Bias and ADC Cards

7. Power Supply Unit

8. CamIRa PC with requisite software

9. LakeShore Temperature Controller

10. PFEIFFER Vacuum Pump

11. CTI-CRYOGENICS 8200 Compressor

B. Software Components:

1. CamIRa for ROIC operation

2. QuickIRtest for Characterization and Report Generation


3. The Standard Test Process

Setup (Automated)

There are two executables which are required to conduct automated FPA characterization using CamIRa

system:

1. ISC9705 1ch

2. QuickIRtest

The first installer ‘ISC9705 1ch’ is used to program Clock, Biases, A/D parameter etc. for Indigo 9705

ROIC and capture video from it. ‘QuickIRtest’ utility is used to automate the EO characterization and

Report Generation process.

Following is the description on operation of these utilities:

1. ISC9705 1ch – Indigo 9705 ROIC S/W Utility:

A. Bias Parameters

There are Bias generation cards available in CamIRa setup for ROIC operation purpose (Refer fig.1).

These cards can be accessed using this s/w utility to generate various clock frequency and Biases (Refer

Screenshot 1)

1. Bias 16 (VPOS/VPOSOUT, VOUTREF/VREF and VPD)

2. Bias 18 (VDETCOM, VDET_ADJ, IMSTR_ADJ and VOS)

Note: While using this utility to program ROIC, in Bias 16 Ch #1, Ch #2 and Ch #3 are enabled while in

Bias 18 only Ch #1 is enabled (Refer Screenshot 1).

Access: (Setup → Adjustable clock/bias settings → Bias 16, B1, VPOS/VPOSOUT, VOUTREF/VREF, VPD)

(Setup → Adjustable clock/bias settings → Bias 18, B2, VDETCOM, VDET_ADJ, IMSTR_ADJ, VOS)

Screenshot 1: Bias Input to ROIC 9705


B. Clock Parameters

There are clock generation cards available in CamIRa setup for ROIC operation purpose (Refer fig.1).

These cards can be accessed using this s/w utility to generate various clock frequency and Biases (Refer

Screenshot 2)

Note: While using this utility to program ROIC, in Clock 22 Ch #1, Ch #2, Ch #3 and Ch #4 are enabled

(Refer Screenshot 2).

Access: (Setup → Adjustable clock/bias settings → Clock 22, CL, DATA, FSYNC, LSYNC, CLK)

Screenshot 2: Clock Input to ROIC

C. Video Correction

For corrections in Video display such as Gray Scaling, Automatic Gain Control etc., video correction tab is

accessed:

Right Click on Video Screen → Video Correction

Screenshot 3: Video Correction in ROIC 9705


D. Offset Correction

For offset corrections in Video output, offset measurement is done at standard temperature:

Right Click on CamIRa Screen → Correction → Offset

Screenshot 4: Dark Offset Correction

E. Non-Uniformity Correction (NUC)

For Non-Uniformity corrections in Video output, offset measurement is done at two different temperatures

(Setup Low Flux –T1 Temperature and Setup High Flux –T2 Temperature)

For Eg. 25 °C (T1) and 32 °C (T2)

Right Click on CamIRa Screen → Correction → NUC

Screenshot 5: Non-Uniformity Correction


F. Video Control

For Video output controls such as Frame rate, Integration Time, A/D Input Controls: Video Offset and Gain:

Right Click on CamIRa Screen → Setup → Video Controls

Screenshot 6: Video Control in ROIC

2. ‘QuickIRtest’ EO Characterization and Report Generation Utility:

A. Start

The Electro-optic characterization for FPA is carried out by this S/W utility. Run this utility to start the

characterization process (Refer Screenshot 7).

Screenshot 7: Start of Characterization Process


B. ROIC, FPA and Blackbody Source Information

This part of characterization process takes inputs like ROIC type, FPA details and Blackbody

temperature ranges (DC High, DC Mid and DC Low) in which FPA will be characterized.

Screenshot 8: ROIC, FPA and Blackbody Source Information

C. Setup Wavelength Band, Geometry and Filter Transmission Information

This part of characterization process takes inputs like Wavelength Band, Filter Transmission and Setup

Geometry. Once it is confirmed start characterization process by pressing ‘Done’.

Screenshot 9: Setup Wavelength Band, Geometry and Filter Transmission Information


D. Setting Blackbody Temperature

The operator is prompted to confirm the blackbody temperature and press OK (Refer Screenshot 10).

Screenshot 10: Setting blackbody for specified temperature

E. Setup for DC

“Setup for DC” allows the operator to adjust integration time, bias, gain, and offset to ensure that outputs are

neither railed nor saturated at the specified blackbody temperature. The operator is prompted to confirm the

blackbody temperature and press OK (Refer Screenshot 11).

Screenshot 11: Setup for DC


After varying Offset, Gain, Bias and Integration Time, click ‘Check Setup with these settings’ to check that the

outputs are within ranges. The values are adjusted such that with specified integration time, pixel cluster

(Yellow cluster) lies in the middle dotted line and for higher and zilch integration time it lies in upper and lower

dotted line respectively (Red and Blue cluster). Keep changing Offset, Gain, Bias and Integration Time and

click ‘Check Setup with these settings’ until this condition is achieved (Refer Screenshot 12).

Screenshot 12: Setup for DC- Settings

F. Bias Sweep

“Bias sweep” - provides graphs of detector current, noise and uniformity vs bias. This allows the operator to

make an informed choice of the bias to be used for the test, the best combination of noise and uniformity. The

form also has a drag-able cursor that allows the operator to determine the average RA product for any bias of

interest (Refer Screenshot 13).

Screenshot 13: Setup for DC- Settings


Keeping blackbody at set temperature, Bias sweep is performed from most forward (6.0 V) to most reverse (8.5

V) bias condition in 26 steps. Using this single blackbody temperature measurements, bias conditions can be

selected according to desired RrA product. Drag the red cursor on the graph to select desired bias condition.

(Refer Screenshot 14)

Screenshot 14: Setup for DC- Bias Selection

But bias can also be selected by having another set of measurements of blackbody at ambient temperature

(25°C). For having another set of measurements at ambient temperature blackbody is set for ambient

temperature and by clicking ‘Sweep for Delta V’ next set of measurements is initiated (Refer Screenshot 15).

Screenshot 15: Setup for DC- Sweep for Delta ‘V’


Once the measurements are done at two different temperatures, graph can be plotted for various parameters

computed using those measurements viz. DC o/p, Uniformity, Noise N, Signal Sweep (SS-Delta DC), QE-FF,

SS/N and NEI. By selecting these parameters and using their graph, desired bias condition is selected. Usually

Signal Sweep (SS) and Signal/Noise (SS/N) is plotted and cursor is dragged to achieve higher SS/N but

moderate SS (Refer Screenshot 16).

Screenshot 16: Setup for DC- Bias selection for delta ‘V’ measurements

G. Linearity Data

“Linearity Form” – during the acquisition of DC output for three different irradiances, we can also acquire

data at many different integration times. The data are then plotted in three different ways, allowing us to

estimate the ROIC gain (for example, 150 nV/electron), the excess irradiance, the linearity, and the average

QEFF.

The software prompts user to set blackbody at specified temperature

Screenshot 17: Linearity Test (Set Temperature)

The measurement starts when user clicks ‘Start Test’ which is performed at three different blackbody

temperatures which are specified by user in ‘QT1_DewarAndFPA.xls’ file. User prompt is generated before

each of these measurements begins to ensure the set blackbody temperature is right (Refer Screenshot 18 & 19).




Three graphs are displayed in each of these measurements viz. Noise Squared vs DC Output, DC Output vs

Irradiance from Source (EBB) and DC Output vs Integrated Photons. At each of these three blackbody

temperatures, measurements are conducted and data is plotted in these graphs corresponding to each set of data.

Once all three graphs are plotted, associated line fit for each graph is completed as shown in Screenshot 20.

Screenshot 20: Linearity Test (Best Fit)


H. Setup for Noise

“Setup for Noise” – allows the operator to adjust the offset and gain to be used for the noise acquisitions.

The offset and gain is selected such that most of the pixels lie in the middle (Half well fill) dotted line for

nominal integration time.

Screenshot 21: Setup for Noise (Offset & Gain Selection)

During measurements user prompt is generated to display sampling information viz. sampling rate, frame rate,

fMax(Nyquist) and fMin. User is asked to specify no. of frames to skip, if any (Refer Screenshot 22).

Screenshot 22: Setup for Noise (Acquisition)


I. Report Preview

“Preview of the Report” – here the operator sees the defect criteria, the number of defective pixels for each of

the defect criteria, the number of clusters of each size, a map of the defective criteria, and the array means after

excluding defective pixels. The operator can change the criteria and see the results, all before printing the

report. Only when the operator is satisfied that appropriate criteria have been selected do we generate the report

(Refer Screenshot 23).

Screenshot 23: Report Preview (Defect Criteria)

Once the defect criteria are selected, measurements are conducted to compute no. of defects corresponding to

each defect criteria (Refer Screenshot 24).

Screenshot 24: Report Preview (No. of Defects)


After user clicks Count Clusters, system computes no. of clusters of different sizes (Refer Screenshot 25).

Screenshot 25: Report Preview (No. of Clusters-Different Sizes)

Lastly after all measurements system generates user prompt that the test is completed and Test Report & Test

Log file is saved (Refer Screenshot 26).


VIOLATION POLICY:

If user is not following the above mentioned procedure, the authorization/usership shall be

dismissed immediately till further consultation with Faculty incharge/Lab Manager.

TRAINING POLICY:

Due to complexity in the system operating procedure, training is currently not allowed.

Documents

FPA (Focal Plane Array) Characterization set up (CamIRa ... · For performing experimental and characterization studies on 320x256 QDIP Focal Plane Array and Indigo 9705 ROIC, a CamIRa