FPA (Focal Plane Array) Characterization set up (CamIRa) Standard Operating Procedure FACULTY IN-CHARGE Prof. Subhananda Chakrabarti (IITB) SYSTEM OWNER Hemant Ghadi (ghadihemant16@gmail.com) 05 July 2013 CamIRa Test Setup Description and Operation Document Page 1
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 05 July 2013 CamIRa Test Setup Description and Operation Document Page 2
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. 05 July 2013 CamIRa Test Setup Description and Operation Document Page 3
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. 05 July 2013 CamIRa Test Setup Description and Operation Document Page 4
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 cos 4 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 cos 4 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 coldshield geometry. 05 July 2013 CamIRa Test Setup Description and Operation Document Page 5
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 05 July 2013 CamIRa Test Setup Description and Operation Document Page 6
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 05 July 2013 CamIRa Test Setup Description and Operation Document Page 7
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) C. Video Correction Screenshot 2: Clock Input to ROIC 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 05 July 2013 CamIRa Test Setup Description and Operation Document Page 8
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 05 July 2013 CamIRa Test Setup Description and Operation Document Page 9
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 05 July 2013 CamIRa Test Setup Description and Operation Document Page 10
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 05 July 2013 CamIRa Test Setup Description and Operation Document Page 11
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 05 July 2013 CamIRa Test Setup Description and Operation Document Page 12
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). F. Bias Sweep Screenshot 12: Setup for DC- Settings 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 05 July 2013 CamIRa Test Setup Description and Operation Document Page 13
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 05 July 2013 CamIRa Test Setup Description and Operation Document Page 14
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). G. Linearity Data Screenshot 16: Setup for DC- Bias selection for delta V measurements 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). Screenshot 18: Linearity Test (Set Temperature) 05 July 2013 CamIRa Test Setup Description and Operation Document Page 15
Screenshot 19: Linearity Test (Set Temperature) 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) 05 July 2013 CamIRa Test Setup Description and Operation Document Page 16
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) 05 July 2013 CamIRa Test Setup Description and Operation Document Page 17
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) 05 July 2013 CamIRa Test Setup Description and Operation Document Page 18
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). 05 July 2013 CamIRa Test Setup Description and Operation Document Page 19
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. 05 July 2013 CamIRa Test Setup Description and Operation Document Page 20