Scanning TCT data acquisition
Contents
1. ioe f Stage control The controlling of the stages manually is done in this tab The stage control is divided into several sectors Status defines wheatear the stage is present and on green light turned on if yes or not One can click on the StageX ON OFF to turn it on and off if the stage is present Positioning parameters Step X Y Z defines the resolution of the motor i e step size 1 8 means that position with precision of 1 8 um can be achieved Version 1 2 September 2014 Page 6 Particulars Advanced Measurement Systems Data acqusition software user manual Speed X Y Z mm s defines the speed of rotation Usually values equal or below 0 78 mm s are suitable for stage of that range Limit SW limit switch At extreme positions the stages have micro switches with break the contact and prevent further rotations of the stepping motors When the switch breaks the contact the green light turns on the corresponding side Positioning control There are two ways of moving the tables manually Either the destination position is entered in Set pos X Y Z or uses the lt and gt buttons to move for the value of Step move X left and right reset pos X the current position can be reset to become reference position 0 microns by pressing it Beware that you lose absolute calibration in this case Default speed if selected the value of the speed as it will be used in the scan see Movement parameters2. Particulars Advanced Measurement Systems Data acqusition software user manual Scanning TCT data acqusition software Introduction The software for Data Acquisition with Particulars Scanning TCT gives user a possibility to take and store large amount of waveforms usually associated with scanning TCT technique Together with a laser control software and a separate temperature controller if it requires a computer control at all it gives the user a total control of the system Installation Data acquisition software DAQ is written in Labview and runs under Microsoft Windows It requires the LabView 2010 Run Time Engine LV2010RTE to be installed on the PC The executable program called 3DTCT and LV2010RTE can be downloaded from the Particulars web page First install LV2010RTE and then decompress the 3DTCT in the folder of your choice You should be able to run 3DTCT The software can be downloaded from www particulars si downloads PSTCT zip and LVRTE from www particulars si downloads LV2010RTE zip or from National Instruments web page http ni com Notation used in this manual e Italic font name of commands in the GUI of the program controls logically belonging to the same group can be inthe same color e Bold font important e Red bold font very important not obeying the rules can result in damage to the equipment Requirements and interfaces The software controls different devices moving stages oscilloscope an
3. software Version 1 2 September 2014 Page 7 Particulars Advanced Measurement Systems Data acqusition software user manual Connected indicates that DRS board has been identified and that it is connected Frequency sets the sampling frequency in GHz 5 GHz 200ps between the time points Range range of the ADC converter 0 0 5 V to 0 5 V 1 0 V 1 V Timeout s if no trigger is received the DRS goes in the timeout and returns the control to the program The program is irresponsive for that amount of time without triggers arriving Average number of averages The speed of averaging depends on both laser pulse repetition frequency DRS board The DRS is capable of taking around 300 waveforms per second Select Channel select the channels to be acquired Trigger delay interval stored to the memory before the arrival of the trigger in ns Trigger level the only option is edge trigger with threshold given by the level in V Trigger edge trigger on falling or rising edge Trigger channel channel to trigger on DRS has a feature that the time jitter shift of pulse left and right for individual triggers can be of the order of up to 1 ns peak to peak which spoils the measured rise time of the pulses when averaging is used In order to cope with that the absolute time scale is referenced to the trigger pulse The trigger signal is very sharp and its edge can determine absolute arrival time wrt to t 0 at
4. the start of the buffer for each individual pulse tO can be set with CT and trigger threshold by CThr Time correction can be switched on off by Time corr All the settings set in the Oscilloscope tab are used for DAQ during the scans General Movement Pararneters Voltage source 1 Voltage Source 2 Stage Control Oscillascope Laser Connected Run osciloscope Take WF a Frequency Range Trigger delay i hi ll Information String from DRS i i l I I I I I I I I ri 152 667 Timeout 5 Awerage 0 250 SOQ ai 3 f Trigger lewel aE l I I I I I I I I j TERE TE Ti 0 5 0 ther oF Trigger edge Trigger Ch i Time corr CT a20 Po i P j S 4 falling i ka J on CThr f 0 45 Run oscilloscope since the application is a single threading one control to the main program should be returned by the DRS after the acquisition Therefore when running no other user operation dealing with other parts of the software is possible tabs disappear Only when the DRS board has stopped the control of the program is returned to user Version 1 2 September 2014 Page 8 Particulars Advanced Measurement Systems Data acqusition software user manual Take WF during running of the oscilloscope the waveform shown of the display Waveforms can be recorded taken to an ascii file text file You will be prompted for the filename In the first line of the file there are data and time Starti
5. FWHM of around 6 um ry T 12 amp E 2 11 10 9 8 7 6 0 50 100 150 200 250 300 350 z um Error function fit to the charge collection FWHM of the beam at at different z plots at different z coordinates coordinates Reading the measurements The data is stored in the binary form for compactness and speed reasons The software for reading in the data is based on the root root cern ch library and is available in http www particulars si TCTAnalyse index html There you will also find examples of how to read and do some analysis on taken scans Version 1 2 September 2014 Page 12 Particulars Advanced Measurement Systems Data acqusition software user manual Warning Please note that the software is in large parts in the development phase so expect some unexpected behavior and treat bugs with patience We will fix them as soon as we get them Use it only with Particulars Scanning TCT system Version 1 2 September 2014 Page 13
6. d voltage sources e Stages usually the setup comes with stages which are controlled over uSMC or Xilab after 09 2014 stage controller The original driver from the producer of the stages is recommended to be installed as well CD is a part of the shipment The stage controller is connected to the PC via USB as indicated in the installation instructions http www particulars si downloads ScanTCT _Install pdf e Osciloscope It is very difficult to include all the possible oscilloscopes in the data acquisition software In order to cover as wide range of different oscilloscopes the generic driver was written which covers different oscilloscopes from LeCroy and Textronix All of them need to communicate with the DAQ over GPIB interface GPIB In addition to GPIB Particulars added and will continue to do so more oscilloscopes also from other producers in the future for which NI VISA is used which supports different interfaces GPIB Ethernet USB RS232 If an adaptation to a specific oscilloscope is required please contact us The default option is a 4 channel 1GHz 5 GS s digitization board provided by Paul Scherer Institute Villingen Version 1 2 September 2014 Page 1 Particulars Advanced Measurement Systems Data acqusition software user manual Switzerland http www psi ch drs evaluation board which is a low cost substitution to an oscilloscope but has also some advantages over the ordinary oscilloscopes in terms of acquisi
7. der voltage 1 voltage 2 z y x After the whole scan range is done in x direction the y direction will change and after it is done z then voltage 2 and finally voltage 1 Beware as the total number of waveforms can quickly become very large Setting the reference position If only a relative position is relevant you can at any time use Stage Control Reset to set the current position as a reference ie 0 All the moves of any of the stages will be done relative to this position So 100 will mean 100 microns to the right Version 1 2 September 2014 Page 10 Particulars Advanced Measurement Systems Data acqusition software user manual However when different samples are measured on the same system it is advisable to use absolute position of the stage In order to do so run the stage to extreme position by using lt button Use the steps between 100 1000 microns and once the limit switch turns green change the step to very low value of e g 10 Press the button for moving in the opposite position gt After one or two pushes the limit switch light should disappear That indicates that the stage is in its extreme position If the reset pos is pressed this position becomes 0 Now all the moves are to few 10 microns absolutely accurate The procedure is described below By going left in steps of 100 microns the position of the stage goes from 300 to 400 to 500 When an attempt was made to go to 600 the Limit SW turns on S
8. e Switch off th j a of the VES I motors a Record channels Intialize C at m ia ize SC a A NO y Fon orri orri orr 2 Config filename Information string STOP DAQ User Sample name TK Oscilloscope Stage Controller roy PSI DRS lt i uSMC v 7 M Data file X ition 24 000 ae na T en 20 000 ET ae z position 16 000 T oo 14 000 TRAMP z oltage E 12 000 E di z 0 00 z 10 000 Voltage 2 E 8000 000 6 000 Current 1 a 0 000E 0 4 000 Current 2 000 Ta 0 000 cca 2000 22 2006 me 1 24 PM 4 000 I I I I l I Li I l I I I Li l I I I I I I I I I I l I I I I I I I I I I I I I I I I I I I l I I I I l T z 1 oo wo wo wo wo soo wo wo soo w00 99 mel Time ns Trace 2 A Time ne l 5 aan E emd Trace 3 a Movement parameters Progress 1 0 0 9 0 7 0 6 0 5 The parameters are divided into three groups Step definition Rotation and translation and Step and Speed parameters Step definitions defines the scanning range xO yO z0 are the starting positions of the tables in the frame defined by the stages dx dy dz are the step sizes in the corresponding directions Nx Ny Nz are the number of step in the corresponding directions Rotation matrix and translation transforms each step according to the formula R Mr T Version 1 2 September 2014 Page 4 Particulars Advanced Measurement Systems Data acqusiti
9. ed Measurement Systems Data acqusition software user manual 6 If you intend to do the voltage scan enter the voltage scan parameters How does it work start level stoplevel Wo steps ooo Mao an The above setting will make 11 steps from O to 100 in step of 10 V if linear mode is chosen If you would like to continue with steps of 20 V from 120 V to 500 V open a new entry in the array and enter sl start level stoplevel Mo steps azoo 700 00 cE When no voltage scan is required and you would simply want detector at given bias use the following setting in this case 80 V only ot startlevel stopleyel No steps 0 00 0 00 ef It is important that number of steps is O and start level the desired voltage If you don t care of voltage settings at all you can also disable voltage sources but then no current and voltage information will be written to the file The default setting for applying the bias Inc speed Inc bias Delay after bias are usually adequate Please pay attention to current compliance setting as too high value can lead to destruction of the sensor in case of the breakdown 7 Once the voltage and position stepping has be determined DRS oscilloscope set one can proceed with data acquisition To do than press START You will be able to monitor the progress and taken waveforms during the scan The direction of the scan changing the parameters is always done in the following or
10. es no sense to have motors powered for additional day without doing anything Init motors at start initializes motors at the start User user taking the data Sample name name of the sample Type of generation laser used I temperature Comment all the additional info that needs to be stored The above information will be stored in the header of the data file Make sure that you enter all the information before you start DAQ Information string message display for the data from the devices Clears with botton C next to it Config filename name of the configuration file Data file name of the data file START starts the data acquisition STOP DAQ stops the data acquisition If pressed the missing data in the file will be replaced with O so that the file will still be useable Waveforms shows the last taken waveform during data acquisition x y Z current positions of the stages Voltage 1 Voltage 2 Current 1 Current 2 bias voltage and current for both sources Progress shows the progress of the acquisition and the estimated time until it is finished Version 1 2 September 2014 Page 3 Particulars Advanced Measurement Systems General Movement Parameters Voltage Source 1 Voltage Source 2 Stage Control Oscilloscope Laser Info Data acqusition software user manual p i Comment Scope GPIB Type of generation tommen RED 658 nm Y VISA resource nam
11. gs should be done directly on the oscilloscope 3 When changing the voltage please use if possible the Voltage source 1 2 tabs To change the voltage during the manual tuning of parameters focus search setting up the laser power duration enter the value in Output bias voltage and press Apply bias now The voltage source must be initialized first 4 To move stages to desired location before the start of the scan and manually check signals at different positions use Stage Control tab First make sure that stages you want to operate are switched on Stage Control StageX ON OFF If you initialize stages at the start then they should be on The position of the stages returned by the software upon initialization can be arbitrary Therefore it is always advisable to set the reference position before performing any scans See instruction for Setting reference position If stages are in appropriate position already one can use either Stage Control lt gt buttons or put the required position in microns and move the tables It is generally good idea to have Stage Control Refresh scope turned on so that the effect of the movement to the signal can be immediately seen Although the step and speed of the movement can be controlled the default values are general found acceptable 5 Once the range of investigated positions is located enter the data in the Movement Parameters tab Version 1 2 September 2014 Page 9 Particulars Advanc
12. ng time and time difference between the data points are in the second line Then the taken waveforms follow in columns one for each active channel Running the software This chapter is a step by step introduction how to prepare parameters and run a simple scan 1 Once the application is opened press in the top left corner of the window This start the program The first step would usually be the initialization of the devices General Init Devices Make sure that the devices you want to initialize have initialization at start switched on voltage sources DRS board stages If initialization was successful you can setup the scanning and data acquisition parameters It is recommended that if you frequently do similar equal scans that you record the parameters to a file General Save General Load Two examples of classic TCT measurement defocused beam on a pad detector without position scanning and position scan with a single voltage source are included in the distribution Parameters ClassicalTCT dat Parameters ScanningTCT dat Have a look at the files to understand the configuration syntax 2 It is always advisable to check that waveform acquisition works Oscilloscope Run Oscilloscope For what you are going to record is exactly what is shown in Waveforms If DRS is used you can also adjust the parameters within the program These options are disabled trigger averaging settings when an oscilloscope is selected for acquisition The settin
13. o from a file This is very useful as it saves time to setup parameters and prevent small mistakes each time the program starts For example the parameters for a certain type of scan can be saved and then reloaded Save Yes No enables the saving of the taken waveforms to the disk Usually no is chosen only to test if everything works Byte order data are stored in the binary form and this parameter controls the byte order in which bytes of a float variable are written O decided by the OS 1 Little Endian 2 Big endian It is recommended to use option 2 which is also set as default Oscilloscope selects the appropriate oscilloscope connected to the computer NI VISA resource name selects the oscilloscope s VISA address Scope GPIB GPIB address of the oscilloscope only if GPIB without NI VISA is used Record Channels Select which channels of the oscilloscope you would like to record This is useful for a multi channel TCT where more amplifiers are connected to the same detector Up to 4 channels can be simultaneously recorded Version 1 2 September 2014 Page 2 Particulars Advanced Measurement Systems Data acqusition software user manual Stage Controller select the stage controller USMC is default Switch off motors disconnects the power to the motors after the scan is finished This serves to prolong the lifetime of the motors e g for a scan started on Friday and completed on Saturday it mak
14. on software user manual where R represents the position in the detector frame M rotation matrix and T translation vector This is useful if coordinate system of the detector is not the same as the one of the stages The default seting is T 0 0 0 and M 1 General Movement Parameters Voltage Source 1 l Voltage Source 2 l Stage Control l Oscilloscope Laser Movement speed Movement step Step 0 1 8 1 1 4 2 1 2 3 1 Usually the default settings are recommended If large areas are scanned some time can be saved by increasing the speed of the movement at the expense of more accurate positioning Time between steps determines the time the stages are at rest after the move before the waveforms are taken Ideally this value can be 0 s but 0 1 s would be recommended to be certain that stages to be really at rest when the waveforms are taken Voltage Source 1 2 Bias Source 1 controls whether the source is connected If not all the other options are ignored in the program Voltage Source selects the device used as bias source Initialize at start decides whether the device is initialized when Init Devices is pressed Output bias V set the desired bias voltage The value will be applied after Apply bias now is pressed Initialize now initializes device reconfigures if some configuration settings have been changed manually Steping control Voltage source 1 2 The first array of three fields sta
15. rt bias stop bias number of voltages in between determines the stepping in certain voltage interval Several intervals can be defined by using the array Please read section on running the software for clarification Mode determines how the array of voltage steps will be defined linear exponential and both options with hysteresis Version 1 2 September 2014 Page 5 ie Particulars Advanced Measurement Systems Data acqusition software user manual Inc speed s defines the speed with which the voltage is changed during ramping up down the bias voltage Inc bias V defines what is the bias step that is used during ramping up down the bias voltage e g if itis 5 V that means that the bias step of 20 V will be done in 4 steps each 5 V with a delay of determined by Inc speed s between each step Delay after bias s defines the delay after the bias step before the current measurement is taken Some detectors need certain time before the current stabilizes Current Control Voltage source 1 2 Range defines the range of the current Current Comp A current compliance That is important to prevent the damage to the sensor in case of the electrical breakdown Average internal number of current measurements done internally by the device sometimes called filter Average external number of current measurements averaged in the DAQ software GPIB address address of the voltage source
16. tch of 50 um and strip width 10 um For the purpose of the study all strips are connected together not always the case 1 Crude focus finding position the laser in x direction so that the signal at given z is minimal That should happen when you hit the metalized strip If you are completely out of focus there will be no dependence at all Move in crude steps the optics z axis and look for it 2 Once you see the change in the signal as you move along the x axis or y if differently oriented start changing in smaller step position of the optics The point where the minimal signal is observed has the correct focal distance Version 1 2 September 2014 Page 11 Particulars Advanced Measurement Systems Data acqusition software user manual 3 Runa scan in very appropriate steps in x and z with fixed voltage to find precise focus What you should get is illustrated below for the red laser The signal as a function of o o the laser position along the axis perpendicular to the Strips with detector place Charge arb co 500 in the focus of the red laser a00 If the optics is moved in any directions the 300 transitions become less sharp as shown below The 200 error function is usually fit to the signal in the 100 transition region from which the FWHM of the 0 20 40 60 g0 400 beam is calculated FWHM y um of the beam at different positions of the optics shows a nice Gaussian profile of the beam with
17. tep move X was changed to 10 microns and a sometimes gt needs to be pushed twice step was made in the right direction The position reported by the software is 493 which means that at 503 microns is the extreme position After that the reset pos X was pressed and the current location of the table becomes position 0 in x The same should be repeated for all axis Limit SW Set pos X Limit SW Set pos X Limit SW Set pos X F 300 F p 500 Step move X Aoo SiE Ena Jo Step move X Afo Limit SW Set pos X Limit SW Set pos X Set pos X Xx i 492 56 Step move X afo Step move X Ao Step move X A 10 This is useful for focus finding with different detectors mounted If the samples are of similar size the stages can be moved to approximate focus position see installation instruction for focus information and only fine tuning is required Even if the samples are different one can calculate expected position of the focus from geometry of the mount Focus finding Focus finding is one of the main tasks that will be performed with the setup It is essential for taking high quality data To find focus detectors need to be metalized with metallization dimensions larger than FWHM of the beam almost always the case or during Edge TCT scans with well defined edge of the detector in the sense that light is not reflected from the surface serving as support for the detector Let us assume that we want to find focus on a strip detector with pi
18. tion rate and portability e Voltage sources the data acquisition program controls perform scans with one or two voltage sources used for biasing detectors samples The list of voltage sources built in the software includes most widely used models by Keithley 228 237 487 617 2410 6487 6517 As in the case of oscilloscopes please contact us for adaptation to another voltage source Again the GPIB interface is used for communication with the PC Structure of the software The software is written in such a way that it should be as easy as possible to operate it Different functionalities are grouped in the individual tabs General Movement Parameters Voltage Source 1 Voltage Source 2 Stage Control and Oscilloscope Laser control is foreseen in the 3DTCT but not yet implemented Apart from the General tab all other tabs are designated to control and setup specific piece of hardware In Voltage Source 1 for example one sets the stepping parameters for the bias voltage scan initializes the source sets the current compliance parameters etc The review of the functions of individual tabs will follow General parameters Description of controls Init devices initializes the stage drivers voltage sources DRS board if chosen Initialization is a requirement to be able to start scanning acquisition It is usually performed right after the start of the program Save Load saves loads the set of parameters of the control panels t
19. will override Speed X Y Z mm s Refresh scope it will perform acquisition of the waveform after the movement of the stages Set as Start when pushed the values of current x y and z positions are written to Movement Parameteres Step definitions x0 y0 and ZO Stage move after setting the destination Set pos X Y Z pushing the button moves the stages to the designated positions starting with x axis then y axis and finally z axis General l Movement Parameters Voltage Source 1 Voltage Source 2 Stage Control Oscilloscope Laser Info Status Positioni Positioning control Reset StageX Limit SW Set pos X a E aNa ra StepX ija gt SpeedX mm s 0 78 Ul Li i 2 Stage ON OFF Step Y 4 9 ae i Speed Y mms 0 78 E ad ad 0 1 8 1 4 1 2 1 0 00238 6 25 ie im i2 i eee 6 25 Step move X 12 Step move Y 2 Se Set pos Z A SENAN i 8 SpeedZ mm s 078 E 0 1 8 1 4 1 2 1 0 00238 6 95 Step move Z a2 Oscilloscope The oscilloscope tab is mostly used when PSI DRS board is used When using the classical oscilloscope the data acquisition software only transfers the waveform shown in the oscilloscope to the PC All the settings regarding trigger averaging dynamic range time scale etc should be done in the oscilloscope Only the waveforms to be taken are indicated in the software In case of DRS is used which unlike the oscilloscope has no display all the required settings are done within the DAQ
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