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Kentech Instruments Pockels cell Driver Instructions For Use Manual

Pockels cell driver for ase suppression
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Kentech Instruments Ltd.
Pockels cell Driver for ASE suppression
Instructions For Use
Serial Numbers ....
27-10-2014
PLEASE READ THIS MANUAL CAREFULLY
BEFORE USING THE DRIVERS OR POCKELS CELLS
Kentech Instruments Ltd.,
Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
Tel: +44 (0) 1491 82 1601
E-mail info@kentech.co.uk
Web http://www.kentech.co.uk/

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Summary of Contents for Kentech Instruments Pockels cell Driver

  • Page 1 Kentech Instruments Ltd. Pockels cell Driver for ASE suppression Instructions For Use Serial Numbers ..27-10-2014 PLEASE READ THIS MANUAL CAREFULLY BEFORE USING THE DRIVERS OR POCKELS CELLS Kentech Instruments Ltd., Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 2: Table Of Contents

    OPTICAL TESTS OF UNIT J1405141-1 ..................... 37 8.18 TESTS ON THE PHOTODIODE ......................... 42 REPORTS OPTICAL TESTING REPORT ........................42 RADIAL PROBING MEASUREMENTS ....................49 POCKELS CELL SETUP AND ALIGNMENT Kentech Instruments Ltd., Page 2 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...
  • Page 3 The rising edge at various radial positions with normalised amplitude........51 Figure 20 Plot showing the relative timing and signal amplitude as a function of radial position ....52 Kentech Instruments Ltd., Page 3 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 4: Disclaimer

    Kentech Instruments Ltd. accepts no responsibility for any electric shock or injury arising from use or misuse of this equipment. It is the responsibility of the user to exercise care and common sense with this highly versatile equipment.

  • Page 5: Overall Description

    The unit has three modes of operation plus a “debug” mode. The state into which the unit powers up is set by these modes and the storage of a previous state of the unit. Kentech Instruments Ltd., Page 5 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 6 Figure 1 Overall picture of unit Kentech Instruments Ltd., Page 6 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K 27-10-2014.

  • Page 7: Leds

    Should the fuse fail we recomend that it be replaced no more than once and that the type indicated in the specifications is used. If it should fail a second time return the unit to the factory. Kentech Instruments Ltd., Page 7 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 9: Signage

    Lockout power before servicing. Hazardous voltages at the indicated connector. Do not touch. Figure 3 Signs used on the equipment, see Figure 2 on page 8 Kentech Instruments Ltd., Page 9 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...

  • Page 10: General Description Of System

    The pulser is of a design unique to Kentech Instruments Ltd. It comprises many avalanche transistors delivering a single output that is shaped to give an optimum optical signal when used with a suitable pockels cell.

  • Page 11: Jitter

    “8.13 MODES” on page 25. As supplied the unit will be in mode 0 and it will only be possible to enable the unit if the load is sufficiently low. Kentech Instruments Ltd., Page 11 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 12: Pockels Cell

    If necessary the unit can be made to enable at power up or to behave in other ways. This is discussed in section “8.13 MODES” on page 25 Kentech Instruments Ltd., Page 12 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 13: Software Interface

    Ethernet receiver and the embedded computer. In case they are changed by accident the main parameters are as follows: baud rate 9600 serial port 1 10001 flow control off 8 data bits no parity 1 stop bit Kentech Instruments Ltd., Page 13 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...

  • Page 14: Using Device Installer

    Click on the device that has an MAC address that matches that on the rear panel of the unit and then select “Assign IP”. The following will appear. Enter the MAC address of the unit into the requested field and hit next. Kentech Instruments Ltd., Page 14 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 15 Decide if a fixed or automatically assigned IP address is needed and check the relevant box. Then hit Next. Kentech Instruments Ltd., Page 15 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...
  • Page 16 If you select fixed IP address a window will open to allow you to set it. If you select assign IP address automatically, the following will appear. Select DHCP and then hit Next. In the following window hit Assign. Kentech Instruments Ltd., Page 16 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...
  • Page 17 The set up of the IP address is now complete. Quit Device Installer and launch a terminal program. The following assumes that Hyperterminal will be used. When Hyperterminal is launched the following window will be displayed. Kentech Instruments Ltd., Page 17 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 18 Fill in the IP address derived from Device Installer into the Host Address field, The port number should be set to 10001 and the “connect using” set to TCP/IP (Winsock) as above. Kentech Instruments Ltd., Page 18 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 19: Typical Operation

    The software can also control the speed of the fans and disable them entirely. This state is also stored in the user profile. Kentech Instruments Ltd., Page 19 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 20: The Enable Logic

    All status commands expect and deliver data as decimal numbers and all numeric data should be decimal, no decimal points or other punctuation to be used. For example (note cr in the following means type a carriage return): Kentech Instruments Ltd., Page 20 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 21: Multiple Commands On One Line

    Name @amplitude Explanation read desired value for pulse voltage Format @amp parameter 1 none returned value desired value in 0 to 4095 arbitrary units. Kentech Instruments Ltd., Page 21 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...

  • Page 22: Pulser Triggering

    Note that the command may not be successful, this will depend upon the mode setting and any fault setting. This is why there is a returned value. Name @enable Explanation read enable status Kentech Instruments Ltd., Page 22 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...

  • Page 23: Personality

    Ready latch, -1 = ready, 0 = not ready returned value 3 Enabled latch, -1 = enabled, 0 = not enabled returned value 4 Pulser fault latch, -1= fault, 0 = no fault Kentech Instruments Ltd., Page 23 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...

  • Page 24: Control

    Name resetuser Explanation restore factory settings Format 0usr [That is a zero] parameter 1 none returned value none Note Factory setting are the following: Kentech Instruments Ltd., Page 24 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...

  • Page 25: State Of Unit At Delivery

    The most important is the Load High flag as a high load can cause excessive voltages on the pockels cell. Consequently mode 2 should only be used with care. Kentech Instruments Ltd., Page 25 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 26: Saving The Machine State

    Out1b = 3867 lo = 3704 hi = 5000 t0 = 3898 Out2b = 3870 lo = 3704 hi = 5000 t0 = 3898 Out3b = 3860 lo = 3699 hi = 5000 t0 = 3893 Kentech Instruments Ltd., Page 26 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 27 Load lo = 0 ok The expected range for each response is indicated as the lo or hi figure and the factory value as the t0 figure. Kentech Instruments Ltd., Page 27 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 28: Test Waveforms Electrical

    (20db) and an Agilent DSO81004B 10GHz oscilloscope. 8.16.1 ELECTRICAL TESTS OF UNIT J1405141-1 Figure 4 Timing jitter with electrical triggering of unit J1405141-1, showing 4.3ps SD, 30.1ps range over 654 shots. Kentech Instruments Ltd., Page 28 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...
  • Page 29 This shape has been optimised during optical transmission tests and is different from the electrical optimisation carried out previously. In particular the initial over shoot presumably helps overcome the rise time limitations of the cell. Kentech Instruments Ltd., Page 29 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 30 This shape has been optimised during optical transmission tests and is different from the electrical optimisation carried out previously. In particular the initial over shoot presumably helps overcome the rise time limitations of the cell. Kentech Instruments Ltd., Page 30 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 31 Figure 7 Timing jitter with electrical triggering of unit J1405141-2, showing 4.6ps SD, 29.5ps range over 999 shots. Kentech Instruments Ltd., Page 31 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...
  • Page 32 Monitor output J1405141-2 8000 6000 4000 2000 Time ns Figure 8 Monitor output for unit J1405141-2. This gives approximately 1000:1 Kentech Instruments Ltd., Page 32 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...
  • Page 33 This output has reduced bandwidth compared to monitoring the output pulse with Barth Attenuators. Also this pulse has propagated through the cell and its cabling. Kentech Instruments Ltd., Page 33 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...
  • Page 34 The step before the pulse is an artefact of the oscilloscope. The red and blue curves are the required performance envelopes. The result indicates that the post pulse signal is a little high. Kentech Instruments Ltd., Page 34 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 35 Figure 10 on page 34 The red and blue curves are the required performance envelopes. The result indicates that the pulse is flat to the required specification. Kentech Instruments Ltd., Page 35 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 36 The red and blue curves are the required performance envelopes. The result indicates that the pulse almost rise meets the required specification with a slight issue in the first 50ps after the 10% level. Kentech Instruments Ltd., Page 36 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 37: Test Waveforms Optical

    The step before the pulse is an artefact of the oscilloscope. The red and blue curves are the required performance envelopes. The result indicates that the post pulse signal is a little high. Kentech Instruments Ltd., Page 37 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 38 Figure 13 on page 37 The red and blue curves are the required performance envelopes. The result indicates that the pulse is flat to the required specification. Kentech Instruments Ltd., Page 38 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 39 The red and blue curves are the required performance envelopes. The result indicates that the pulse almost rise meets the required specification with a slight issue in the first 50ps after the 10% level. Kentech Instruments Ltd., Page 39 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 40 FO modulator. The ripples at 2.5 and 3.5 ns are known artefacts of the AWG. The clean impulse shape is indicative of a clean response from the diode. Kentech Instruments Ltd., Page 40 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 41 FO modulator. The ripples at 2.5 and 3.5 ns are known artefacts of the AWG. The clean step shape is indicative of a clean response from the diode. Kentech Instruments Ltd., Page 41 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 42: Tests On The Photodiode

    Whilst we knew the oscilloscope was not a perfect instrument, in particular there are ripples just before a step, we have discovered that it has a precursor to a step that lasts several ns. Kentech Instruments Ltd., Page 42 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 43 I strongly recommend that something of this nature is done as the long cables offer the possibility of applying an enormous torque to the existing clamps. Kentech Instruments Ltd., Page 43 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 44 Kentech Instruments Ltd., Page 44 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...
  • Page 45 The following measurements have been made with the Driver output voltage set to 3800 on a scale of 0 through 4095. These are arbitrary units and the scale is not linear. Kentech Instruments Ltd., Page 45 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 46 Kentech Instruments Ltd., Page 46 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...
  • Page 47 Note that by increasing the voltage the leading peak is reduced, so at 4095 the half wave voltage is certainly being achieved. Optimum flatness is probably at a setting of around 4000. Kentech Instruments Ltd., Page 47 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 48 The electrical measurements, modified for the sin squared response of the cell, indicate that the transmission should be well below 10 of the peak transmission if the static extinction ratio is as good as this. Kentech Instruments Ltd., Page 48 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...

  • Page 49: Radial Probing Measurements

    The cell was mounted on a precision translation stage. The optical beam was set up normally to give high extinction using the isogyre pattern. The rising edge timing and relative transmission was then recorded as a function of radial position. Kentech Instruments Ltd., Page 49 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.

  • Page 50: Pockels Cell Setup And Alignment

    The basic alignment configuration is shown below. Modulator Between Crossed Polarisers Kentech Instruments Ltd., Page 50 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...
  • Page 51 Position of axis of scan in mm across the aperture -0.5 normalised amplitude -200 -150 -100 Time ps Figure 19 The rising edge at various radial positions with normalised amplitude. Kentech Instruments Ltd., Page 51 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...
  • Page 52 Plot showing the relative timing and signal amplitude as a function of radial position The signal has been averaged to remove laser mode structure, this also helps remove timing jitter. Kentech Instruments Ltd., Page 52 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 53 The extra polariser, if one was used, may be removed. Kentech Instruments Ltd., Page 53 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K.
  • Page 54 Kentech Instruments Ltd., Page 54 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...
  • Page 55 Kentech Instruments Ltd., Page 55 Isis Building, Howbery Park, Wallingford, Oxfordshire, OX10 8BA, U.K. 27-10-2014...

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