1. Manuals
  2. Brands
  3. Toptica Manuals
  4. Measuring Instruments
  5. Digilock 110
  6. Manual

Toptica Digilock 110 Manual

Feedback controlyzer
Hide thumbs Also See for Digilock 110:
Table of Contents

Advertisement

Quick Links

Download this manual
Digilock 110
Feedback
Controlyzer
Manual: M-031 Version 02
Copyright
T
OPTICA
Lochhamer Schlag 19
D-82166 Graefelfing/Munich
Tel.: +49 89 85837-0
Fax: +49 89 85837-200
email: info@toptica.com
http://www.toptica.com
(October 2008 Subject to changes without notice)
Manual
2008 T
Photonics AG
OPTICA
Photonics AG

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the Digilock 110 and is the answer not in the manual?

Questions and answers

Subscribe to Our Youtube Channel

Related Manuals for Toptica Digilock 110

Summary of Contents for Toptica Digilock 110

  • Page 1 Digilock 110 Feedback Controlyzer Manual Manual: M-031 Version 02  Copyright 2008 T Photonics AG OPTICA Photonics AG OPTICA Lochhamer Schlag 19 D-82166 Graefelfing/Munich Tel.: +49 89 85837-0 Fax: +49 89 85837-200 email: info@toptica.com http://www.toptica.com (October 2008 Subject to changes without notice)
  • Page 3 Feedback Controlyzer DigiLock 110 Dear Customer, welcome to the T community! OPTICA We have designed this product to be easy to use and reliable so that you can focus on your actual work. Should you anyway have questions regarding its use or need advice on how to integrate it into your setup, please do not hesitate to ask.

  • Page 5: Table Of Contents

    Scope Mode 6.3.2 AutoLock Mode 6.3.3 Frequency Analysis Status Display Notes on Feedback Control Loops with the DigiLock 110 Signal to Noise and Bandwidth Considerations Frequency Modulation Techniques Controller Parameter Adjustment and Optimization Identification of Signal Polarity and Slope Relock Feature Signal Limitations in Analyzing the Locking Performance Status: 21.10.08...
  • Page 6 8.2.2 Top of Fringe Locking (Lock-In) Pound-Drewer-Hall Stabilization to a Cavity Appendix Internal Jumpers DigiLock 110 PCBs 9.2.1 Baseboard 9.2.2 Plug-On Board Specifications of DigiLock 110 Connections Pin Assignment of the DigiLock 110 Backplane 10 Guarantee and Service Status: 21.10.08...

  • Page 7: The Feedback Controlyzer Digilock 110

    So far the different schemes require a corresponding set of adapted electronics. The DigiLock 110 integrates fast analog and digital electronics into a versatile general purpose locking module. Its up-to-date digital hardware allows to implement the scan generator, PID controllers and optional frequency modulation techniques all into one plug-in module.

  • Page 8: Design And Operating Principle Of The Digilock 110

    Feedback Controlyzer DigiLock 110 Design and Operating Principle of the DigiLock 110 Figure 1 Schematic Block Diagram of the DigiLock 110 Module Page 4 Status: 21.10.08...
  • Page 9 1. The Feedback Controlyzer DigiLock 110 Figure 2 Schematic Block Diagram of the DigiLock 110 Functional Units and their Interaction Figure 3 Schematic Block Diagram of the Connections to the DC 110 Backplane Page 5 Status: 21.10.08...

  • Page 10: Safety Instructions And Warnings

    In addition, a NOTE ! heading provides information to the user that may be beneficial in the use of the instrument. DANGER ! Before operating the DigiLock 110 plug-in module please read this manual carefully to CAUTION ! prevent from damage to the electronics, connected diode lasers and injury to persons. The following safety instructions must be followed at all times.

  • Page 11: Identification Of Manufacturer

    2. Safety Instructions and Warnings Identification of Manufacturer Manufacturer (name and address), serial number, article number, compliance with CE standards are given by the identification label: Size: 46 mm x 25 mm Color: Silver/black Location: Rear Panel of the plug-in module Page 7 Status: 21.10.08...

  • Page 12: Operator Controls And Connections

    Feedback Controlyzer DigiLock 110 Operator Controls and Connections Front Panel Figure 4 Front Panel of the DigiLock 110 1 ON/OFF switch and indicator 6 Main out 11 General purpose digital input/ high-speed analog output output 2 Precise analog input 7 Aux out...

  • Page 13: Description Of Front Panel Operator Controls And Connectors

    Description of Front Panel Operator Controls and Connectors Range [V] Impedance [Ω] 1 ON/OFF Switch ON/OFF Switch for the • Switch and LED DigiLock 110 module. 2 Precise analog input Precision analog input ± 2 V • SMB-connector 3 Aux in high-speed analog input...

  • Page 14: Backplane Connections

    Before installation, switch off all other modules and disconnect the supply rack from the mains supply. The DigiLock 110 can be plugged into any slot of a 19’’ or 12’’ rack, except the one reserved for the DC 110/Mon on the right.

  • Page 15: Software Installation

    USB-Driver Installation The DigiLock 110 provides a USB connection to load the firmware and to control the module via the sup- plied PC based software. In order to communicate with the DigiLock 110, the USB driver has to be installed before the installation of the application software.

  • Page 16: Operation Frontend

    Visit www.toptica.com for information about the most recent software version. The DigiLock 110 frontend consists of two main areas and a status bar. In the upper part of the screen the user can set the appropriate operation parameters for the chosen function. The lower part is used to dis- play various signals by the means of an oscilloscope or a spectrum analyzer.

  • Page 17: General User Interface

    6. Operation Frontend General User Interface To operate the software efficiently it is necessary to be familiar with the user interface. Some helpful remarks are presented in the following: • Changing numeric input controls Set the focus on the desired numeric control (left click on the field). A cursor appears in the input field.
  • Page 18 Feedback Controlyzer DigiLock 110 • Graph Display: Setting the scale of a graph When the dynamic range scaling option is deactivated, the limits of the scaling of an axis can be modified manually. To change the lower/upper limit click on the value in the graph and modify it by typing a new value.

  • Page 19: Functions

    6. Operation Frontend Functions In the upper part of the screen all the available functions and options of the DigiLock 110 are displayed on different layers. With the buttons on the left hand side you can select the desired function and then browse the corresponding options and parameters.
  • Page 20 Feedback Controlyzer DigiLock 110 6.2.1.3 AutoLock Figure 9 AutoLock The AutoLock tab is used in combination with the “AutoLock Mode” display (see Paragraph 6.3.2) in the lower part of the screen. This mode combines the controllers and enables the user to interactively search for the desired locking point, select it and lock the system (“click and lock”).
  • Page 21 6. Operation Frontend 6.2.1.4 PID 1 Figure 10 PID 1 Controller The PID 1 is a standard PID controller with the special feature that the user can set a frequency below which the integral part is limited (as illustrated by the transfer function, Paragraph 6.2.2). This limitation of the integral part is important in case PID 1 is used together with PID 2 in one control system.
  • Page 22 Feedback Controlyzer DigiLock 110 General: These parameters are intended to manually operate the controller. In the AutoLock mode these parameters are set automatically. Since the interactive AutoLock covers most standard locking situations, the man- ual options should only be needed in special cases.
  • Page 23 Figure 12 Analog P In order to overcome the signal delay introduced by digital signal processing, the DigiLock 110 features a very fast analog path. Its high bandwidth allows the experienced user to achieve further improvements in particularly demanding locking situations. Note that an improvement of the lock relies on a corre- spondingly high actuator and detection bandwidth.
  • Page 24 Feedback Controlyzer DigiLock 110 6.2.1.7 Lock-In-Module Figure 13 Left: Lock-in Module Tab Right: Error Signal generated with the Lock-In Modulation Technique The Lock-In-Module can be used to generate an error signal for the PID controller with the Lock-in-modu- lation/demodulation scheme. Since it generates the derivative of the original signal, it allows the user to stabilize a system to a peak or a valley.
  • Page 25 6. Operation Frontend 6.2.1.8 PDH-Module Figure 14 Left: PDH Module Tab Right: Error Signal generated with the Pound-Drever-Hall Modulation Technique The principle of operation is similar to the Lock-In-Module but the available modulation frequencies are higher and restricted to even fractions of 25 MHz (25 MHz, 12.5 MHz, 6.25 MHz, 3.13 MHz, 1.56 MHz). Input: Input source for the module (Main in, Aux in).

  • Page 26: Controller Design

    Feedback Controlyzer DigiLock 110 6.2.2 Controller Design Figure 15 Controller Design This function visualizes the transfer function of the selected PID controller according to the parameters chosen. The transfer function graph consists of two traces: the magnitude and the phase which are plot- ted versus the frequency.

  • Page 27: Network Analysis

    6. Operation Frontend 6.2.3 Network Analysis Figure 16 Network Analysis In order to determine the dynamic behavior of a system, it is a common strategy to perform a network analysis. The result of such an analysis is the transfer function of the device under test (DUT) defined by the amplitude and phase values with respect to the frequency of the stimulus.

  • Page 28: System Setup

    Figure 17 System Setup Schematic of the high-speed signal path inside the DigiLock 110 module. Some parameters can only be set on this screen (<Main in> input offset, <Main in> gain, invert signal, all kinds of filters). All parameters set here are automatically updated throughout the whole system.

  • Page 29: Settings

    6. Operation Frontend 6.2.5 Settings The settings layer enables the user to access additional options of the DigiLock 110. It is divided into the following four tabs: 6.2.5.1 PID On this tab all advanced parameters for the PID modules can be found.
  • Page 30 Feedback Controlyzer DigiLock 110 6.2.5.2 LI/PDH Figure 19 LI/PDH Tab on the Settings Layer Modulation signal type: Type of the waveform used for modulation and demodulation. First filter notch (LI-Module): The LI-Module only works properly if a low-pass filter is applied to the demodulated signal in order to filter frequency components located at the modulation frequency.
  • Page 31 Figure 21 General Tab on the Settings Layer Ask to upload firmware By default the firmware of the DigiLock 110 is uploaded at startup of the at startup: software. This upload takes some seconds and resets the module. During a module reset, all analog output channels are set to 0 V before they are loaded with the values specified in the interface software.
  • Page 32 Feedback Controlyzer DigiLock 110 6.2.5.6 Profiles NOTE ! Loading profiles is only possible if the PID controllers are off (see Status display). The user can save and load profiles. A profile is a set of system parameters, e.g. all settings of the different modules, display settings, etc.

  • Page 33: Display Area

    6. Operation Frontend Display Area The lower part of the screen shows three different displays that are accessible through the buttons on the left hand side. 6.3.1 Scope Mode Figure 25 Scope Mode Display Two channel digital oscilloscope to display different available system signals. CH 1: Signal displayed on channel 1.

  • Page 34: Autolock Mode

    Feedback Controlyzer DigiLock 110 6.3.2 AutoLock Mode Figure 26 AutoLock Mode Display This display is used in conjunction with the AutoLock tab in the upper part of the screen. In this mode the user can handle two major tasks: • Search the desired point to lock to via panning and zooming the displayed signal.

  • Page 35: Frequency Analysis

    6. Operation Frontend 6.3.3 Frequency Analysis Figure 27 Frequency Analysis Display The frequency analysis displays the fast fourier transform (FFT) of the signal. The functionality is similar to the scope mode but in the frequency domain. NOTE ! The selected frequency range defines the sampling rate of the signal used for the FFT. CH 1: Signal displayed on channel 1.

  • Page 36: Notes On Feedback Control Loops With The Digilock 110

    In case of the digital filters in the DigiLock 110 the phase lag is due to additional signal delay. For most cases it is hence recommended to bypass the digital input filters in the System Setup (Paragraph 6.2.4).

  • Page 37: Controller Parameter Adjustment And Optimization

    The output of the controller is a weighted sum of the integral (I), proportional (P) and differential (D) paths scaled by the overall gain. The digital PIDs in the DigiLock 110 allow for a precise and reproducible control of the gain settings.

  • Page 38: Identification Of Signal Polarity And Slope

    Otherwise the direction has to be determined for the particular actuator used. For example, if the DigiLock 110 scan module scans the laser via the Scan Control SC 110 and the output of PID 2 is also cho- sen to be the SC 110, its polarity is trivially positive. If the output of PID 1 is then directed to the current of the laser diode, the polarity of the controller will depend on the polarity of the laser diode as defined by the DCC 110 current control (see Sys DC 110 manual for details).
  • Page 39 7. Notes on Feedback Control Loops with the DigiLock 110 Figure 29 Polarity of PID Controller for Side of Fringe Lock The graph shows the characteristic distortions of the error signal of a side of fringe lock for dif- ferent polarities. The displayed example is a zoom into the saturated absorption spectros- copy of Rb.

  • Page 40: Relock Feature

    Relock Feature The basis of the relock feature of the DigiLock 110 is the out of lock detection. It is based on a window comparator which is defined by the minimum and maximum bounds. The laser is considered in lock when the signal of the selected channel is within these bounds (100 % window).

  • Page 41: Signal Limitations In Analyzing The Locking Performance

    This effect is well known from digital oscilloscopes. In the case of the DigiLock 110 there is an additional effect to be observed for sampling rates well below the Nyquist frequency (especially using PDH modulation): Due to the complete synchrony of the sampling with the applied modulation the undersampled signal can show as a (noisy) line at a finite off- set that varies from shot to shot.

  • Page 42: Application Examples

    Typical Setup for Laser Locking The signal from the photo detector (PD) is fed into the <Main in> input of the DigiLock 110. The two PID controllers act via the backplane and SC 110 on the grating piezo and via the <Main out>...
  • Page 43 DC 110 Monitor Unit Connect the output of the Scan Control SC 110 to the piezo of the ECDL. Since the DigiLock 110 provides the scan capability set the trigger switch on the front panel of the SC 110 to position ext (external).
  • Page 44 SC 110 as a high voltage amplifier. The output is the sum of the voltage specified in the DigiLock 110 software and the offset of the SC 110. The SC 110 offset can hence additionally be used to scan the laser.
  • Page 45 8. Application Examples Figure 33 DigiLock 110 User Interface after Startup. Here, the laser is scanned across the saturated absorption lines of Rb at 780.24 nm, see Paragraph 8.2. Figure 34 Graphical Overview of the Signal Path through the Controller (System Setup) The System Setup function (Figure 34) shows a block diagram of the control loop.
  • Page 46 Feedback Controlyzer DigiLock 110 Name Description Standard Value Input offset offset to be subtracted from the input signal 0.0 V before digitalization to use the full resolution of the analog-to-digital converter (ADC) Gain gain to amplify the signal. The maximum range is...

  • Page 47: Doppler-Free Saturation Spectroscopy

    To scan the laser with the piezo, use the Scan Module control box of the DigiLock 110 Control Soft- ware. Select <SC 110 out> as output, set the signal type to triangle, the frequency to 10 Hz and the amplitude in the order of 10 Volts.

  • Page 48: Side Of Fringe Locking

    Once the laser scans across the spectral feature two different locking schemes can be implemented using the AutoLock feature of the DigiLock 110. First locking to the side of a fringe is presented (Para- graph 8.2.1) then the use of frequency modulation/demodulation to lock to a maximum or minimum is explained (Paragraph 8.2.2).
  • Page 49 8. Application Examples First the AutoLock is activated and the controllers PID 1 and PID 2 are selected by checking the corresponding boxes (see Figure 37). PID 1 will handle the high frequencies (by controlling the laser current via the modulation option in the laser head) whereas PID 2 will be responsible for the lower frequencies by controlling the piezo voltage.
  • Page 50 Feedback Controlyzer DigiLock 110 To configure the PID controllers, select the PID 1/PID 2 tab to access the corresponding parame- ters (see Figure 40). In AutoLock operation the input channel of the PIDs is defined by the AutoLock input. PID 1 is used for the high frequency feedback, therefore its output channel is <Main out>...
  • Page 51 8. Application Examples Figure 41 Initiating the AutoLock to a slope of the absorption signal Figure 42 Autolock Display while the lock is engaged (PID: lock to slope) After some time the yellow trace disappears and a scatter plot is left which indicates both the input signal (y-axis) and the current output of the PID 2 which in this case coincides with the scan (see Figure 43) on the x-axis.
  • Page 52 Feedback Controlyzer DigiLock 110 Figure 43 AutoLock Display after the lock has been triggered. The yellow scatter plot indicates signal input and regulator output (PID 2) Parameter optimization: To obtain a “good“ lock it is necessary to increase the gain settings of the PID controllers to the highest possible values without oscillations.

  • Page 53: Top Of Fringe Locking (Lock-In)

    1/10 of the characteristic linewidth. In this example a frequency of about 100 kHz is used. Due to the specific architecture of the DigiLock 110 only discrete frequencies are possible. Type in the desired one and the system will automatically calculate the nearest one available (Mod act freq).
  • Page 54 Feedback Controlyzer DigiLock 110 Name Description Value to set to Input signal input to be demodulated <Main In> Mod set freq modulation set frequency is the user selected 100 [kHz] modulation frequency Mod act freq modulation act frequency is automatically set to the...
  • Page 55 8. Application Examples Once the phase is adjusted, turn off the modulation of the Lock-In-Module. Check the parameters of the PID controllers. Now you can position the crosshairs to either a peak or a valley and it will automatically track the lock point. To find the correct settings of the sign for each PID controller, please see Paragraph 7.4 To initiate the lock, perform a right mouse click to access the context menu and select between LI/PDH: Lock to nearest peak or LI/PDH: Lock to nearest valley.
  • Page 56 Feedback Controlyzer DigiLock 110 Figure 47 Initiating the automatic LI-lock to a Peak Select the lock point by positioning the crosshairs. When the Lockpoint tracker is on, it snaps to the nearest peak or dip and if the laser drifts the lock point is tracked automatically. Acti- vate the lock by selecting LI/PHD: Lock to nearest peak/valley from the context menu.

  • Page 57: Pound-Drewer-Hall Stabilization To A Cavity

    Experimental Setup of a Pound-Drewer-Hall (PDH) Stabilization to a Cavity. Note that the modulation is directly added to the <Main out> channel of the DigiLock 110. Alternatively the modulation can be applied to the mod AC input of the DLpro.
  • Page 58 Feedback Controlyzer DigiLock 110 The parameters of the PDH-Module are analogous to the LI-Module and are listed in the following table. Name Description Value to set to Input signal input to be demodulated <Main In> Mod set freq modulation set frequency can be selected for a set of 12.5 [MHz]...
  • Page 59 8. Application Examples Figure 51 AutoLock Display of the reflection signal of a Fabry-Perot Cavity (upper yellow trace) with the corresponding PDH-Signal (lower red trace) 18a. The phase between the modulation and the reference signal has to be adjusted to obtain a large, symmetric error signal with steep slopes at the maximum of the spectral signal.
  • Page 60 Feedback Controlyzer DigiLock 110 Figure 52 Initiating the automatic PDH-Lock to a Valley Figure 53 AutoLock display after triggering the lock (LI/PDH: Lock to nearest valley) Page 56 Status: 21.10.08...

  • Page 61: Appendix

    Appendix Internal Jumpers The DigiLock 110 module is shipped with a standard configuration of its inputs and outputs. The internal jumpers allow to modify this configuration. The table below shows all jumpers and their function. For loca- tion of the jumpers please see Figure 55 and Figure 56.

  • Page 62: Digilock 110 Pcbs

    Feedback Controlyzer DigiLock 110 DigiLock 110 PCBs 9.2.1 Baseboard Figure 55 DigiLock 110 Jumpers on Baseboard Page 58 Status: 21.10.08...

  • Page 63: Plug-On Board

    9. Appendix 9.2.2 Plug-On Board Figure 56 DigiLock 110 Plug-On Board Page 59 Status: 21.10.08...

  • Page 64: Specifications Of Digilock 110 Connections

    Feedback Controlyzer DigiLock 110 Specifications of DigiLock 110 Connections Power Supply Value Supply Voltage +-15 V Supply Current 700 mA +15V (max) Supply Current 200 mA -15V (max) Input Resolution Sample Bandwidth Range Input Comment Channel [bit] Rate [Hz] (- 3dB) [Hz]...

  • Page 65: Pin Assignment Of The Digilock 110 Backplane

    9. Appendix Pin Assignment of the DigiLock 110 Backplane Actual pins needed for normal operation of the DigiLock 110 Module are marked with a grey back- ground color. (VG-64-a/b/c standard connector according to IEC 60603-2) Figure 57 VG-64-a/b/c Standard Connector...

  • Page 66: Guarantee And Service

    Feedback Controlyzer DigiLock 110 Guarantee and Service To obtain information concerning factory service, contact your local distributor or T Photonics AG OPTICA directly. On the following pages you find the Guarantee Registration Form and the Service and Technical Support Form.
  • Page 67 Model No.: ____________________ Date: ________________________ Serial No.: ____________________ Signature: ________________________ Date of Delivery: ____________________ Name/Title: ________________________ To be completed by the buyer and returned to TOPTICA Photonics AG by mail or fax (+49 - 89 – 85837 – 200). Version: 01/02-05...
  • Page 69 6HUYLFH DQG 7HFKQLFDO 6XSSRUW )RUP ) 6WDWXV RI IRUP   RI  40 IRUP 9HUVLRQ  3DJH 5HWXUQ WR 6HQGHU 7237,&$ 3KRWRQLFV $* BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB &XVWRPHU 6HUYLFH BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB /RFKKDPHU 6FKODJ  BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB '  *UDHIHOILQJ0XHQFKHQ BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB *HUPDQ\ BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB )$;       5HWXUQ $XWKRUL]DWLRQ QXPEHU 50$  9%  B B B B B B %HIRUH JRRGV DUH UHWXUQHG SOHDVH DVN WKH...

Table of Contents