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d2:laser_controller [2020/09/11 23:19] Michael Radunskyd2:laser_controller [2024/03/27 15:33] (current) – Captilizing Rth_RTN to match table. Thomas Bersano
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 [[http://www.vescent.com/products/electronics/d2-105-laser-controller/|D2-105 web page]] [[http://www.vescent.com/products/electronics/d2-105-laser-controller/|D2-105 web page]]
  
-===== Description: =====+==== Description: ====
  
-The laser controller has two temperature controllers capable of sub-mK stability(( Sub-mK stability requires a proper thermal design and proper tuning of the temperature controller to the thermal plant. If you did not purchase a D2-100 Diode Laser with your Laser Controller, please read the section on tuning the temperature controller.)) and a 200 mA or 500 mA precision current source based on the Libbrecht-Hall(( Libbrecht and Hall, A Low-Noise, High-Speed Current Controller, Rev. Sci. Inst. 64, pp. 2133-2135 (1993).)) circuit.  The laser controller is designed for very fast current modulation via the servo input enabling high-speed servo control of the laser's frequency.  The current servo input can accommodate input frequencies over 10 MHz and is limited by  the 1 kΩ input impedance. Additionally, an RF port is available for higher frequency modulation.+The laser controller has two temperature controllers capable of sub-mK stability((Sub-mK stability requires a proper thermal design and proper tuning of the temperature controller to the thermal plant. If you did not purchase a D2-100 Diode Laser with your Laser Controller, please read the section on tuning the temperature controller.)) and a 200 mA or 500 mA precision current source based on the Libbrecht-Hall(( Libbrecht and Hall, A Low-Noise, High-Speed Current Controller, Rev. Sci. Inst. 64, pp. 2133-2135 (1993).)) circuit.  The laser controller is designed for very fast current modulation via the servo input enabling high-speed servo control of the laser's frequency.  The current servo input can accommodate input frequencies over 10 MHz and is limited by  the 1 kΩ input impedance. Additionally, an RF port is available for higher frequency modulation.
  
 <WRAP center round important 60%>The range of pole settings for the T2 temperature control loop (diode temperature control) for D2-105 Laser Controllers with Serial Number 2675 and higher (Temperature Control Board Serial Number 6987 and higher) have been modified to allow the user to more easily control a low thermal mass laser assembly such as a Photodigm TOSA.  Please use the appropriate instructions in the "Tuning the Temperature Controller" section of this manual for your Laser Controller and laser type. <WRAP center round important 60%>The range of pole settings for the T2 temperature control loop (diode temperature control) for D2-105 Laser Controllers with Serial Number 2675 and higher (Temperature Control Board Serial Number 6987 and higher) have been modified to allow the user to more easily control a low thermal mass laser assembly such as a Photodigm TOSA.  Please use the appropriate instructions in the "Tuning the Temperature Controller" section of this manual for your Laser Controller and laser type.
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 As with __any__ diode laser and controller, improper usage can cause irreparable damage to the diode. As with __any__ diode laser and controller, improper usage can cause irreparable damage to the diode.
 </WRAP> </WRAP>
 +
 <WRAP center round important 60%> <WRAP center round important 60%>
 If you are considering using an Uninterruptible Power Supply (UPS) to guarantee operation of your Vescent products through a brown out or black out, great care should be taken in choosing the model.  Lower cost models tend to produce modified square wave voltage profiles.  The high-frequency components of such a voltage profile may interact poorly with the D2-005 (and down-stream active Vescent modules).  If you do choose to use a UPS, select a model that will provide a sine wave voltage profile without higher harmonic components to avoid potential damage to your high-value equipment. If you are considering using an Uninterruptible Power Supply (UPS) to guarantee operation of your Vescent products through a brown out or black out, great care should be taken in choosing the model.  Lower cost models tend to produce modified square wave voltage profiles.  The high-frequency components of such a voltage profile may interact poorly with the D2-005 (and down-stream active Vescent modules).  If you do choose to use a UPS, select a model that will provide a sine wave voltage profile without higher harmonic components to avoid potential damage to your high-value equipment.
 </WRAP> </WRAP>
  
 +<WRAP center round important 60%>
 +Both temp control loops can be toggled with a board-level switch located under the PID tuning switches. If you are experiencing problems with either of your temp loops, please toggle this switch off and then on again, as it's possible for the switch to get bumped into an intermittent position where it looks on, but is off. The most common symptom of this issue is that the faulty temp loop's front panel LED will turn red, but this does not always happen.
 +</WRAP>
  
-===== Purchase Includes: =====+==== Purchase Includes: ====
 <WRAP group> <WRAP group>
 <WRAP half column> <WRAP half column>
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 </WRAP></WRAP> </WRAP></WRAP>
  
-===== Absolute Maximum Ratings =====+==== Absolute Maximum Ratings ====
 Note: All modules designed to be operated in laboratory environment Note: All modules designed to be operated in laboratory environment
 <WRAP center round box 60%> <WRAP center round box 60%>
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 </WRAP> </WRAP>
  
-=====Specifications=====+====Specifications====
 <WRAP center round box 550px> <WRAP center round box 550px>
 ^                                                                                                                                                                                                                                                                                                                                                                ^  D2-105      D2-105-500  ^  Units   ^ ^                                                                                                                                                                                                                                                                                                                                                                ^  D2-105      D2-105-500  ^  Units   ^
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 </WRAP> </WRAP>
  
-===== Inputs, Outputs, and Controls =====+==== Inputs, Outputs, and Controls ====
  
 [{{ :d2:d2-105:d2-105-frontback-diagram.png?nolink&900 |Front and Back Panel of D2-105}}] [{{ :d2:d2-105:d2-105-frontback-diagram.png?nolink&900 |Front and Back Panel of D2-105}}]
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 When the switch is in the Off/Reset position, the laser diode is turned off and the laser is shorted to ground. When flipped into the On position, the Laser ON (LED indicator) will turn on and 5s later, the laser will turn on. If the laser diode is turned off from the laser enable or remote interlock, this switch must to placed into the Off/Reset position and then into the ON position to turn the laser back on. When the switch is in the Off/Reset position, the laser diode is turned off and the laser is shorted to ground. When flipped into the On position, the Laser ON (LED indicator) will turn on and 5s later, the laser will turn on. If the laser diode is turned off from the laser enable or remote interlock, this switch must to placed into the Off/Reset position and then into the ON position to turn the laser back on.
  
-Neither the laser nor the Laser ON (LED indicator) will not turn on if any of the following conditions are true:+Neither the laser nor the Laser ON (LED indicator) will turn on if any of the following conditions are true:
   - The remote interlock is not engaged   - The remote interlock is not engaged
   - The key interlock is not engaged   - The key interlock is not engaged
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 T1 is also set at the factory and should not require further adjustment.  However, the T1 trimpot can be accessed by removing the right panel from the enclosure.  Note: Before attempting to set the set point temperature, you must connect a thermal plant to the D2-105.  If you do not have a plant attached to the temperature loop, the set point range will appear to be limited to less than ~12°C. T1 is also set at the factory and should not require further adjustment.  However, the T1 trimpot can be accessed by removing the right panel from the enclosure.  Note: Before attempting to set the set point temperature, you must connect a thermal plant to the D2-105.  If you do not have a plant attached to the temperature loop, the set point range will appear to be limited to less than ~12°C.
 +
 +<WRAP center round important 60%>
 +Both temp control loops can be toggled with a board-level switch located under the PID tuning switches (see <imgref standby_switch>). If you are experiencing problems with either of your temp loops, please toggle this switch off and then on again, as it's possible for the switch to get bumped into an intermittent position where it looks on, but is off. The most common symptom of this issue is that the faulty temp loop's front panel LED will turn red, but this does not always happen.
 +</WRAP>
 +
 +<imgcaption standby_switch|The location of the control switches for T1 and T2.>{{ :d2:d2-105:standby_switch_loation.jpg?600 |}}</imgcaption>
  
 **Temp Lock (Dual position switch)** **Temp Lock (Dual position switch)**
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 The temperature servo input is summed to the T2 temperature set point signal and can be used to make electronic perturbations to the laser diode temperature.  The Temp Servo Input, has two settings: "Low" and "High" gain. The default settings is "Low" but can be changed by a switch accessible on the right side panel. See <imgref VPN00267>. The temperature servo input is summed to the T2 temperature set point signal and can be used to make electronic perturbations to the laser diode temperature.  The Temp Servo Input, has two settings: "Low" and "High" gain. The default settings is "Low" but can be changed by a switch accessible on the right side panel. See <imgref VPN00267>.
 +
 +
 +
  
 <WRAP center round box 570px><imgcaption VPN00267|Temp control board with T2 Temp Servo Input gain switch circled>[{{ d2:d2-105:vpn00267.gif?nolink&550 | filler text }}]</imgcaption></WRAP> <WRAP center round box 570px><imgcaption VPN00267|Temp control board with T2 Temp Servo Input gain switch circled>[{{ d2:d2-105:vpn00267.gif?nolink&550 | filler text }}]</imgcaption></WRAP>
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 **Laser Temp Output (8-pin connector)** **Laser Temp Output (8-pin connector)**
  
-An 8-pin Hirose connector (see <tabref TECconnectortable> for identity of connectors) carries the signals for the temperature control of the Laser module.  The wiring diagrams are shown in <tabref TEC_connector_pinout> below, where 1 (2) refer to stage 1 (2) temperature control, which stabilizes the Laser Housing (Laser Diode). Rth and Rth_Rtn are the two ends of a 10 kΩ [[http://www.analogtechnologies.com/ath10kr8.html|Analog Technologies ATH10KR8 Thermistor]].+An 8-pin Hirose connector (see <tabref TECconnectortable> for identity of connectors) carries the signals for the temperature control of the Laser module.  The wiring diagrams are shown in <tabref TEC_connector_pinout> below, where 1 (2) refer to stage 1 (2) temperature control, which stabilizes the Laser Housing (Laser Diode). Rth and Rth_RTN are the two ends of a 10 kΩ [[http://www.analogtechnologies.com/ath10kr8.html|Analog Technologies ATH10KR8 Thermistor]].
  
 <WRAP round center box 230px><tabcaption TEC_connector_pinout| TEC connector pin out> <WRAP round center box 230px><tabcaption TEC_connector_pinout| TEC connector pin out>
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 {{ :d2:d-sub_power_pinout.jpg?nolink&150 |}} {{ :d2:d-sub_power_pinout.jpg?nolink&150 |}}
  
 +While it is infrequent, the D2-005 power supply may occasionally radiate noise from the side of its chassis onto nearby electronics. This only occurs in some system configurations, and will appear as a signal at the frequency of your mains electricity (typically either 50 Hz or 60 Hz). This noise can easily be removed by moving the D2-005 at least 18 inches (45cm) away from other electronics, rotating it 90° such that the sides of the D2-005 face away, or by moving the entire power supply to a different shelf. To accommodate this, all D2-005's are shipped with a 5' DB9 cable as of January 1, 2022. 
  
 **Laser Enable** **Laser Enable**
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 **Remote Interlock** **Remote Interlock**
  
-The remote interlock can be used to disable the laser diode output via an interlock control.  When this input is shorted the laser diode output is ON.  When the input is open the diode output is OFF.  If not used, leave a shorting cap over this BNC. Once the interlock has been tripped, the laser will stay off until it is manually reset with the front panel switch.+The remote interlock can be used to disable the laser diode output via an interlock control.  When this input is shorted the laser diode output is ON.  When the input is open the diode output is OFF.  If not used, leave a 50Ω BNC terminator over this BNC. Once the interlock has been tripped, the laser will stay off until it is manually reset with the front panel switch.
  
 **Setpoint In** **Setpoint In**
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 The Servo Input on the front panel continues to function when the SETPOINT ENABLE is pulled low.  Only the Coarse and Fine Current Adjustments are disabled. The Servo Input on the front panel continues to function when the SETPOINT ENABLE is pulled low.  Only the Coarse and Fine Current Adjustments are disabled.
  
-=====Turning on the Laser Diode=====+====Turning on the Laser Diode====
  
 In compliance with FDA requirements for a Class 3B laser, the Laser Controller has two safety interlocks. If either interlock is tripped, the laser will turn off and stay off until the interlocks are reset AND the laser switch is switched from the "off / reset" position to the "on" position. Additionally, if the Laser Controller loses power, the laser diode will remain off when power is restored. In compliance with FDA requirements for a Class 3B laser, the Laser Controller has two safety interlocks. If either interlock is tripped, the laser will turn off and stay off until the interlocks are reset AND the laser switch is switched from the "off / reset" position to the "on" position. Additionally, if the Laser Controller loses power, the laser diode will remain off when power is restored.
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 <WRAP center round important 60%>The range of pole settings for the T2 temperature control loop (diode temperature control) for D2-105 Laser Controllers with Serial Number 2675 and higher (Temperature Control Board Serial Number 6987 and higher) have been modified to allow the user to more easily control a low thermal mass laser assembly such as a Photodigm TOSA.  Please use the appropriate instructions below for your Laser Controller. <WRAP center round important 60%>The range of pole settings for the T2 temperature control loop (diode temperature control) for D2-105 Laser Controllers with Serial Number 2675 and higher (Temperature Control Board Serial Number 6987 and higher) have been modified to allow the user to more easily control a low thermal mass laser assembly such as a Photodigm TOSA.  Please use the appropriate instructions below for your Laser Controller.
 +
 +If you purchased the -FL option for your D2-105, then the T1 loop has the same available pole settings as the T2 loop of controllers with Serial Number 2675 and higher.
 </WRAP> </WRAP>
  
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   - Measure the resistance across GND5 and probe point GAIN2. Set this resistance to between 1.2 kΩ and 1.4 kΩ by adjusting trimpot PROPGAIN2.   - Measure the resistance across GND5 and probe point GAIN2. Set this resistance to between 1.2 kΩ and 1.4 kΩ by adjusting trimpot PROPGAIN2.
  
-<WRAP center round box 570px><imgcaption factory_set_post6987|Factory settings of T2 (left) and T1 (right) poles for units with S/N 2675 or higher (PCBs with S/N 6987 and higher)>[{{ :d2:d2-105:temp_loop_post_sn_6987_w_text.png?nolink&550 | filler text }}]</imgcaption></WRAP>+<WRAP center round box 570px><imgcaption factory_set_post6987|Factory settings of T2 (left) and T1 (right) poles for units with S/N 2675 or higher (PCBs with S/N 6987 and higher)>[{{ :d2:d2-105:Modern_Corners.jpg?nolink&550 | filler text }}]</imgcaption></WRAP>
  
 <WRAP center round box 60%><tabcaption factory_set2_post6987|Factory settings of T2 Proportional poles (first DIP switch in figure) and T2 Differential poles (second DIP switch in figure) for units with S/N 2675 or higher (PCBs with S/N 6987 and higher)> <WRAP center round box 60%><tabcaption factory_set2_post6987|Factory settings of T2 Proportional poles (first DIP switch in figure) and T2 Differential poles (second DIP switch in figure) for units with S/N 2675 or higher (PCBs with S/N 6987 and higher)>
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 To get good temperature stability, the temperature servo response needs to be tuned to match the thermal load. Access to tuning the temperature response is provided on the right side panel of the Laser Controller and requires removing that side panel to access the controls. The Laser Controller provides two independent temperature controllers that are nominally identical. However, stage 2 has front panel adjustment of the temperature set-point, while the stage 1 temperature set-point is a side-panel adjustment. Additionally, the front panel TEMP SERVO INPUT adjusts the stage 2 set-point while stage 1 does not have an equivalent function. Stage 2 is accessed in the middle of the side-panel, while stage 1 is near the back of the side panel. Typically, stage 2 is used to control the laser temperature and stage 1 is used to control the temperature surrounding stage 2.  In this way temperature gradients between the laser diode and the thermistor measuring the laser temperature are stabilized and temperature changes caused by room temperature drift are greatly reduced.  To get good temperature stability, the temperature servo response needs to be tuned to match the thermal load. Access to tuning the temperature response is provided on the right side panel of the Laser Controller and requires removing that side panel to access the controls. The Laser Controller provides two independent temperature controllers that are nominally identical. However, stage 2 has front panel adjustment of the temperature set-point, while the stage 1 temperature set-point is a side-panel adjustment. Additionally, the front panel TEMP SERVO INPUT adjusts the stage 2 set-point while stage 1 does not have an equivalent function. Stage 2 is accessed in the middle of the side-panel, while stage 1 is near the back of the side panel. Typically, stage 2 is used to control the laser temperature and stage 1 is used to control the temperature surrounding stage 2.  In this way temperature gradients between the laser diode and the thermistor measuring the laser temperature are stabilized and temperature changes caused by room temperature drift are greatly reduced. 
  
-====Transfer Function and Poles====+===Transfer Function and Poles===
  
 Each stage of temperature control has a transfer function shown below: Each stage of temperature control has a transfer function shown below:
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 <imgcaption side_adjustb|Side Panel Adjustment of Poles for D2-105>{{:d2:d2-105:temppoles4.jpg?nolink&300}}</imgcaption> <imgcaption side_adjustb|Side Panel Adjustment of Poles for D2-105>{{:d2:d2-105:temppoles4.jpg?nolink&300}}</imgcaption>
 </WRAP> </WRAP>
-====User Control of the Poles and Gain====+===User Control of the Poles and Gain===
  
 If you remove the right side panel on the Laser Controller, for each stage of temperature control, you will see the panel shown in <imgref side_adjustb>. The set of click switches labeled "Integral" controls the PI (ω<sub>1</sub>) pole. <color black/yellow>Clicking the first switch, labeled "proportional," into the on position removes the integral gain (but not the differential gain). If the "proportional" switch is in the off position (integral gain is now on), then the sum of the times for all switches in the on position gives the RC time-constant for the PI pole.</color> For example, if the 2<sup>nd</sup> (0.47s) switch and the 4<sup>th</sup> (2.2s) switch are in the on position (and the rest off), then the time constant is 2.7s and ω<sub>1</sub> = 1/2.7s = 0.37 Hz.  If you remove the right side panel on the Laser Controller, for each stage of temperature control, you will see the panel shown in <imgref side_adjustb>. The set of click switches labeled "Integral" controls the PI (ω<sub>1</sub>) pole. <color black/yellow>Clicking the first switch, labeled "proportional," into the on position removes the integral gain (but not the differential gain). If the "proportional" switch is in the off position (integral gain is now on), then the sum of the times for all switches in the on position gives the RC time-constant for the PI pole.</color> For example, if the 2<sup>nd</sup> (0.47s) switch and the 4<sup>th</sup> (2.2s) switch are in the on position (and the rest off), then the time constant is 2.7s and ω<sub>1</sub> = 1/2.7s = 0.37 Hz. 
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-====Tuning the Thermal Loop====+===Tuning the Thermal Loop===
  
 Although there are numerous methods for tuning the loop parameters, these instructions will use the Ziegler-Nichols tuning method. Although there are numerous methods for tuning the loop parameters, these instructions will use the Ziegler-Nichols tuning method.
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 //NOTE: Depending on the thermal design, nested temperature loops can fight each other, causing oscillations and instability. If you observe this, you will need to reduce the gain and/or increase the time-constants on the slower stage. // //NOTE: Depending on the thermal design, nested temperature loops can fight each other, causing oscillations and instability. If you observe this, you will need to reduce the gain and/or increase the time-constants on the slower stage. //
  
-====Tuning Temperature Loop for Photodigm Mercury Lasers====+===Tuning Temperature Loop for Photodigm Mercury Lasers if you have an older D2-105=== 
 +If you have a D2-105 with S/N 2674 or lower (PCBs with S/N 6986 and lower), then you may still be able to tune the parameters of the loop to stably control the temperature of the TOSA by following the protocol below:
  
 If you are using the D2-105 laser controller to drive a Photodigm Mercury laser in a TOSA package, the following may be helpful as a starting point for setting the thermal control loop parameters.((Courtesy of [[http://www.photodigm.com|Photodigm]]))  Refer to <imgref side_adjustb>. If you are using the D2-105 laser controller to drive a Photodigm Mercury laser in a TOSA package, the following may be helpful as a starting point for setting the thermal control loop parameters.((Courtesy of [[http://www.photodigm.com|Photodigm]]))  Refer to <imgref side_adjustb>.
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 If the Temperature with the above TIME settings begins to run away, then quickly turn the “PROPGAIN” Potentiometer CCW until it stabilizes. If the Temperature with the above TIME settings begins to run away, then quickly turn the “PROPGAIN” Potentiometer CCW until it stabilizes.
 +
 +We use [[https://www.photodigm.com|Photodigm]] Spectroscopy-Certified<sup>TM</sup> DBR lasers. \\
 +[[https://www.photodigm.com|{{:d2:d2-100:photodigm_logo.png?direct&200|}}]]
 +
d2/laser_controller.1599866395.txt.gz · Last modified: 2021/08/26 14:26 (external edit)