d2:laser_controller
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d2:laser_controller [2019/08/29 17:20] – Michael Radunsky | d2:laser_controller [2022/02/11 17:40] – external edit 127.0.0.1 | ||
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[[http:// | [[http:// | ||
- | ===== 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 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. |
<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 " | <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 " | ||
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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 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. | 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. | ||
</ | </ | ||
+ | <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. | ||
+ | </ | ||
- | ===== Purchase Includes: | + | ==== Purchase Includes: ==== |
<WRAP group> | <WRAP group> | ||
<WRAP half column> | <WRAP half column> | ||
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</ | </ | ||
- | ===== 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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</ | </ | ||
- | =====Specifications===== | + | ====Specifications==== |
<WRAP center round box 550px> | <WRAP center round box 550px> | ||
^ ^ D2-105 | ^ ^ D2-105 | ||
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</ | </ | ||
- | ===== Inputs, Outputs, and Controls | + | ==== Inputs, Outputs, and Controls ==== |
[{{ : | [{{ : | ||
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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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<WRAP center round tip 80%> | <WRAP center round tip 80%> | ||
- | If the LED indicator does not turn on when the Laser ON-OFF/ | + | If the LED indicator does not turn on when the Laser ON-OFF/ |
If the LED indicator turns on for ~5 seconds and then turns off, check your laser diode connection to see if it is open (or if the diode is backwards). | If the LED indicator turns on for ~5 seconds and then turns off, check your laser diode connection to see if it is open (or if the diode is backwards). | ||
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T1 is also set at the factory and should not require further adjustment. | T1 is also set at the factory and should not require further adjustment. | ||
+ | |||
+ | <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. | ||
+ | </ | ||
+ | |||
+ | < | ||
**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 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. | ||
+ | |||
+ | |||
+ | |||
<WRAP center round box 570px>< | <WRAP center round box 570px>< | ||
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**Laser Temp Output (8-pin connector)** | **Laser Temp Output (8-pin connector)** | ||
- | An 8-pin Hirose connector (see <tabref TECconnectortable> | + | An 8-pin Hirose connector (see <tabref TECconnectortable> |
<WRAP round center box 230px>< | <WRAP round center box 230px>< | ||
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{{ : | {{ : | ||
+ | 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, | ||
**Laser Enable** | **Laser Enable** | ||
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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 " | 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 " | ||
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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. | ||
</ | </ | ||
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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>< | + | <WRAP center round box 570px>< |
<WRAP center round box 60%>< | <WRAP center round box 60%>< | ||
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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, | 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, | ||
- | ====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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< | < | ||
</ | </ | ||
- | ====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> | + | 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> |
Similarly, the switches labeled " | Similarly, the switches labeled " | ||
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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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- Turn on temperature loop. | - Turn on temperature loop. | ||
- Adjust set-point to approximately desired temperature. | - Adjust set-point to approximately desired temperature. | ||
- | - Turn up the gain. Keep increasing the gain until the temperature error (front panel BNC) just start to oscillate or ring with very little damping. If oscillation too large, reduce gain. Measure the period of oscillation. | + | - Turn up the gain. Keep increasing the gain until the temperature error (front panel BNC) just starts |
- Turn off the Laser Controller. Measure resistance between " | - Turn off the Laser Controller. Measure resistance between " | ||
- Take the measured oscillation period in step 6 and divide by two. Set the Integrator time constant to this value. For instance, if you measured a period of oscillation of 14 seconds, turn on the 4< | - Take the measured oscillation period in step 6 and divide by two. Set the Integrator time constant to this value. For instance, if you measured a period of oscillation of 14 seconds, turn on the 4< | ||
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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 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:// | 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:// | ||
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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:// | ||
+ | [[https:// | ||
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d2/laser_controller.txt · Last modified: 2024/03/27 15:33 by Thomas Bersano