Differences

This shows you the differences between two versions of the page.

--- d2:laser_servo [2018/12/17 19:13] – [Reconfigurable Laser Servo] Michael Radunsky
+++ d2:laser_servo [2019/07/15 23:00] – [Laser Lock Troubleshooting] Michael Radunsky
@@ Line 185: / Line 185: @@
 **Auxiliary Servo Output**
-The AUXILIARY SERVO OUTPUT is generated from integrating the SERVO OUTPUT.  Its purpose is to supply a correction signal to drive the SERVO OUTPUT to zero. When used with Vescent DBR lasers and the D2-105 Laser Controller, the AUXILIARY SERVO OUTPUT can be connected to the TEMP SERVO IN to adjust the laser diode temperature to keep the feedback laser current constant. Similarly, AUXILIARY SERVO OUTPUT can drive a PZT on an external-cavity laser diode to keep the laser diode current constant. See [[d2:laser_servo#Aux Gain: + / Aux Gain - (2-position switch)|AUXILIARY SERVO: GAIN SIGN]] and [[d2:laser_servo#Auxiliary Servo: Gain (25-turn trimpot)|AUXILIARY SERVO: GAIN]] for information on setting the gain and and gain sign of the AUXILIARY SERVO OUTPUT.
+The AUXILIARY SERVO OUTPUT is generated from integrating the SERVO OUTPUT.  Its purpose is to supply a correction signal to drive the SERVO OUTPUT to zero. When used with Vescent DBR lasers and the D2-105 Laser Controller, the AUXILIARY SERVO OUTPUT can be connected to the TEMP SERVO IN to adjust the laser diode temperature to keep the feedback laser current constant. Similarly, AUXILIARY SERVO OUTPUT can drive a PZT on an external-cavity laser diode to keep the laser diode current constant. See [[d2:laser_servo#Aux Gain: + / Aux Gain - (2-position switch)|AUXILIARY SERVO: GAIN SIGN]] and [[d2:laser_servo#Auxiliary Servo: Gain (25-turn trimpot)|AUXILIARY SERVO: GAIN]] for information on setting the gain and gain sign of the AUXILIARY SERVO OUTPUT.
 **Ramp Offset**
@@ Line 243: / Line 243: @@
 ===Auxiliary Servo: Gain (25-turn trimpot)===
-This trimpot sets the gain for the AUXILIARY SERVO OUTPUT. The Aux Servo is a pure integrator and the gain ranges from 500 μs to 5 s.
+This trimpot sets the gain for the AUXILIARY SERVO OUTPUT. The Aux Servo is a pure integrator and the gain ranges from 500 μs to 5 s.  Full ccw sets gain to minimum (5 s), full cw sets gain to maximum (500 µs).
 <WRAP center round box 420px><imgcaption d2_125_side_panel_photo|Certain rarely used controls are only accessible by removing the right-side panel, as shown in the figure above.>
@@ Line 255: / Line 255: @@
 **	Ramp->Aux / Ramp->Servo (2-position slider switch) **
-This 2-position slider switch is only accessible by removing the right side panel (see above) and sets whether the ramp is applied to the SERVO OUTPUT or the AUXILIARY SERVO OUTPUT. It is factory set in the Ramp->Servo position. When the Ramp->Servo is selected, the ramp is a ~500Hz triangle wave and when Ramp->Aux is selected the ramp is ~50Hz. Additionally, when using The Absolute Jump TTL or the Relative Jump TTL, the output jump is placed on the same channel as gets the ramp signal. The other signal (SERVO OUTPUT or AUXILIARY SERVO OUTPUT) is held at its current value.
+This 2-position slider switch is only accessible by removing the right side panel (see above) and sets whether the ramp is applied to the SERVO OUTPUT or the AUXILIARY SERVO OUTPUT. It is factory set in the Ramp->Servo position. When the Ramp->Servo is selected, the ramp is a ~500 Hz triangle wave and when Ramp->Aux is selected the ramp is ~50 Hz. Additionally, when using The Absolute Jump TTL or the Relative Jump TTL, the output jump is placed on the same channel as gets the ramp signal. The other signal (SERVO OUTPUT or AUXILIARY SERVO OUTPUT) is held at its current value.
 ===Aux Gain: + / Aux Gain - (2-position switch)===
@@ Line 326: / Line 326: @@
 **Relative Jump TTL (BNC)**
-When asserted HIGH (5V) while in LOCK mode, RELATIVE JUMP engages a sample-and-hold circuit and takes the Laser Servo out of lock. The voltage on the SERVO OUTPUT is the sample-and-hold value summed in with the LASER JUMP AMPLITUDE. For example, if the laser is locked and the SERVO OUTPUT is -200 mV, then engaging the RELATIVE JUMP and putting 300 mV on the LASER JUMP AMPLITUDE will make the SERVO OUTPUT 100mV (-200 mV + 300 mV).  This feature is useful for jumping the laser relative to its current lock point (say +200 MHz from a locked transition). When returned to LOW (0V), the loop filter is reengaged, enabling the laser to be relocked to its original position (by setting LASER JUMP AMP to zero), or to a new lock point. (See [[http://www.vescent.com/jumping-lock-point-d2-125-reconfigurable-servo/|application note here]].) Engaging or disengaging the RELATIVE JUMP is achieved in under 400 μs.
+When asserted HIGH (5 V) while in LOCK mode, RELATIVE JUMP engages a sample-and-hold circuit and takes the Laser Servo out of lock. The voltage on the SERVO OUTPUT is the sample-and-hold value summed in with the LASER JUMP AMPLITUDE. For example, if the laser is locked and the SERVO OUTPUT is -200 mV, then engaging the RELATIVE JUMP and putting 300 mV on the LASER JUMP AMPLITUDE will make the SERVO OUTPUT 100 mV (-200 mV + 300 mV).  This feature is useful for jumping the laser relative to its current lock point (say +200 MHz from a locked transition). When returned to LOW (0 V), the loop filter is reengaged, enabling the laser to be relocked to its original position (by setting LASER JUMP AMP to zero before returning the trigger to TTL low), or to a new lock point (by asserting the trigger low with the LASER JUMP AMP still at a non-zero value). (See [[http://www.vescent.com/jumping-lock-point-d2-125-reconfigurable-servo/|application note here]].) Engaging or disengaging the RELATIVE JUMP is achieved in under 400 μs.
 When asserted HIGH (5V) while in RAMP mode, RELATIVE JUMP applies a DC offset equal to the LASER JUMP AMPLITUDE to the ramp signal at SERVO OUTPUT. When asserted LOW (0V) while in RAMP mode, the ramp signal is DC balanced.
@@ Line 375: / Line 375: @@
 If you are having problems locking the laser, it is a good idea to not use the AUXILIARY SERVO OUTPUT as this complicates the system. Once you get the locking to work properly, you can reconnect this cable.
-<imgref factory_settings> shows the nominal corner settings for locking the Vescent D2-100 to atomic spectroscopy.  If all else fails, return to these setting, turn down the gain and try again.
+<imgref factory_settings> shows and <tabref factory_setting> lists the nominal corner settings for locking the Vescent D2-100 (or a Photodigm TOSA) to atomic spectroscopy.  If all else fails, return to these setting, turn down the gain and try again.
 <WRAP center round box 400px><imgcaption factory_settings|Factory settings for locking a D2-100>
-{{ {{ d2:d2-125:factory_settings.jpg?direct&400 |}} |}}</imgcaption></WRAP>
+{{ {{ d2:d2-125:factory_settings_red.png?direct&400 |}} |}}</imgcaption></WRAP>
+<WRAP center round box 60%><tabcaption factory_setting |D2-125 locking D2-100 or TOSA>
+| **Corner**                                                       | **Value**       | **Units**  |
+| First Integrator (high freq.)                                    | low freq.       |       |
+| First Integrator (low freq.)                                     | 10              | Hz         |
+| Second Integrator (high freq.)                                   | low freq.       |       |
+| Second Integrator (low freq.)                                    | 500             | Hz         |
+| Differential (high freq.)                                        | OFF       |       |
+| Differential (low freq.)                                         | 100              | kHz         |
+</tabcaption></WRAP>
  =====D2-125 Stand-alone Test=====