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| d2:laser_servo [2019/10/24 16:39] – [Lock Guard] Michael Radunsky | d2:laser_servo [2020/03/18 16:39] – [Right Side Panel] Michael Radunsky |
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| The D2-125 Reconfigurable Laser Servo contains a tunable PI<sup>2</sup>D loop filter for tight locking to an error signal. The error signal is either an amplified version of the Error Input signal (side-lock mode) or an amplified version of a demodulated Error Input (optional peak-lock mode). In both modes, a DC Offset is summed to the error signal, allowing the user to select the zero-crossing and thus the lock point. The error signal can also be inverted via a front-panel switch. Additionally, the Laser Servo has an internal ramp generator for sweeping the output and computer control functionality to make and break lock and directly control the output voltage. | The D2-125 Reconfigurable Laser Servo contains a tunable PI<sup>2</sup>D loop filter for tight locking to an error signal. The error signal is either an amplified version of the Error Input signal (side-lock mode) or an amplified version of a demodulated Error Input (optional peak-lock mode). In both modes, a DC Offset is summed to the error signal, allowing the user to select the zero-crossing and thus the lock point. The error signal can also be inverted via a front-panel switch. Additionally, the Laser Servo has an internal ramp generator for sweeping the output and computer control functionality to make and break lock and directly control the output voltage. |
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| The main component in the Reconfigurable Laser Servo is the PI<sup>2</sup>D loop filter, which means that the feedback has standard proportional (P), integral (I), and differential (D) feedback with a second integral feedback (I) providing the PI<sup>2</sup>D transfer function. The double integration is used to boost gain at low frequencies. With integrator frequencies tunable from 2 MHz down to 10 Hz, the Laser Servo can be optimized to a wide variety of plants and servo loops. With the Peak Lock option, the Laser Servo can demodulate a provided 4 MHz dither signal to enable slope-detection for locking to signal minimas and maximas. The Laser Servo can be used to lock a laser's current or PZT to an interferometer or an optical transition. With peak-lock, the Laser Servo can perform Pound-Drever-Hall (PDH) locking to an optical cavity. The Reconfigurable Laser Servo uses basic voltage inputs and outputs. As a result, it can be used with lasers or with any voltage-tunable device with an error signal. | The main component in the Reconfigurable Laser Servo is the PI<sup>2</sup>D loop filter, which means that the feedback has standard proportional (P), integral (I), and differential (D) feedback with a second integral feedback (I) providing the PI<sup>2</sup>D transfer function. The double integration is used to boost gain at low frequencies. With integrator frequencies tunable from 2 MHz down to 10 Hz, the Laser Servo can be optimized to a wide variety of plants and servo loops. With the Peak Lock option, the Laser Servo can demodulate a provided 4 MHz dither signal to enable slope-detection for locking to signal minima and maxima. The Laser Servo can be used to lock a laser's current or PZT to an interferometer or an optical transition. With peak-lock, the Laser Servo can perform Pound-Drever-Hall (PDH) locking to an optical cavity. The Reconfigurable Laser Servo uses basic voltage inputs and outputs. As a result, it can be used with lasers or with any voltage-tunable device with an error signal. |
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| The Laser Servo can be unlocked by a computer (via TTL control) to jump the output voltage to a set voltage difference from the current lock point, or to a specific voltage. This feature can be used to jump the laser frequency a known distance away and then relock to the original or a new lock point frequency. This feature can be used for auto-locking or relocking routines. | The Laser Servo can be unlocked by a computer (via TTL control) to jump the output voltage to a set voltage difference from the current lock point, or to a specific voltage. This feature can be used to jump the laser frequency a known distance away and then relock to the original or a new lock point frequency. This feature can be used for auto-locking or relocking routines. |
| ** Aux: Bipolar / Aux: Unipolar (2-position slider switch) ** | ** Aux: Bipolar / Aux: Unipolar (2-position slider switch) ** |
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| This 2-position slider switch is only accessible by removing the right side panel (see above) and sets whether the AUXILIARY OUTPUT SERVO is unipolar or bipolar. It is factory set to be bipolar so the auxiliary output can range from -12 V to +12 V. For some applications such as driving a PZT, limiting the voltage range to positive values is necessary. When this switch is in the unipolar mode, the auxiliary output ranges from -0.5 V to +12 V. Additionally, when in Ramp->Aux mode and Aux: Unipolar, the ramp is centered at ~3.5V instead of 0V. | This 2-position slider switch is only accessible by removing the right side panel (see above) and sets whether the AUXILIARY OUTPUT SERVO is unipolar or bipolar. It is factory set to be bipolar so the auxiliary output can range from -10 V to +10 V. For some applications such as driving a PZT, limiting the voltage range to positive values is necessary. When this switch is in the unipolar mode, the auxiliary output ranges from -0.5 V to +10 V. Additionally, when in Ramp->Aux mode and Aux: Unipolar, the ramp is centered at ~3.5V instead of 0V. |
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| **Ramp Master / Slave (Jumper)** | **Ramp Master / Slave (Jumper)** |
