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d2:laser_servo [2019/09/06 17:35] – [Right Side Panel] Michael Radunsky | d2:laser_servo [2020/03/16 22:21] – [Description] 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. |
<WRAP center round box 400px> | <WRAP center round box 400px> |
| **C** | **B** | **A** | ** Hold Time** | **N+1 Relock Time** | | | **C** | **B** | **A** | ** Hold Time** | **N+1 Relock Time** | |
|0ff|0ff|0ff| 60 µs | 150 µs | | |Off|Off|Off| 60 µs | 150 µs | |
|0ff|0ff|0n| 125µs | 300 µs | | |Off|Off|On| 125µs | 300 µs | |
|0ff|On|0ff| 250 µs | 600 µs | | |Off|On|Off| 250 µs | 600 µs | |
|0ff|0n|0n| 500 µs | 1.25 ms | | |Off|On|On| 500 µs | 1.25 ms | |
|0n|0ff|0ff| 1 ms | 2.5 ms | | |On|Off|Off| 1 ms | 2.5 ms | |
|0n|0ff|0n| 2 ms | 5 ms | | |On|Off|On| 2 ms | 5 ms | |
|0n|On|0ff| 4 ms | 10 ms | | |On|On|Off| 4 ms | 10 ms | |
|0n|0n|0n| 8 ms | 20 ms | | |On|On|On| 8 ms | 20 ms | |
</WRAP> | </WRAP> |
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