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| groups:mg:experiment:laser:285nmlaser [2016/04/20 15:55] – klaus | groups:mg:experiment:laser:285nmlaser [2022/04/06 05:51] (current) – [Locking to Iodine-Spectroscopy] wfriesen | ||
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| ====== 285 nm-Laser (S-MOT) ====== | ====== 285 nm-Laser (S-MOT) ====== | ||
| The 285 nm Laser consists of a two-stage frequency doubled, raman-fiber-amplifier MOPA. The raman-fiber-amplifier is seeded by a diode laser. | The 285 nm Laser consists of a two-stage frequency doubled, raman-fiber-amplifier MOPA. The raman-fiber-amplifier is seeded by a diode laser. | ||
| - | * Laser-Diode current: 280 mA | + | * Laser-Diode current: 280 mA @which settings? |
| * Seed power (is displayed in the //FLPM RMU CCT 1.1.0.0// program): ~ 20 mW | * Seed power (is displayed in the //FLPM RMU CCT 1.1.0.0// program): ~ 20 mW | ||
| ===== Turning on the Laser ===== | ===== Turning on the Laser ===== | ||
| - | * Enable oxygen to 285nm SHG. | ||
| * Enable main-switch. Now set the key to standby. | * Enable main-switch. Now set the key to standby. | ||
| * Wait for the LED to change the color from orange to green to orange (~15 seconds after turning on). Turn the key now. | * Wait for the LED to change the color from orange to green to orange (~15 seconds after turning on). Turn the key now. | ||
| Line 14: | Line 13: | ||
| * //2 - 2.500 W// for //100-150 mW// directly after 285 nm SHG. | * //2 - 2.500 W// for //100-150 mW// directly after 285 nm SHG. | ||
| * Do not exceed much more than //3.5 W// | * Do not exceed much more than //3.5 W// | ||
| + | * Flush the SHG with oxygen, by opening the bypass for roughly 10 seconds. | ||
| + | * Scan the SHG and optimize the incoupling and crystal position | ||
| + | * Lock the SHG, the voltmeter should display a value around 115 mV (@ 2 W Power Setpoint) | ||
| + | * Activate the powerstabilization | ||
| ===== Turning off the Laser ===== | ===== Turning off the Laser ===== | ||
| * Unlock the laser in DigiLock | * Unlock the laser in DigiLock | ||
| Line 28: | Line 30: | ||
| * Move the crosshair to the second slope, rightclick on press //PID: Lock to Slop//. | * Move the crosshair to the second slope, rightclick on press //PID: Lock to Slop//. | ||
| + | |||
| + | * **Troubleshooting** | ||
| + | * If signal in DigiLock-Software does not update/ signal is frozen | ||
| + | * If signal in DigiLock-Software does not show the usual error-signal at correct frequency, but is saturated at left and right edge of the frame (see picture) -> Check the ref input for the lock-in-amplifier (near the iodine spectroscopy). Probably the input signal is too low. It should be slightly higher than 2 V (~2.2V works fine).{{ : | ||
| ===== Lasersystem - Typical power values ===== | ===== Lasersystem - Typical power values ===== | ||
| The 285nm SHG was build by Jan Friebe and is described in his diplomathesis. | The 285nm SHG was build by Jan Friebe and is described in his diplomathesis. | ||