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groups:mg:experiment:laser:285nmlaser [2015/08/14 13:27] – ssauergroups: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.
 +  * Laser-Diode current: 280 mA   @which settings?
 +  * Seed power (is displayed in the //FLPM RMU CCT 1.1.0.0// program): ~ 20 mW
  
-===== FLPM RMU CCT 1.1.0.0 =====+===== Turning on the Laser ===== 
 + * 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. 
 + * Start the program //FLPM RMU CCT 1.1.0.0// and select the checkbox of //Laser Enable//. 
 + * The //Power Setpoint//  **must stay** at //0.500 W// 
 + * Optimize fiber coupling to //Iodine Spectroscopy//. Transfer-efficiency > 70% 
 + * Change //Power Setpoint// for 285nm SHG operation 
 + * //2 - 2.500 W// for //100-150 mW// directly after 285 nm SHG. 
 + * 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 ===== 
 + * Unlock the laser in DigiLock 
 + * Now just turn off the main-power on the laser 
 + * Disable oxygen to 285nm SHG.
  
- * Laser Enable: push "on" +===== Locking to Iodine-Spectroscopy ===== 
- * Output Power: change "Power Setpoint"  +        * Start //DigiLock-Module Server// and connect to //S-MOT-Laser//  
- * 0.500 W for Iode spectroscopy fiber coupling +            * Push //Scan on// and //AutoLock// 
- * 2 - 2.500 W for 285 nm-SHG-Lock  +            * Change the //Offset Value// to 0 V 
- * Seedpower: ~ 20 mW +            * Change the frequency with the piezo on the toptica rack electronics to be close to the iodine resonance (check with wavemeter) 
-<note important> Edit any other values! </note>+            * Change the //Setpoint// (under //AutoLock//) to be in the middle of the error signal. Check, if the crosshair snaps to the slope. 
 +            * Move the crosshair to the second slope, rightclick on press //PID: Lock to Slop//.
  
-===== DigiLock-Module Server ===== 
- 
-        - S-MOT-Laser connected 
-        - start "DigiLock - SN 01265 - S-MOT-Laser": double click of S-MOT-Laser  
-            - push "Scan on" 
-            - push "AutoLock" 
-            - change the "Offset Value" to 0 V 
-            - change the "Setpoint" (under "AutoLock") of max slop of the middle peak 
-            - Push "PID: Lock to Slop" 
  
 +        * **Troubleshooting** 
 +            * If signal in DigiLock-Software does not update/ signal is frozen  -> click the sampling checkbar to activate
 +            * 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).{{ :groups:mg:experiment:laser:img-20210119-wa0001.jpg?400|}}
 ===== Lasersystem - Typical power values ===== ===== Lasersystem - Typical power values =====
- +The 285nm SHG was build by Jan Friebe and is described in his diplomathesis.
-The system was build by Jan Friebe and is described in his diplomathesis.+
  
 === 570 nm-Laser === === 570 nm-Laser ===
  
- * Outputpower after cube to 285 nm-SHG: ~ 1.2 W @ 2.5 W+ * Outputpower after cube to 285 nm-SHG: ~ 1.2 W @ 2.5 W 1140nm pump
  * Operationpower: < @ 3 W  * Operationpower: < @ 3 W
  * Max outpupower: ??? W @ ??? W  * Max outpupower: ??? W @ ??? W
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 === Iodine spectroscopy === === Iodine spectroscopy ===
  
- * For fiber: ~ 38 mW @ 0.500 W +== 500 mW pump of the yellow laser == 
 + * Infront fiber: ~ 38 mW
  * After fiber: ~ 29 mW @ 0.500 W (= 400 mV @ 0.500 W) [efficiency ~ 70 %]  * After fiber: ~ 29 mW @ 0.500 W (= 400 mV @ 0.500 W) [efficiency ~ 70 %]
  
- * For fiber: ~ 220 mW @ 2.500 W  +== Normal operation (2-3 W) == 
- * After fiber:  ~ 160 mW @ 2.500 W (= 2 V @ 2.500 W) [efficiency ~ 70 %]+ * After fiber: ~ 100 mW 
 + * At iodine cell: 20-40 mW
  
 ==== 285 nm-SHG ==== ==== 285 nm-SHG ====
 + * Outputpower: ~ **100+ mW** @ 2.000 W
 + * Stabilized power (infront AOM): **80-90 mW**
 + * Power behind the AOM: **43** mW @ 2.000 W (efficiency ~ 50 %)
  
- * Outputpower: ~ ... mW @ 2.000 W + * Power for the Zeaman-slower: **10 mW** 
- * Outputpower: ~ ... mW @ 2.500 W +
- * Power for photodiode after SHG: ~ ... mW  +
- * Stabilized power: **80 mW** +
- +
- * Power for the AOM in ... order: 67 mW +
- * Power behind the AOM: 37 mW @ 2.500 W (efficiency ~ 50 %) +
- +
- * Power for the Zeaman-slower: ... mW +
  
- * Power behind the mystical mirrow: ... mW + * Power behind the mystical mirrow: **30 mW**