====== 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

===== 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.

===== Locking to Iodine-Spectroscopy =====
        * Start //DigiLock-Module Server// and connect to //S-MOT-Laser// 
            * Push //Scan on// and //AutoLock//
            * Change the //Offset Value// to 0 V
            * Change the frequency with the piezo on the toptica rack electronics to be close to the iodine resonance (check with wavemeter)
            * 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//.


        * **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 =====
The 285nm SHG was build by Jan Friebe and is described in his diplomathesis.

=== 570 nm-Laser ===

	* Outputpower after cube to 285 nm-SHG: ~ 1.2 W @ 2.5 W 1140nm pump
	* Operationpower: < @ 3 W
	* Max outpupower: ??? W @ ??? W

=== Iodine spectroscopy ===

== 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 %]

== Normal operation (2-3 W) ==
	* After fiber: ~ 100 mW
	* At iodine cell: 20-40 mW

==== 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 %)

	* Power for the Zeaman-slower: **10 mW** 

	* Power behind the mystical mirrow: **30 mW**