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| d2:quick_start_opls [2016/07/13 21:40] – [D2-150 Alignment] Michael Radunsky | d2:quick_start_opls [2017/08/04 15:35] – [D2-135 Locking] Michael Radunsky |
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| The reflection point on the Error Signal is where the two lasers are at the same frequency. The Error Signal is a even function of offset frequency (Error(Δf) = Error(-Δf)), so there is a reflection point about Δf=0. The sharp slope to the left or right of the Δf=0 point is the lock point and can be adjusted by changing the VCO frequency. Which of the two lock points the laser will lock to will depend on the gain sign. Center the O-scope on one of the lock points and turn down the ramp amplitude. Flip the D2-135 Servo to Lock mode. If the Servo Output jumps to +/-10V, repeat with the opposite gain sign. At this point, you should have a lock that is holding the offset frequency to a specific value. You may be significantly broadening the laser because the servo is oscillating, but you have a basic lock. | The reflection point on the Error Signal is where the two lasers are at the same frequency. The Error Signal is an even function of offset frequency (Error(Δf) = Error(-Δf)), so there is a reflection point about Δf=0. The sharp slope to the left or right of the Δf=0 point is the lock point and can be adjusted by changing the VCO frequency. Which of the two lock points the laser will lock to will depend on the gain sign. Center the O-scope on one of the lock points and turn down the ramp amplitude. Flip the D2-135 Servo to Lock mode. If the Servo Output jumps to +/-10V, repeat with the opposite gain sign. At this point, you should have a lock that is holding the offset frequency to a specific value. You may be significantly broadening the laser because the servo is oscillating, but you have a basic lock. |
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| === Optimizing the Lock === | === Optimizing the Lock === |
