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Reconfigurable Laser Servo
Product Manuals - https://www.vescent.com/manuals/
Fig. 5: Schematic of the configuration transfer function and
user-controls.
The feedback loop is defined by the Gain vs Frequency plot shown above. ƒ
I
, ƒ
PI
and ƒ
D
define three
corners in the transfer function. ƒ
I
and ƒ
PI
are the frequencies where the first and second integrators
respectively switch from having integral gain to having proportional gain. ƒ
D
is the frequency where
the gain switches from proportional to differential. ƒ
I
, ƒ
PI
and ƒ
D
are controlled by two rotary switches,
where the upper switch is used to select higher frequencies, and the lower switch is used for selecting
the lower frequencies. The upper switch must be in the “low freq” position to engage the lower
switch.
NOTE: Adjusting the loop filter corners while locked may result in loss of lock. If this happens, unlock
laser before adjusting poles and corners and relock laser after adjustment.
NOTE: The triangle embedded in the rounded side of each click switch points to the selected value.
First Integrator (TOP)
Sets the frequency of the first integrator (ƒ
I
). This knob only selects higher-frequency positions (2 kHz -
200 kHz). To set ƒ
I
to lower frequencies, this knob must be placed in the LOW FREQ position.
First Integrator (BOTTOM)
Sets the frequency of the first integrator (ƒ
I
). This knob only selects the lower-frequency positions (10
Hz - 1 kHz) and is only active if the FIRST INTEGRATOR (TOP) knob is in the LOW FREQ position. To
turn off the integrator, this knob must be placed in the OFF position and the FIRST INTEGRATOR (TOP)
