7.2.3 Synchronizing with a Free-Running Laser |
Normally, the SP-ICE-3 Card requests a laser pulse by asserting the LM signal, and assumes that an optical pulse will be delivered after a constant and predictable delay.
For lasers which comply with this assumption, the card can easily control when and where marking will take place, and the laser pulses will be output at the desired scanner positions.
Free-running lasers, however, do not output a pulse after a fixed delay, but after a delay that lies somewhere in the range 0 to (typically) the inverse of the pulse repetition rate.
Without any further compensation, this variability has an adverse effect on the desired marking position, and results in a worst-case positional error proportional to the product of the mark speed and the maximum pulse-delivery delay.
The SP-ICE-3 Card's synchronisation feature can provide suitable compensation.
Laser Hardware RequirementFor the synchronisation feature to be effective, the laser must provide an output signal which becomes active when it delivers an optical pulse.
This signal may be connected to any SP-ICE-3 Card input that supports, and has assigned to it, the Triggered function.
For example: Port “Laser Interface In”, input “Din.1”, function 2.
Please refer to 7.2.1 Laser Configuration Procedure.
Synchronisation FeatureWhen LaserConfigEnableLaserSync is set true, the SP-ICE-3 Card will enable synchronization with a free-running laser.
The feature employs a compensation algorithm that measures the delay between the expected delivery time of the pulse, as requested by LM, and the laser’s actual delivery time, as indicated by the Triggered signal.
The measured delay is multiplied with the mark speed, and the resulting distance is applied as an offset to the current scanner position.