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Submitted by Galil_DJR on Mon, 07/13/2009 - 13:48

Galil Laser Control options focus around a group of specific application requirements found primarily in laser marking, inscribing, raster imaging, and intensity control.  Although lasers are particularly suited to these modes, many other technologies are applicable, including focused ultrasound, imaging and high speed inspection, and plasma and water cutting.

The typical mechanics configuration for a Laser Control application is a two or three axis stage actuating a laser rail.  The control signal for a laser application is typically a PWM (Pulse Width Modulated) digital signal at a particular frequency and duty cycle (see Figure 1)

50% Pulse Width Modulated signal with increasing frequency

Figure 1 A 50% duty cycle PWM with an increasing frequency

Controlling the characteristics of this control signal can affect the operation of the emitted beam in various ways (see Table 1).

Table 1 Laser Control
Beam Characteristic Description of Modification Effect
PWM Duty Cycle The on-time of the signal can be modified from 0 to 100 % The on-time can effect the mark radius and line thickness of a beam's result
Pulse Frequency Vary the frequency of the PWM The intensity of a laser can often be controlled with frequency.  This allows for various grayscale or even color imagery, and control of depth of cut.

Galil motion controllers can provide precision generation of the laser control signal.  Hardware acceleration and firmware integration provide high performance motion control that is accessible to the standard motion features of the Galil command set.

Once dynamic modification of laser characteristics is possible, a whole new world of options is opened up allowing for very sophisticated motion control.  The Galil pulse-on-position, also called output compare (See OC in the Command Reference), provides a super-accurate, hardware-based position synchronization for lasing the substrate at an exact position.  A laser imaging application might use PWM and Frequency control in concert with pulse-on-position to form a pixel-based raster image (see Figure 2).

Figure 2 The pixels of the Galil logo have exact horizontal and vertical centers as a result of Galil's output compare.   The pixel radius is controlled by the PWM duty cycle of the laser control signal when it is pulsed.  The differences of pixel radii provide for the effect of image brightness.

To provide for the fastest possible performance, the stage must be moving at as fast a speed as mechanically possible.  This can be accomplished by providing a hardware-based pixel queue, or FIFO (First In, First Out).  Similar to a raster image processor (RIP) found in laser printers, an image can be transferred into pixels, with the requisite information including physical location of pulse, PWM duty cycle, and even PWM frequency.  This serves as a laser "bitmap" that can be queued and dequeued quickly from hardware to allow for even the fastest motions.

There are many, many more features available in Laser Control Options offered by Galil.  To discuss the options available for you application, including the details above, precise active-window control, vector speed synchronization, and more, contact Galil's Applications Department today.