Newbie- laser controller

[ne_bun]

Hello

I need an direction on this perspective of understanding..so
You have an laser and an XY table, the table was been controlled by an controller, then the software to make the movement. The head of the machine will move the laser (or laser head). but how to control the laser? for on-off and how can the power to be reduced for different operations?

thank you

[Tweakie]

What type and power of laser are you considering ?

Tweakie.

[bpoulin]

Generally the laser is turned on and off as it makes a pass, kind of like a printer. With the Lasercut software you do things in layers, one layer is one speed and power, and if you want a different effect you do that using another layer with a different speed or power.

[ne_bun]

thank you for the answers.

for example an laser with 100 Watt power (CO2). It is working like an printer (jet, not laser printer) and wen the color of the pen is red then the power of the laser is less (example).. but wen you reduce the power of the laser what you are reducing? electrical power, the gas that will be inside (or the gas is closed)?

[Tweakie]

Originally Posted by ne_bun thank you for the answers. for example an laser with 100 Watt power (CO2). It is working like an printer (jet, not laser printer) and wen the color of the pen is red then the power of the laser is less (example).. but wen you reduce the power of the laser what you are reducing? electrical power, the gas that will be inside (or the gas is closed)?

When you reduce the power the energy through the tube or lasing medium is reduced therby exciting less electrons and causing the emmission of less photons (if you can call them that).
The methods commonly used are (a) reducing the current flow through the medium (PWM) or (b) reducing the duty cycle (PRF) or a combination of both.

Tweakie.

[ne_bun]

Tweakie, thanks for the answer. I like to move over. What will be the name of the device (principle) witch control an power supply via an software (in this case, an large volts and less amperes [or not?])?

[Tweakie]

For my DC excited laser I use a power supply like this one http://www.cooperman.talktalk.net/PSU.pdf
The power output of the tube can be controlled from software by applying a 5 Volts Pulse Width Modulated (PWM) signal (between 0% and 100%) generated by the software and applied to the power supply.
Alternately a 0V to 5V dc (using a multiturn potentiometer) can be applied to set the maximum power output of the tube and the actual power output controlled by varying the duty cycle (Pulse Repetition Frequency) of the trigger input under software control. This is the method which I prefer to use.
I am currently developing (slowly, as time permits) a controller for my RF excited laser which uses PWM control but also has the ability to vary the PRF. *RF Laser

Hope this helps.

Tweakie.

[geekinesis]

So by using the second method you are literally switching the beam on and off very fast? How fast?

The pwm method just keeps the beam on but reduces the current.?

I still need to get my head around this as well. Can either method damage the power or tube in any way?

[Tweakie]

Hi Guys,

I am not the expert here and you really need to read some of the laser manufacturers manuals to get a better feel for the methods they use but basically.........
The maximum pulse repitition frequency recommended by Synrad for the PWM signal (0%=off : 95%=CW mode) is 20kHz and the average, optimum performance is achieved with a PRF of 5kHz. Some manufacturers controllers go down to 500Hz - the interesting thing here is that although you can achieve the same power density by various combinations of PWM / PRF the effect on the work is different, which is the reason for allowing this adjustment or variation.

Tweakie.

[ne_bun]

Tweakie, for me you are looking like some one, how knows really good about lasers. I am looking to your page. Very nice! Congratulations. After clearing my head a bit, maybe, I will put again stupid questions.