wklaser wrote:PWM is for RF laser tube spec
and if for glass tube,this is useless
I am not sure where you got this information, but I believe you may be confusing PWM with the laser's trigger frequency. RFs use specific frequencies, but glass tubes do not.
PWM (input) is the method that ALL current laser PS use to set the power level of the output. It ranges in % from 0 to 100. It is a 5v (usually 3.3v acceptable) DC signal that is modulated by turning it on and off so that it is on a certain % of the time. The PW then, receiving such signal, drives the laser tube to the corresponding % of power. (Not linear as most PS and tube combinations vary, but close enough for this discussion.) Nearly all modern controllers use PWM to control the power, regardless of whether using RF or Glass tubes.
If you are using a modern controller (DSP, etc), then the PWM signal is provided automatically. If you are building your own controller, then you can use an analog to pwm circuit (Hobard Designs in Australia is one that comes to mind).
All modern laser PS also accept an analog (0-5v) signal.
Tell us what the original poster really wants to do and how this question came up and we will be happy to help them figure it out.
Here is an article I posted about PWM and laser output. It does not deal with the electronics part but give you a base for understanding what it does and how your laser reacts to it.