suggestions for qcw infra red pistol?

[drspastic]

hi, im new to playing with high power lasers, in fact i only recently found out laser tech has got tthis far.
i just bought a 200mw green and 1000mw blue and the first thing i noticed exept for the power is that the dot shape and collimation on the green is far better (true dot) than the blue (rectangle).
now i assume this to be because the green is dpss and therefore not dependent on the shape of the semiconductor block, but the secondary lasing crystal.

now i want to build a target pistol to burn holes in card targets for use similar to a bb gun. the power i estimate i need to do this is a 10w 0.1 second pulse to do the same joule damage as 1w for 1 second.
i also want it infrared so no visible beam.

now this presents a few questions: at a 10m range using a infrared diode, will dot size and collimation be possible to the degree i will need or will i need to use dpss to get that. if so, am i best starting with a green unit and removing the frequency doubler?
other alternative is use an infrared diode and add my own ss laser to it, which i assume requires a lot of allignment.

next question: as a seasoned electronics engineer, i understand most semiconductors as handling very high pulse powers for very short times. does this equate the same with laser diodes?
can i pump 10w for 100ms from a 1w cw diode? or do i need a 10w diode and downscale the psu and heatsink to the duty cycle expected. will a diode need more warm up time than it will get in the 100ms pulse? if so, do i force it using a shaped pulse?

i really dont want to get into q switching or gas lasers as the unit should be no bigger and heavier than a nice old 1911 including battery to give 50 shots or more.

any thoughts? (i know the safety issues, so just tech please)

 

[LSRFAQ]

10 watts in a tenth CW will not do what you want to do. I'm a professional Field Service Engineer on high power, pulsed lasers. We do "mode burns" on a coated paper card to tune and align the lasers. You need half nanosecond, very high peak power pulses to do as you wish at those "low" power levels. Which are not so low...

I know you don't want to hear this, but :

The problem with this scheme is the eye hazard. Which I assure You. You have no clue about. The NOHD is on the order of several hundred yards, and the backscatter is quite hazardous, even at 10-20 feet. You end up needing a similar level of range safety to a .22 rifle.

I hate laser safety glasses, I try to design systems so I don't need them. However when I work on these pulses, I wear them and visually check the ratings twice. Its very clear what happens to your eye should you miss or get a back reflection. You'd hear a loud pop and feel the shockwave in your head if you messed up. Right before the eye possibly fills with blood. I've been working with lasers for 20 years, and I'm terrified of one of these.

I know exactly how much power you need. Exactly what density of energy you need at the paper. It's not something you do with a surplus laser diode, either. Even a big 40 amp one.

Gas won't do it, and neither will a diode assembly that fits in your hand. To get the power down to managable levels, you need a very fast Qswitch, and not a acousto-optic one.

Unless you have VERY high peak power, it takes 100-250 milliseconds for the paper to even start to discolor. Card stock has some inorganic additives that slow down the process greatly.

We have highly optimized, custom made, paper for laser quality control. Because the off the shelf stuff usually gets a hole in it before it discolors. Ironically I can't disclose whats in the coating, as my boss spent a lot of money developing it. The commercial lasermode burn paper is not so reliable.

OD7 and full wrap-around, pulse rated, safety glasses before you even try.

I'd joke about them paying me to burn stuff, however if/when the dust from a mode burn gets on the optics, we can lose a customer. We enclose the paper target in a plastic bag. If I don't, the next shot burns the optic where the dust has landed.

We use paper because it takes a 10,000 dollar ICCD to see the quick pulses. On a normal CCd they are quite blured.






Steve

 

[mhemling33]

^^^^^ this guy has no idea what he is talking about! lol :beer: i am jk by the way!