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c4r0

Sat Oct 03 2009, 08:14AM

Registered Member #151 Joined: Sun Feb 12 2006, 02:53PM
Location: Poland
Posts: 153

The beams are not wisible at all without smoke. There's a lot of smoke from burning rosin with soldering iron

This is the only kind of smoke I have but seems to do it's job pretty well. In closed room, about 3x4 meters, this smoke remains quite long and beams are perfectly visible. The power of this laser is about 50mW total so it's really weak.

...

Sat Oct 03 2009, 08:52AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

It depends on the power, over about 100mw is quite visible in air without smoke, with a nice layer of fog even 5mw will show up nicely in a dark room.

@Cr40 - Sorry you missed my poster, I actually haven't seen any proof that the poster ever got put up (and the professor who graded it doesn't recognize me

) but the system is working pretty well. I put my new dicro material in it and the power is up to a solid 100mw or so of white light, unfortunately my camera is completely blind to 405nm so its hard to get good pictures of the system, so here is one taken with my cell phone, and one of the whole projector

The offer on the dicros still stands, I cut some pieces ~5mm square of the reflect 532 and reflect 405, unfortunately the reflect red dicro had terrible performance (didn't reflect much red), so I am using a mirror salvaged from a DVD drive currently, and using the red diode as the first in the series (so the poor transmission characteristics of the DVD-rom dichro don't' have much of an effect). But if that is ok with you, I can send you the set of 3, although getting it shipped to Poland might end up costing an arm and a leg

c4r0

Sun Oct 04 2009, 04:19PM

Registered Member #151 Joined: Sun Feb 12 2006, 02:53PM
Location: Poland
Posts: 153

Hey, I'm on hackaday

cool

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Sun Oct 04 2009, 06:20PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Quite nice! I was considering submitting mine, although in my sites current state I am not sure how well it would handle a hackaday-ing (lots of big images on a 2mbit up pipe)

One tip to help reduce the issue that some cameras are not sensitive to 405nm is to project on fluorescing target (like a blank poster board) so that your camera can detect the much more ccd friendly ~460nm light.

wylie

Tue Oct 06 2009, 07:04PM

Registered Member #882 Joined: Sat Jul 07 2007, 04:32AM
Location:
Posts: 103

... and c4r0:

Too Cool. Just Amazing. Both setups are absolutely beautiful.

I got the idea for my laser-plotting project from hackaday, but it was your two projects that got me to actually make it happen. Kudos, Grats, and Highfives for the both of you.

and the professor who graded it doesn't recognize me

That's sad. Did he even look at the project, or do they just rubber stamp their grades? Seriously, was there a cooler project anywhere on campus that year? Unless you had classmates working on breakeven-capable fusion reactors, or maybe commercially viable spacecraft....

So, either of you thinking about a next step? How about a new deflection system which would allow you to scan fast enough for raster display. I'm not sure what could provide enough deflection at the speeds required though.

lpfthings

Wed Oct 07 2009, 08:58AM

Registered Member #1361 Joined: Thu Feb 28 2008, 10:57AM
Location: Cairns, Australia
Posts: 305

wylie wrote ...

How about a new deflection system which would allow you to scan fast enough for raster display. I'm not sure what could provide enough deflection at the speeds required though.

I have also been thinking about this, the best way I see would be to use 2 small hexagonal mirrors mounted on fast-ish motors, they would give you a XY field, then you just have to modulate the lasers fast enough. THe problem is, you would have to modulate the lasers a lot faster than the little green module can handle. It is DPSS, and the conversion process isn't as fast as diodes, so you would have to use a green laser with TEC cooling on both crystals to get fast enough modulation without jellybeaning (Term used when the laser doesn't have time to turn on and stabilize before it's switched off again).

...

Wed Oct 07 2009, 06:29PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

I did think about it for a little while, I would probably use an external modulator for the green, a polygonal mirror for the fast axis and a scanner of some sort for the slow axis (to avoid needing to sync up two polygonal mirrors). The issue with raster scanning is that you really do not have a lot of power to play with, a 'real' projector will have 10-1000w of light power to start with, so with a laser that has perhaps .1w you really have a lot going against you. The real benefit to using a vector scanner system is that you can make the best use of the limited power you have available, so you can get nice bright outlines with a small amount of power.

As to my project, there were TAs that watched our presentations, the professor was supposed to come but noted that he has a family who is more important to him than us

My project was probably one of the more interesting of the bunch, mainly because I knew what I was doing, had already finished the laser head before starting, and was willing to spend time working on it. The next runner up was probably the person who took a clock face and replaced the times with the dining commons on campus, then used a ton of processing to scrape the menus provided by the dining commons and a list of his favorite foods to point to the dining commons that he should go to

In the mean time, I am working on a higher power laser, it all goes well I should be able to get 100w of IR laser power

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