I'm a student, very new to this, and need help. Want to build my first scanner.

[Bradfo69]

Green or, most commonly 532nm is the most visable to the human eye. There is a bell curve that I'll try to find a link to that demonstrates it but, When trying to compare equal brightness, it takes considerably more power in either red or blue to match the brightness of green. This isn't exact but just for illustrative purpose, say you've got 500 mW of 532. In order to get 445nM (a common and inexpensive source of blue) to look equally as bright, you might need 2.5 watts. Same with red, if you want 650nm to look as bright to the eye, you might need 4 watts. So, for high visibility, your best bet is the green. To look the brightest on a building at a distance, green is simply the most bang for the buck. Due to the recent surge in cheap 445 blue diodes though, you can homebrew a very high powered blue that will look as bright as the green but will still need to be multiwatt. And, with techniques such as knife edging and buying necessary optics, to get that much blue in the first place, you may be better off with green.

Yes, you may use the Etherdream DAC with the REKE or, any other form of DAC that utilizes the 25 pin ILDA standard connection. Getting an analog green versus a TTL green should be a minimal increase in price. Again, a not exact example would be $800 for a 1 watt TTL green versus $840 for analog. The price difference is usually minimal.

edit: j4cbo beat me to it as I was typing my response.

[dnar]

@dsl_jon

Your a star, a legend and a bloody nice guy!

@echelon

Nice opening post, quite refreshing. Good luck with your project!

[BIRDMAN]

Hello echelon, I have a american 60X argon and some other stuff that you might be interested in. I haven't thought about pricing it. It probably would be very affordable for you . I have toted this stuff around a while. Argon is 100mW scanner is 12K I think. Software is Amaga based With a emmulation program for PC. If you have an interest please PM me.
BIRDMAN

[echelon]

Sorry I've been gone awhile! I was traveling with family and helping out with things.

I want to thank Jon and j4cbo and everyone in the IRC channel for being so much help with this. And everyone who has posted on this thread as well.

Since I'm worried I'll run out of summertime to write code and don't want to waste my efforts with building a scanner (electronics are not my forte; I do want to build one later though!), is there anyone that might be willing to build something to my specs? If you can show me some of your work and give me an estimate, I can pay upfront via PayPal.

The reason I'm asking is because the Reke probably doesn't have galvos good enough to project a game of Pong or Tetris onto a 2-story dorm building. I can definitely rule out demos with the Canny or Sobel edge detection algorithms, too. I just want to concentrate on coding, and early optimization is painful and slows learning.

I don't care about multiple colors, just a single dimmable bright green would be fine (since it's cheap and highly visible). Visibility at dusk/night is required, but moderate visibility during the day would be very welcome as well.

To summarize the project requirements:

• Green laser with high visibility
• Moderately high to high KPPS
• Moderately high to high scan angle
• Support for ILDA so I can use EtherDream DAC
• Rugged case so I can drag it around campus / loan it to my dept. for use without being nervous about it getting messed up.
• Can project onto building

If it breaks down, then I might be getting into the electronics. I suppose an accessible case that allows me to mess with (or upgrade) the components in the future might be a nice addition (but is not required).

Sorry that I keep bumping this post! You've all been so much help, and I really appreciate it. If anyone wants to contact me directly and in private, PM me or email me. I'll also hang out in #PL from time to time as well as j4cbo's #etherdream on FreeNode.

Thanks everyone!

Edit: BIRDMAN, sorry I missed your message. I'll PM you shortly. I'm not sure I know what that technology is, but I'll ask / investigate.

[james]

Since you only want one color, green might not be the most economical choice of laser if you want something that is really bright and analog modulated.

You might want to look at the 445nM blue diodes for that.

But you will find a limit to their power compared to DPSS green.

It's all a matter of how much you want to pay for one color.

James.

[masterpj]

PL user masterpj tried that at the most recent DutchLEM. I'd say the technique works, but it's hard to set it up. You need to make sure the images overlap each other perfectly and you need to apply geometric correction.

Actually its not hard to set up, especially if you lay one projector on top of the other or at least place them close.
Though the first option is the fastest (which only is possible if you can either lay the projector on a flat surface or have a truss where u can have the second projector hanging above (2 ends on the truss top and bottom)

It really depends how you position the projectors, it will be a problem if you place the projectors too far, there is only so much correction you can do.
Though im working on something myself to get rid of that.

[djpsych]

is there anyone that might be willing to build something to my specs? If you can show me some of your work and give me an estimate, I can pay upfront via PayPal.

Sent you a PM on a project you might be interested in

[echelon]

Thanks so much. I just emailed you.

[norty303]

Since you only want one color, green might not be the most economical choice of laser if you want something that is really bright and analog modulated.

You might want to look at the 445nM blue diodes for that.

I would think on a bang for buck basis on visibility, cheap DPSS 532nm heads still have it.

by the time you've bought a diode, lens, mount, driver etc for your cheap 445 diode, you could've got maybe 200mW of 532.

[simonb]

Hi,

I am also looking into self building a laser module. Mine will be a 445nm blue laser. But I also require a continuous 100% duty cycle. I am advised that the driver as well as the laser diode would require cooling.

the best advice was found in the 445 forum, & also the many helpful replies I received on my post at:-

http://www.photonlexicon.com/forums/...-lasershow-use .

It was suggested that I use the FlexMod P3 as my driver as it is easier to heatsink than some of the smaller driver circuits. I can either use a standard Aixiz module, which is a cylindrical tube that contains the laser diode & has an adjustable focus lens at the end. This could be mounted into either a brass mount, or one of the following special housings.

One suggestion was the housing/heatsink at:

http://www.innovam.com/en/produit_en...ier_en=HS-12en . And

http://www.greenlasermodules.com/Z-B...essories.html#

There is also a specially drilled PC Processor type heatsink/fan available. This is drilled/reamed to 12mm to accept my Aixiz module. I will post details once I manage to find them!

Also you mentioned combining R, G & B lasers to make white. There is a useful doc on Laser f/x that describes that because our eyes perceive different colour light at differing non-linear intensity, you need an almost golden ratio of Red to Green to Blue in the proportion 4.6:1, 1:1 & 2.6:1 to achieve white. The page in question is http://www.laserfx.com/Backstage.Las...Archives4.html .

Finally Cloud Writing. There was a large 20W argon laser installation in the Spainish coastal resort of Llorett-de-Mar. It was a Coherent i20 water-cooled Argon plasma tube, with the normal XY galvos. At the time (1988) I worked as a Field Service Engineer on this nightclub rooftop installation.

It was meant to write laser graphics & text onto other buildings & cloud. But it really did not work if the clouds were too loose/misty. Only the tight fluffy ones worked. But the main problem was that you could only see the effect at a certain angle. You had to be literally behind the laser projector. Any angle off to either side & all you could see was a greenie blue blur!

It was strange that the danger to aviation that a huge 20W laser presented was never really investigated, but this was the 80s! Still, the Nominal Hazzardous Distance of such a laser could have been such that aircraft flying nearby were in danger, not to mention that Barcelona Airport was not far!

I hope you achieve your aim, & have a lot of fun learning along the way! This is a great community, with some very knowledgable people who are always willing to help. Even with matters such as using a Multi-channel sound card as a DAC!

Ta,

Simon B.