How to achieve the finest laser line possible with the least spread in the opposite..

[planters]

Regarding the cylinder, use a plano/convex if the output is parallel. As I posted above, I would avoid the cylinders alltogether. Your concern should now be about the telescope and the rules/permissions.

[Laser57]

Although I am buying equipment and asking questions, this is far too early of a stage for asking, I might not even pull this together. Even if denied, I have another use for the gear or I wouldn't be buying it, so either way it goes, I'm good

Projects like this take me a long time, I've already been thinking about it for a few years. I could ask now and be approved, when ready be denied. Took me 5 years to finish building a earth-moon-earth array of antennas to use the moon as a passive satellite to hear my own echo's at 144 MHz, but I built it and had a signal to noise ratio of over 10 dB on the returned echo's. Helped to have 4.5 megawatts of EIRP. The reason it took so long was the cost as well as having to buy a large plot of land to set the thing up on, it was a monster. This project is fairly small in comparison so should come together quicker, but still could be a couple of years out, if later approved.

A+++ thanks!

Edit: You might find this short video clip interesting

The ESA took some video from the ground of the ISS as they illuminated it with a 3.6W 532nm laser. Pretty cool stuff and an amazing video. They must have used some mighty fine adaptive optics to get images like that which would normally be impossible due to seeing limitations. Or it is possible that they used very high speed photography with a fast optical tube and then made the video using some kind of speckle imaging composite post processing technique.

[Laser57]

Please excuse the double posting, although a different question:

This is in regard to power density ratings for a AR coated lens;

If a lens has a power density limit of 500MW/cm2, I'm calculating up to about 15 watts of CW power can be used with such a lens without damage to the AR coating when the beam diameter is 2mm. From practical experience, can someone comment whether that kind of power into a AR coated lens with a 2mm diameter beam is common?

Thanks

[planters]

Good quality glass lenses with AR coatings should never be a limit to the energies you will commonly encounter. 500W/cm2 is a very low rating (500,000,W/cm2 is more typical) , but your calculation is correct. Most damage occurs with high peak power pulsed lasers or when an otherwise good lens gets dirty. With dirt, all bets are off. Here, even low power lasers can heat the dirt which damages the coating/lens.

[Laser57]

From what I've been able to find, it's 500 megawatt/cm2, the MW in caps means mega, is that even possible? That's how Special Optics shows it on their web site, as MW. OK, I will keep it clean, thank you for the advice and comments.

[Laser57]

Update: I had a small low divergence laser pointer host built for me by Ehgemus which uses a G2 lens on a Aixiz module which is de-focused to produce a spot on a 2 inch diameter PCX lens at its focal length away from the G2, this creates a beam expander using just the de-focused G2 and PCX lens together. After that I shot the expanded beam focused to infinity into a pair of line cylinder lenses which are mounted in a black tube on the end of the host, as seen in the photo, below. This can be used for emergency signalling of aircraft in Alaska, which is legal, many pilots carry a small version of this pointer in their emergency packs but they are not nearly as effective as this one will be with a several hundred milliwatt output laser diode in it along with extremely low divergence. I imagine the flash can be brightly viewed from 100 miles away, if you had a line of sight path that far for high flying aircraft (not for close in flashing of aircraft, use the cheap little commercially built one for that). The uber long range is due to the extremely low divergence of the line thickness, since the beam was expanded prior to going through the cylinder lens the low divergence properties are transferred to the line, thanks everyone for your help with this idea, although not the huge 6 inch diameter one I want to someday build, I'm still collecting parts for that one.

[kecked]

NASA uses lasers to communicate between satellites all day long and they use fiber lasers in the 1-5W range. Pretty much anything you can aim they can detect. They are planning to use this to communicate to the planets so figure the SNR they can see! Those lasers are however IR.

http://www.space.com/23308-nasa-moon...ns-record.html

I saw this in person and the rig fits on a desk.