My 445 build

yes thats all you need to knife edge.

you tell me if you need teleacopics? put a lens on the diode and measure the size of the beam at apeture. then work out the best way to knife edge two. then you can work out if the size of the beam is acceptable or not.

whats acceptable to one person might not be to another.

im not trying to be rude and unhelpful but use and apply logic to get an anwser then you can decide for your self if you like the anwser or not.

hope that helps

andy_con said:

yes thats all you need to knife edge.

you tell me if you need teleacopics? put a lens on the diode and measure the size of the beam at apeture. then work out the best way to knife edge two. then you can work out if the size of the beam is acceptable or not.

whats acceptable to one person might not be to another.

im not trying to be rude and unhelpful but use and apply logic to get an anwser then you can decide for your self if you like the anwser or not.

hope that helps

Click to expand...

Cool, will do. The beam size at the aperture is pretty large IMHO, it's an A140 in one of Dave's brass mounts with Axiz glass lens. I will measure the beam size tonight.

My DT30's are fitted with the smaller mirrors, 5x10x0.8mm so I am concerned the beam may be too large.

BTW, I recall reading somewhere a while back that the best way to measure beam width is with verniers and an LPM. Please the verniers across the beam and measure the vernier setting that results in 90% power and subtract the vernier width that results in 10% power. Does this sound correct?

Thanks for you responses to my questions.

i use whats known as a ruler the measure the beam size lol
there probably are more accurate ways but its fine for what i need.

measure the beam and then we can work out the best way or rotate abd knife edge the beams

Well measuring the beam width @ 1.2W is not easy! I gave up and instead fired the laser up for 10 seconds with a piece of pine sitting 1" from the lens. Measured burn mark is 3x1mm.

why would you try to measure the beam at full power?

turn the power down and try again

you cant measure a beam from burning marks

But the beam at full power is sometimes larger than the beam at low power.

Actually, measuring a beam profile by burn marks is (or was) a professionally used method.. Profilers of course have more detail, but a burn mark can tell you a lot..

These 445nm diodes do have very different beam characteristics when running low power than they do when being driven fully.. The beam at low power is almost single transverse mode, and it's also often single longitudinal mode as well up to about 50mW.

It looks like my response has already been made for me. It made sense at the time. And yes, when I dial down the power the beam shape is quite different.

i still disagree but ok.

surely when you burn something as it heats up the burn mark spreads out making the beam look bigger. but thats just my view

if your getting 1mm wide by 3mm high then you can simple knife edge two together for 2mm wide by 3mm high

andy_con said:

i still disagree but ok.

surely when you burn something as it heats up the burn mark spreads out making the beam look bigger. but thats just my view

if your getting 1mm wide by 3mm high then you can simple knife edge two together for 2mm wide by 3mm high

Click to expand...

Hence the quick test. I tried 5, 10, 15, 20 second burns, all gave the same result which is 1x3.

Thanks for you help.

just waiting on some drivers and mirrors then i can finish

Those are some big pics

grr at this forum...

So many people complain about image sizes, how do we have screen resolutions near 800x600 or lower??
Maybe I'm just spoiled, but I don't remember the last time I used a resolution lower than 1280x1024, and large images have never been a problem for me.

Now back OT.
:drool: Can't wait to see this one completed.
looks like a fun project. :beer:

hopefully it will be finished soon

mitbrown said:

So many people complain about image sizes, how do we have screen resolutions near 800x600 or lower??
Maybe I'm just spoiled, but I don't remember the last time I used a resolution lower than 1280x1024, and large images have never been a problem for me.

Click to expand...

Wow, you must work in Microsoft's GUI development department. They seem to have the idea in their head that graphics should scale to the size of the window. That way, no matter how high your resolution, no matter how many pixels you throw at Windows, you cannot take advantage of any greater information density. Look at their taskbar that can barely fit 10 or so tasks, or maybe just 15 on a vertical taskbar. Look at the overbulked Explorer windows, or just the framing for all their windows. It's like I'm using an OS made for old people and toddlers.

How does this relate to resizing your images? When you have a big image, it means I can only see one big image at a time on my screen. Not only that, that image contains no more useful data than a smaller image. Do I need to see the reflection of the room in the screw highlights? Do I need to see the amplified noise that your CCD sensor adds? Do I need to see the wood grain of your table? No I do not.

It's not a matter of screen resolution either. I'm running two 1920x1200 monitors here and I like to make the most of them by not needing to maximize or, god forbid, stretch the browser window across both monitors just to see the awesome beamshot you took on your 12MP camera, while still having to horizontally scroll. I didn't buy these monitors just to run one or two tasks fullscreen, and I shouldn't have to because someone is too lazy to resize his or her images down to reasonable levels.