Moderators: Dave Moll, Andrew Davie, Steve Anderson
gary wrote:> the problem of using higher laser levels without wiping the written raster lines from the laser glow
I assume the laser has a collimator?
harry dalek wrote:
An adjustable lens ?
The higher the laser level it is sort of similar to a CRT you can only make it so bright i need a contrast control but i know the glow from the laser being very bright causes a problem at higher laser levels this UV light is seen by other parts of the drum.
Well the spherical aberration you are seeing at high levels is always there, just not as noticeable because it is not as bright.
Yes I suppose a collimator is just a lens, but for good collimation it should not be of the common spherical kind - however I fear the correct (aspherical) kind to use would be outside your budget. The difference between the two can be quite remarkable (see image).
I think multi element lens collimators are better in this regard as well but probably even more expensive.
I was just asking really to make sure there was a collimator of any kind being used as obviously without one the situation would be even worse.
[/quote]This is way out of my knowledge and experience now but it may be well worth trolling (in the fishing sense) some of the laser communication sites as they would probably need good collimation.
I will have a google and see but i am sort of stuck with what i have got handy .PS: Come to think of it the laser in a laser printer must have good collimation I would have thought - perhaps that's worth looking at as a cheap source.
AncientBrit wrote:Harry,
Just an off the wall idea.
Are the colours from the laser and the drum fluorescence widely separated in wavelength?
If they are you might be able to insert a coloured filter in the viewing path only.
This would attenuate the direct laser feed but hopefully pass the output from the drum.
Kind regards,
Graham
]But isn't the problem that thegary wrote:But isn't the problem that the "over spray" from the laser dot is exciting the fluorescence of the previous lines?
gary wrote:Harry it's really hard to tell by video but I would swear that there is diffusion through the surface of the drum - if not then the mirror drum is spreading the light - what happens if you shine the laser directly on the drum?
aussie_bloke wrote:Great work Harry, awesome to see pictures on your mechanical SSTV, they are looking good!!!
Users browsing this forum: No registered users and 7 guests