h a l f b a k e r y"Bun is such a sad word, is it not?" -- Watt, "Waiting for Godot"
add, search, annotate, link, view, overview, recent, by name, random
news, help, about, links, report a problem
browse anonymously,
or get an account
and write.
register,
|
|
|
Please log in.
Before you can vote, you need to register.
Please log in or create an account.
|
After playing around with trying to get an ordinary bulb to
shine a reference grid, I realised a) the bulb was no where
near powerful enough and b) it was diffuse, causing the
blurring of bulb reference mask.
What if the bulb was placed in a parabolic reflective
container the only way out
is an area that all the
reflections have to be parallel to each other. Any rays not
exiting are reflected to have another go at the parabolic
mirror, if not reduced to heat. This of course, is what
happens at any torch head, except the bulb is usually in
the way and only half the generated light reflected
through the mirror.
To do this properly, the bulb has to be offset and out of the
way of the direct line of the parabolic exit. Think a reverse
mirror telescope with bulb at the eyepiece.
The thing is, there would still be rays slightly off the
perfect parallelism so what if there was a block of optic
fibres all perfectly parallel, sandwhiched together over
the exit. These optgic fibres would be different though,
the inner surface would not be about reflection but
absorption. The optic fibre sandwhich would only let
though the rays that are parallel to direction needed.
Summing up, a bulb enclosure to only let light of multi
frequencies, hence pseudo laser, in parallel lines for cheap
experimentation at home. The stronger the source the
better.
Did I say the beam was wide.
[link]
|
| |
collimated light =/= coherent light. |
|
| |
also, optical throughput is (solid angle)*(area) so as the beam
gets better collimated the amount of light going through it
gets less. |
|
| |
good effort but there are some science issues... |
|
| |
True, the width is only going to be big as the torch or
optic fibre block, but
compared to a laser's window, for home use, free and
portable. |
|
| |
The proof will be in the percentage loss between the
photons generated and those that manage to be reflected
in the case, straight out the optic fibres. Hopefully no
solid angle at all. |
|
| |
The masks or shadow puppetry should be sharp-ish at a
range of distances. |
|
| |
I think the sandwhiching is the key technology that needs to be explained. |
|
| |
When light comes out of a single optical fibre, it is not in the form of a collimated beam, it diverges and spreads from the end of the fiber. So unless the sandwhich runs from the lamp exit all the way to the target it won't do very much. |
|
| |
Or you could just have an infinitely bright point light source an infinite distance away, that would work pretty well I think and has the advantage of great simplicity. |
|
| |
another issue is that the optic fiber block (grid of small
circular openings) won't work as expected because of
diffraction...each small opening will cause the beam to
diffract/diverge outward. |
|
| |
1: You can get pretty tiny LEDs these days; use as a "point
source" with a parabolic mirror, et voila!
2: Why not just use a laser? |
|
| |
These optical fibers are special, with an internal
absorbing coating. Only photons travelling the length of
the fibre get through, almost parallel. |
|
| |
1 the led and supply lines are in field but yes, the optical
fibres will be an attempt at a grid of point sources. |
|
| |
2 I did think of a defraction grating but again either a
small area, one laser or changing distant between dots if
lensed
stack of lasers and defraction crystals? don't know. |
|
| |
what I was trying to realise was a standard flatish light
bulb that
put out a light grid that didn't change relative to the
distance away. |
|
| |
Increasing entropy is never a waste! It's the true purpose of the universe and everything in it, after all. |
|
| |
There can be purpose without consciousness |
|
| |
What you're describing is a standard bulb-in-a-box
microscopy light source, nothing new with that. Add on a
collimator & liquid light guide and that's the rig I have in the
next room. |
|
| |
//collimated light =/= coherent light// Exactly, coherent
light isn't needed anywhere as often as people think. Lasers
are used mostly because they're good at supplying an awful
lot of light a specific wavelength, you don't need coherence
for cutting steel for example. |
|
| |
The problem is the area needed. To coat the probable
play paths of a table tennis ball over a table, with the
light source above , needs multiple wide collimated
sources. |
|
| |
The masked, collimated light's shaddow pattern has to
interact with the pattern on the ball. |
|
| |