Minimizing inter-photon distance in a non-coherent light interfer. experiment-

[ndvcx]

A 500 meter dark tunnel with 1000's of strong flashlights mounted on all sides pointing toward the center, not length, of the tunnel. At one end of the tunnel is a single flashlight, horizontally mounted, at the other is a 2 meter "dark" section w.o. flashlights, and a narrowed opening so the observer can only see the single, horizontal flashlight pointed at him/her, 500 meters away. There is a perfect vacuum in the tunnel. All flashlights are the same type, power and color.

What is the outcome here as you look down the tunnel. Non-coherent light cannot be interfered by other light. Will it look the same with the "interfering" flashlights on and off ?

Comments appreciated..(For me, if photons have any mass at all, it is hard to accept that none of the 1000's of interfering flashlights would not knock some photons out of their path on the way to the observer. )

 

[cragar]

Photons have no mass , But the light can interfere, the flash light 500m away from you , the intensity from that bulb will fall off as 1/r^2

 

[okirfan]

Any body knows about how to align OFF AXIS PARABOLIC MIRRORS?

Please reply

 

[Andy Resnick]

Any body knows about how to align OFF AXIS PARABOLIC MIRRORS?

Please reply

Aligning an off-axis mirror is extremely difficult for three main reasons: 1) the surface is non-symmetric, 2) the optical axis is not present, and 3), adjustments are non-orthogonal.

Because of this, there are several methods that have been developed; I am only familiar with this one.

0) get a coincident mount- this is a spherical mounting surface, with the center of curvature coincident with the off-axis parabola focus. Placing the off-axis parabola on the mount allows motion of the mirror to change the beam direction without adding aberration. Also, this provides access to the optical axis, allowing for 'normal' alignment methods to be used. Once you have the mirror placed within the coincident mount, proceed thusly:

1) Light source is placed at desired focal point location
2) Confocal mount placed on bench, and adjusted until reflected light is directed back at source.
3) Off-axis parabola, mounted in coincident mount, is mounted on the confocal mount
4) Off-axis parabola is steered such that the collimated beam points in the proper direction
5) Any fold mirrors in the collimated beam are tipped/tilted to bring collimated beams into coincidence
6) Fold mirrors near focal points are translated to move OAP focal points to desired locations.

In addition to coincident mounts, there are vertex jigs which can be used. as part of alignment methods.

 

[ndvcx]

Thx Cragar, but if you place the interfering flashlights densely enough, would there be a way to guarantee collisions such that you woud see less light by peering into the tunnel (where you can only see the one horizontal one aimed at you) ?