Re: Camera software

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Dennis Schmitz"
<denschmitz@...> wrote:

>
> In order for the stereo cameras to do depth measurements, they'd
>need to see the same speckle pattern. The way I understand
>interference, they should see different patterns in each camera.

if you shine the beam at a rough surface and look at it then two
different cameras would see two different speckle patterns but if you
shine the light through a diffuser, the speckle pattern is produced on
the object itself and the observation optics should not effect it.

> If you use a laser pointer, the beam cross-section is pretty small
> (about 1mm on my green one), but the speckle pattern you see on a >
>wall is much bigger.

err if shone through a diffuser it is spread, otherwise it is simply
because of the divergence of the beam.

>Why? I understood that the reflection was still pretty
> coherent leading to a visually larger spot of speckle than was being
> exposed to by the laser because of the way it reinforces at your
> retina. Is this not correct?

No it is not correct.

>If so, then the whole reflected speckle
> pattern that I can see is generated by the texture under the 1mm >beam.

If I shine a laser at a wall I just see a dot the size of the beam at
that point.

> What I thought would work would be a hologram beam spreader like the
> ones you screw on the end of a laser pointer.

Diffractive optic elements are just moulded plastic parts that do the
same thing as the rough glass however they are designed such that the
fringes combine to form a certain shape like a cross hair or just to
act as a lens.

Graham