Optical aid adventure

[hman]

Re: Optical aid mystery

When the prism is very close to the surface you wish to center (a couple of mm) you see the surface very accurately (i.e. at the same position) no matter the angle your eye is in relation to the vertical side of the prism.
In other words it doesn't matter if you are in position "A" or "B" or "C" you see the hole to the same place
....
when you move the prism at a height from the surface you want to center ... I found out that happens exactly what happens when you look through a mirror.

Indeed, once you get “outside the glass,” a Porro prism is nothing but a mirror.

In pure english it means that for a prism or a fiber optic surrounded by air if the angle is 45 deg or more we have TOTAL INTERNAL DEFLECTION

....
Solution: leave the long side clean of glue as I did in the first tool I made

I was thinking of this very thing when I read your first post. I’ve actually seen similar prisms (for astronomical use) with pieces of black paper against the reflecting face. I think this is to be sure that stray light isn’t transmitted into the prism. And if nothing else, it will help protect the back side of the prism from any stray glue.

NEW DISCOVERY

So I have solved the mystery of no reflection and, if the prism touches air and no glue at the long side I also discovered that you can light the surface below from the front of the prism!! (see below)

View attachment 87665

You might have some fun using my “beamsplitter” illuminators between your eye and the Porro prism. (See also post #2125 in Project of the Day.)

CONCLUSION
It was a learning journey for me! A real adventure! I enjoyed every moment of the construction and, within its limitations, the tool is very accurate and easy to use.

Thank you for reading this

Thank YOU for an inspiring idea!

 

[petcnc]

Re: Optical aid mystery

Indeed, once you get “outside the glass,” a Porro prism is nothing but a mirror.

I was thinking of this very thing when I read your first post. I’ve actually seen similar prisms (for astronomical use) with pieces of black paper against the reflecting face. I think this is to be sure that stray light isn’t transmitted into the prism. And if nothing else, it will help protect the back side of the prism from any stray glue.

You might have some fun using my “beamsplitter” illuminators between your eye and the Porro prism. (See also post #2125 in Project of the Day.)

View attachment 87695

Thank YOU for an inspiring idea!

Thanks for giving me new ideas to test on the "optical aid tool v.2"
Is it collaborative thinking or what?

Petros