Re: What Kind of Eyepiece

"Tom Hubin" <thubin@xxxxxxxxxxxxx> wrote in message
news:44EA1696.2EB6@xxxxxxxxxxxxxxxx
Hello,

I have a well illuminated 16mm diameter flat colored object inside a
container and located 30mm from a 5mm diameter viewing port.

I need to view the object with an eyepiece, or collection of air-spaced
lenses, that provide a reasonable eye relief for eyeglass wearers. Let's
say 15mm to 20mm eye relief and a 5mm to 10mm exit pupil and something
close to a 30 degree full field of view.

Resolution on the order of 1% of the object diameter is adequate.

The location and size of the viewing port seems incompatible with the
eyepiece specs that I have looked at. I need to know the class of
eyepiece lens or optics to look for. If I can find a commercial lens
that is close then I can alter some of my parameters to better fit the
lens.

******************************

Dave Schaack wrote:

Tom, this is not a standard eyepiece application, so a standard eyepiece
won't work well. An eyepiece is designed for a system with the aperture
stop far from the eyepiece, with the object near the eyepiece. At first
blush, you have the aperture stop between the object and the "eyepiece".
This is more akin to a door peephole viewer than to an eyepiece.

My suggestion is that you get a competent optical designer to spend some
quality time with your problem. The quality time would start by inquiring
very closely into how much light is actually needed in the viewed image and
comparing that with how much light is actually available and also whether it
is possible to insert something a considerable distance into the viewing
port.

*********************

Hello Dave,

Thanx for your attention to the details. I agree that it is more like a
door peephole and not like most eyepiece applications. Any suggestions
there?

I only want to make a couple of devices and this is for a hobby. Might
make a buck on it someday but not lilely. So the cost of a pro is not in
the budget.

I have paraxial solutions that solve the problem but the 2 or 3 lenses
will probably not be catalog achromats.

For example, I could have a 30mm focal length lens at the peephole then
an afocal convex pair of lenses to relay that peephole 1:1. Combined
focal length is -30mm and the image is inverted. No problem there.

The afocal pair can be shifted left until the first lens of the afocal
pair is superimposed on the peephole lens. This produces a 2 lens
solution.

All of this is ok. But now the effort is on finding or making the 2 or 3
lenses so that aberrations are acceptable.

I plan to raytrace these solutions, and maybe other math solutions, with
catalog lenses. Maybe tweak the curves to see if I can improve the
image. But the high cost of manufacture stops me from seriously
considering custom lenses.

So, I am asking around to see if there is an application for which the
lenses are suited to my problem. Your suggestion of door peephole optics
is worth exploring since I can tolerate a fair amount of distortion.

About inserting within the space...no can do. There are things happening
in that space between the object and the peephole.

Tom Hubin
thubin@xxxxxxxxxxxxx

.

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