Re: Acute angle projection (variable/stretched focal point?)

On May 14, 3:02 am, saluki...@xxxxxxxxx wrote:
Hello,
I'm a product design engineer and I'm here today because I'm stumped
by an optics problem, and I hope that someone with more experience can
help me out.
I'm currently trying to educate myself on what practical options are
available to project an image on a surface which is nearly paralell to
the projection direction, as opposed to the ideal, which would of
course be perpendicular.  I have about an inch and a half of space to
rise above the intended projection surface, and so I was thinking a
reflector would be the best option to help maximize my available
distance.  I believe the term that best describes my intent is 'acute
angle projection'.

I took a shot at creating an optics diagram to better illustrate my
goal, and though I'm sure that there are errors in the light path, I
hope that it will help to clarify my arrangement.
I realize that there is an inherent problem in that traditional optics
bend light to a focal point.  By definition, a system with a focal
point converges to a single point which can be adjusted to clear
focus.  Because of my angle, the problem I have is that this point is
stretched.  The result I have achieved is a clear image projected at
center, and blurring quickly out of focus from that point.  My hope is
that I can find an arrangement or cut a custom lens that will
essentially have a variable or 'stretched' focal point which is the
inverse of the projection blur.

I've spoken with a several optics manufacturers, but all seem to be
experienced in more traditional optical engineering tasks.

In considering this problem, I have thought of a few ways where it
seems that it should be possible.  One theoretical example is to
imagine the image broken into 1000 "pixels".  Each pixel of light
could then be directed through one of 1000 individual lenses and out
to the resulting end image, each maintaining its individual focal
point, and producing and end result that is in focus in spite of its
orientation.  Effectively, 1000 pixels = 1000 lenses = 1000 focal
points.  This thought makes me wonder if I averaged the geometry of
said lens 'group' if that would deliver a shape which would achieve my
goal.  (a parabola, perhaps?)

I've considered some Fresnel type layered solutions, or a lenticular
sort of optic, but still haven't made any solid conclusions.

I'm still educating myself in the realm of optical engineering, so I
would greatly appreciate any insights, experience, or other
suggestions to help resolve this problem.

Thanks in advance for any help!!
-Kevin Dahlquist
<img src="http://i59.photobucket.com/albums/g309/salukikev/
lightdiag.jpg">

The solution is actually quite easy. Tilt the object plane with
respect to the projection lens and your object plane will also be
tilted.
.