My company is working on a machine vision application. One of our requirements is that the camera peer through a frame (like a picture frame - see here ), where the top and bottom border are etched with machine vision targets. The frame is mounted on the gray rectangle (one side of a box) in the photo. The frame is 1/2" aluminum and about 14" long and between 3" and 8" high. The targets are laser etched. The top and bottom targets are parallel. For various reasons, we'd like to vary the gap between the targets. Our original thought is that we'd need to create a difference size frame (see picture below - red frame)
One of our engineers suggested that instead of building one frame for each size, we could make a vertical slot on either size of the box and position two rows of targets (actually two long pieces of aluminum) accordingly, somehow fastening them in the slot. We could use a metal spacer, measured to a particular gap to insure that the top and bottom row of targets are correctly oriented. Correct orientation means that the targets rows are parallel and are spaced to a known distance. My question is as follows. Is it possible to achieve high tolerances (e.g. 1/100mm) as it relates to orientation using the second approach? How would we do it?
Disclaimer: I'm not a mechanical engineer. Apologies if I'm not including important information (or if I've included irrelevant information).