Hi Gordon:

You have two related issues in your problem. 
1. Sufficient resolution for decision making
2. Intuitive control of positioning

The former can be easily addressed by using the right optics
with the existing TV camera. Incidentally, the NTSC-based TV camera
alone has a good enough resolution for most inspection tasks.
It is the frame grabber, used to acquire and analyze the images
automatically, that decides the maximum detail for decision making.
I agree that there is no unique solution to looking at the heel
fillet other than the mirror arrangement that you investigated and
another microscope lens that I saw at NEPCON. This lens rotates about
the joint in focus giving you a sort of 3D feel for the joint.
I'll post the name of the company that makes /distributes
that lens as soon as I can get hold of it.

For the positioning, we have developed a point-and-click interface
for our Integrated SMT Inspection and Rework Cell which uses a 
scanned-in bitmap of the board as a guide. The user simply
clicks on the image at the pin he/she wants to inspect, and
the X-Y table moves there. We have implemented on a PC with a number 
of table drivers and it is fully extendible. Depending on the
calibration (which has been greatly simplified), and the accuracy
of the table, the software can position boards with high accuracy.
We are currently using it to create defect maps based on X-ray 
Laminography for communicating with our automated Rework cell.
That's one way to take care of the problem you described.

-- 
Vijay Sankaran          (518) 276-2721          [log in to unmask]
Research Associate
Center for Integrated Electronics and Electronics Manufacturing
Renssleaer Polytechnic Institute
Troy, NY 12180

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