Hi Rodney,
Your suggestion re the Arduino is a good one. We used one of those (or one similar) to convert a scale Bleriot to a drone 4 or 5 years ago for a replica flight.
The sensors on it were great.
I had a hanger9 laser unit about 10 years ago. As it came the resolution was spoiled by the drag in the bearings.
I solved this by removing the balancing thumb screw and remounting it on a home made bracket which was made to hang it about 120mm to 150mm lower.
This increased the pendulum effect by something in the order of 300% to 500% and completely cured the resolution issues.
It then had to mounted on the rear of the bar (clear of the panel being measured).
However I made a new scale for a longer bar and it was accurate to and resolving to inside 0.025*.
Downside ; It was a pig on batteries
We forked out for an Aeroperfect when it came along. A few of us got one between us, including Niall above. Cheap when spread over multiple F3A models.
Unfortunately he has supply chain issues now.
There is a gap in the market for something of high quality.
Brian