Making and testing the 1 in 3 out all PMMA design

posted Jan 25, 2013, 7:44 PM by Sensorica Group   [ updated Jan 25, 2013, 7:50 PM by Tiberius Brastaviceanu ]
improved the electronic circuit for the tape sensor, adding variable gains (third version, see more on this evolving circuit prototype). This is a huge improvement!

Tibi assembled the 1 in, 3 out all PMMA design, connected it to the electronics and tested it with a mirror to see if there is sign of signal crossing, which is an indication that we can map small deflections in 2D. The screenshot below shows signal crossings for small angle variations of the mirror, placed 1mm away from the tip of the fibers.

3 signals from the 1 in 3 out all PMMA design, showing signal crossings

A video was also made to demonstrate this prototype. Next step is to assemble everything into a single wire, including the mirror on a lever, and test it on a 1m long beam. In order to optimize the sensitivity we'll keep the gap variable.

The making of this prototype

7 fibers were put together like in this picture
All 1mm PMMA fiber bundle

Since we only use 3 outer fibers to collect light, the other 3 were pushed back a little, in order to glue the remaining 4. 
assembly of the 7 PMMA fibers, after gluing

The remaining 4 fibers were polished
assembly to polish the 4 PMMA fibers at once

And tested shining light through them.
The 4 PMMA fibers - this pic is for assessing the symetry of the assembly. Light was whined into the fibers from the other side.

In order to ease the connections with the LED and PS a plastic tube was put over the tip of all fibers. The end results looks like this. The red one is the hot fiber, i.e. the one that brings light into the sensing area. The other 3 black ones are collecting fibers.
PMMA fibers, left is the polished end, where the miccor is going to be, on the right are the individual fibers with plastic tube over them, coming from an electrical wire. The red is the hot one, the one that brings light into the sensitive area. The black ones are the ones that bring light back to the 3 detectors.

Everything was connected to the electronics and tested.
3-th version of the electronic circuit made by Jonathan, with variable gain
the entire system, testing the 1 in 3 out all PMMA device
1 in 3 out all PMMA device - fibers in front of mirror