In Sept. 1998 we installed a 60 um stroke (mechanical) piezo driven by a Physic Instrumente amplifier (PI E-662). The input to the PI amplifier is a 0-10 V (for full 0-60 um displacement) triangle wave from a frequency generator (FG), at selectable frequencies, as before. We use a FG that also generates a TTL pulse at the peak of each triangle, which is the signal required by the Quadra to tell the Pentium to initiate a scan data acquisition (also as before). I made drawings by hand on how to connect the piezo, FG and PI amplifier and they are in the ring binder manual at the site. I will include those drawings in this document soon. The new piezo also has a new, better, optical mount.
The longer stroke allowed a new, slower, readout mode while still keeping
the fringe frequencies above 100 Hz. Also, the sampling rates and fringe
frequencies are now different. We still sample 256 data points per scan.
Therefore, the updated tables with those parameters are as follows. Note
that I have changed the nomenclature of the readout modes in order to accommodate
the new one in a logical sequence.
| Mode | Samples/Frames | Reads/Sample | Set Scanning Freq. to | Sampling Time |
| 1 | 8 | 4 | 0.9 Hz | 2.05 ms |
| 2 | 4 | 4 | 1.9 | 1.03 |
| 3 | 3 | 4 | 2.6 | 0.75 |
| 4 | 2 | 4 | 3.7 | 0.52 |
| 5 | 1 | 4 | 7.6 | 0.25 |
| 6 | 1 | 1 | 10.6 | 0.18 |
| Mode
------ Filter |
1 | 2 | 3 | 4 | 5 | 6 |
| J | 185 | 359 | 494 | 712 | 1481 | 2058 |
| H | 143 | 277 | 381 | 549 | 1143 | 1587 |
| K | 106 | 206 | 284 | 409 | 851 | 1182 |