7
Kentech Instruments Ltd., Unit 9, Hall Farm Workshops, South Moreton, Didcot, Oxon, OX11 9AG, U.K.
10th. July 1999
The following is a procedure we have used for timing the cells.
1
Set up the system and align as under static alignment.
2
It is much easier to look for transmission than extinction when one is using each channel of the pulser
independently. For timing tests it is better to rotate the output polariser, so that it is perpendicular
to that at the input.
3
Disconnect the DC cabling and connect one channel of the pulser to one cell. Note the timing of the
edge of the transmission curve with an oscilloscope.
4
Disconnect the pulser and in turn work through the other three channels, one at a time. Note that the
pulser must be connected to the cell that it will end up being used with. You cannot mix the channels
and cells as the cells require slightly differently timed drive pulses to achieve the same output timing.
5
Once all the timings are noted use one in approximately the centre of the range as a reference and
adjust all the others so that they are the same; see section 5.3.
Note the unit supplied is set up so that the timing is correct when the light enters from the right in figure 3 and
the pulser channels are connected as shown.
5.3
ADJUSTING THE TIMING OF THE CHANNELS.
The timing to each channel is adjusted by means of a set of four potentiometers on the trigger board. These are
a little hard to access. Care must be taken if operating the unit without the covers on the pulser. We strongly recommend
that the pulser is turned off and the mains disconnected before each adjustment is made, unfortunately continuous
adjustment whilst observing the effect is not possible with the unit turned off. It is likely that only small changes to the
timing will be necessary.
To change the timing:-
1
Turn off and remove the power from the unit
2
Remove the eight small cross point screws in the two sides of the unit.
1
2
3
4
Figure 3
The head showing the connections and direction of light propagation
