Teledyne Princeton Instruments PI-MAX 3, Системное руководство

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Chapter 14 Picosecond Option 181
14.6 Methods for Finding a Short Optical Pulse
Method 1
The textbook method is to calculate all the delays in the optical and trigger paths and
set the PI-MAX3 delay accordingly. If one does all the arithmetic correctly and has
accurate numbers for all of the delays involved, this method will work.
In practice it seldom works because either some of the delays are not accurately known
or something gets overlooked. The sum of the optical delays must be greater than the
trigger delay (including the PI-MAX3 minimum delay.) Calculating the sums after the
fact is still a valuable check on the system, even if the timing is achieved using Method
2.
Method 2
A more direct and usually more convenient method is to start with a gate pulse much
wider than the optical pulse and configure the PI-MAX3 so the optical gate is wide
enough to be sure it encompasses the optical pulse. This method works well if the pulse
is conveniently repetitive, such as one derived from a repetitive laser.
Once the pulse is found, it is an easy matter to reduce the pulse width and adjust the
delay until the precise timing needed is achieved. The PI-MAX3 repetitive and sequential
gating can be used to good advantage in this method.
14.6.1 Example
This example is simplified in that it does not address all of the possible settings for Gate
mode setup. It is intended to a sense of how to locate the signal of interest by
successively decreasing gate pulse parameters.
Perform the following procedure:
1. Suppose we start with a 1

s gate and delay set to the minimum value for the
PI-MAX3 (approximately 25 ns,) and we see the pulse. We then know the pulse is
arriving between 25 ns and 1.025

s.
WinX/32 LightField
Number of Images/Spectra: 1
Gate Mode: Repetitive
Number of Frames: 1
Gate Delay: 25 ns
Gate Width: 1

s
4411-0129_0116