Princeton Instruments PI-MAX4, Manual

Page: 164 / 326

164 PI-MAX
®
4 System Manual Issue 9
Figure 9-10: Timing Diagram: Pre-Trigger, Dual Trigger (ShiftPer Trigger)
It is important to understand and remember that the
Pre-Trigger
input and the
Trigger
input(s) are independently generated using two external trigger sources. Therefore the
PI-MAX4 1024i has no knowledge of, or control over, the timing of when these signals are
received with respect to one another.
Proper DIF operation is dependent upon the completion of the first image acquisition cycle,
including sufficient phosphor decay time, before the acquired first frame of image data is
shifted behind the mask. Consequently, if the timing of an experiment’s external pre-trigger/
trigger(s) is not carefully planned and implemented, the first acquired frame of image data
may be corrupted or even non-existent.
For example,
Figure 9-11 illustrates the timing diagram for an experiment where the
Trigger
input is received too close to when the
Shift Behind Mask
operation is initiated.
Figure 9-11: Timing Diagram: Pre-Trigger With Slightly Late Input Trigger
t
PT
: Time between Pre-Trigger and
Shift Behind Mask
• P
S ± 2
P
S)
',QLWLDO*DWH'HOD\•,QVHUWLRQ'HOD\
W1: Pulse 1 Gate Width
TT: Time between triggers; •':3'
D2: Pulse 2 Gate Delay, •,QVHUWLRQ'HOD\
W2: Pulse 2 Gate Width
3'3KRVSKRU'HFD\7LPH
t
PT
PRE-TRIGGER
IMAGES
TRIGGER
D1
W1 PD
Shift Behind
Mask
FIRST FRAME
PD
D2
W2
SECOND FRAME
Pre-Trigger
Jitter
TT
44
11-0
139_0
183
IMAGES
TRIGGER
t
FF
FIRST FRAME
SECOND FRAME
t
PT
: Time between Pre-Trigger and
Shift Behind Mask • P S ± 2 P S)
t
FF
: Time to Acquire First Frame of Image Data
PRE-TRIGGER
t
PT
Shift Behind
Mask
Pre-Trigger
Jitter
441
1-01
39_01
91