Stanford Research Systems SR470, Operation Manual

Page: 23 / 64

1.2 Front-Panel Operation 1 – 11
a value for either
f
or T
total
. This can be performed with the [ ] or
[ ] arrow keys, or by typing a valid value and entering it. (It is not
necessary that the entered value be di
ff
erent from the existing value,
but note that a new T
total
must be greater than or equal to T
pre
+
T
exp
,
and that a corresponding rule applies to a new value of
f
.)
Once in frequency priority mode, changes to T
pre
or T
exp
will not
change T
total
(which remains constant) but will instead only change
the value of the elastic parameter T
post
. Entering a new value for
T
total
(or
f
) will similarly a
ff
ect the value of T
post
, but leave T
pre
or
T
exp
unchanged. An error message will be displayed if a timing value
is requested that is not possible by changing only T
post
, for example,
if T
pre
=
T
exp
=
T
post
=
1 s, and T
total
were requested to be changed
from 3 s to 1 s.
To exit frequency priority mode and restore delay priority mode,
enter a value for T
post
. As with entering a value for T
total
to enter the
mode, this can be performed with the [ ] or [ ] arrow keys, or by
typing a valid value—changed or not—and entering it.
1.2.4.5 Bursts and continuous mode
The timing diagram discussed in
§
1.2.4.1 represents a single exposure
cycle, with an exposure bracketed by a predelay and postdelay .
A burst consists of a set of single exposure cycles that are triggered
continuously, one after the other. The burst count , the number of
cycles that will execute after a trigger is received, can be accessed by
pressing the [Burst] located in the “Mode” section of the front panel.
When selected, the enunciator “Count” will be illuminated to the left
of the numeric display and the value will be displayed. Using the
keypad and arrow keys, any value between 1 (the default value; a
single cycle) and 99 999 999 can be entered.
As a special case of using bursts, it is also possible to configure
the SR470 to cycle forever after a trigger is received. This is called
infinite burst or continuous mode, and can be selected by press-
ing [Shift][Continuous]. When this mode is selected, the word
“ ” will appear on the numeric display, and the
enunciator “Cont.” on the left of the numeric display will light up
and remain lit so long as
continuous mode is selected. It is also
possible to enter continuous mode using the [ ] and [ ] arrow keys,
by adjusting to a value less than 1 or greater than 99 999 999. Exit
continuous mode by entering a nonzero, finite value for the burst
count.
SR470 Shutter Controller