Ocean Optics SIR Series - Manual (Page 11)

07-December-2010
6.0 External Triggering and interfacing:
The SIR spectrometer can support several modes of synchronization with
external events. The default mode of operation is a free running mode and
requires no external interfacing. In cases that require external synchronization,
such as with optical chopping or triggering a laser or optical source, the
spectrometer can provide a 50% duty cycle clock which can be programmed in
.1ms increments. The spectrometer can also be synchronized with an external
trigger input. To accommodate the fact there is a finite amount of time between
when a trigger activates, and the external source reaches full power, a phase
delay option is available to adjust the amount of time between the rising edge of
the trigger, and when the spectrometer takes a sample.
To Access the trigger option menu, go to the MIR Control Menu.
The External Interface Tab is used to configure triggering
options.
Phase Delay: This is used to adjust the time between an incoming trigger and
the Analog to Digital Converter taking a sample. This can be adjusted in 0.1ms
increments. The time entered is one half of the period of the clock. In this
example the phase delay is set to 10ms.
Internal Clock: This is a clock that can be used to drive the external lamp clock
output. It can be adjusted in 0.1ms increments. The value set determines one
half of the period of the clock. In this example the clock will be high for 100ms
and low for 100ms, for a total clock period of 200ms, or a frequency of 5hz.
(1/200ms). The sample clock can be adjusted independent of the A/D speed
described earlier, but will only sample when it has completed it’s previous cycle.
The maximum is….
External Enabled: This field has a setting of True or False. A value of true in this
field tells the spectrometer to use the external input clock (plus phase delay) as
the trigger source. A value of false tells the spectrometer to use the internal clock
(plus the phase delay) as the trigger source.
Invert Phase: A value of false in this field makes the trigger source a rising edge.
A value of false here will enable the trigger source to be a falling edge.
Lamp Synchronize: A value of true in this field activates the synchronization of
the spectrometer. The source of the trigger is determined by the “External
Enabled” button above.