ACQUIRING DATA
iKon-L SECTION 5
Page 79
• Fully Auto is the simplest shutter mode, as it leaves all shuttering decisions to the system. When you
perform Take Signal the shutter opens for the duration of the Exposure Time you have entered in
the Setup Acquisition dialog box.
NOTE: This option will automatically provide suitable shuttering for the majority of data acquisitions.
The shutter will be closed for background data acquisitions and will be opened for all other data
acquisitions.
• If CLOSED for background mode is selected, any shutter driven from the Shutter output will be
closed as you perform Take Background. If you want the shutter to be open so that the Take
Background function records genuine optical background data, deselect the option. NOTE: Usually a
background scan is used to subtract the dark signal and the Fixed Pattern Noise (FPN) of the
sensor. For this reason the background scan is usually performed in darkness. A shutter may
be used to stop light entering the spectrograph or other imaging system. Strictly speaking
though, the background acquisition may be regarded as comprising all light with the single
exception of the source. Thus, when you are working with a pulsed or independently shuttered
source, it may be appropriate to have the mode deselected.
• In Permanently OPEN mode, the shutter will be open before, during and after any data acquisition.
• Permanently CLOSED mode can be useful if you want to take a series of acquisitions in darkness
and do not require the shutter to open between acquisitions. You might, for example, wish to capture
a sequence of background values. The shutter remains closed before, during and after any data
acquisition.
The TTL (Transistor-Transistor Logic) buttons, TTL Low & TTL High, let you instruct the system as to how it
should control the opening and closing of the shutter. An illustration of the TTL structure is shown on the next
page.
If you select TTL Low, the system will cause the output voltage from the iKon-L to go ‘low’ to open the
shutter.
If you select TTL High, the system will cause the output voltage from the iKon-L to go ‘high’ to open
the shutter.
NOTES:
1. The documentation supplied by the shutter manufacturer will show whether your
shutter opens at a High or a Low TTL level.
2. If a shutter is fitted but not required for the experiment then set it to Permanently OPEN
and Time To Close = 0. This will allow the system to operate at its optimum rate. If a
background is req
uired then close the shutter using Permanently Closed, Take
Background and reopen.
3. The shutter pulse is not capable of driving a shutter. It is only a 5V pulse designed to
trigger TTL & CMOS compatible shutter drivers. Also there is no shutter pulse during
the Take Signal and Take Reference data acquisitions.
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