Hamamatsu Photonics C8484-16C Instruction Manual page 28

C8484-16C Instruction manual Ver.1.5
9-4-2-2 Exposure time setting: External setting
Exposure begins within 2.2 μs from the fall {rise} of the external trigger pulse. After this, when
external trigger pulse rises {falls} again, the exposure is stopped within the designated time,
and the data is read out. After readout, the system waits for the external trigger pulse to fall
{rise} again. The exposure time (electronic shutter time) is controlled according to the external
control pulse's LO interval {HI interval}. The repeat cycle is controlled by the external control
pulse's repeat cycle.
Note
• Set the external control pulse's repeat cycle so that it is longer than the minimum cycle.
Note
• The external control pulse's LO interval {HI interval} must be at least 10 μs.
Maximum exposure time is 1 s.
When the external control pulse's LO interval {HI interval} exceeds 1 s, the exposure is stopped
and the data is read out (exposure cannot exceed 1 s).
(1) Normal readout
Exposure and normal readout repeat according to the sequence set internally.
Command
External control pulse :
Scan mode
Exposure time
Designated time
Minimum repeat cycle can be calculated using the formula below.
Minimum repeat cycle = 83.8 ms (readout time) + external control pulse's
Exposure time can be calculated using the formula below.
Exposure time = external trigger pulse LO interval {HI interval} - 2.2 μs
Ex) When the external control pulse's LO interval {HI interval} is 40,
Exposure time = 40 μs - 2.2 μs (MAX) + 152 μs (MAX) = 189.8 μs (MAX)
External trigger pulse
CCD exposure
Electrical shutter signal
Readout signal
from CCD chip
Digital data output
26
: AMD E (External control mode)
ATP N {ATP P}
: SMD N (Normal)
: EMD L (External setting)
: within 152 µs
LO interval {HI interval} (exposure time)
(MAX) (exposure lock-in time) + 152 μs (MAX) (readout
lock-in time)
Pulse width min. 10 µs
max. 2.2 µs
max. 152 µs
Readout period