Photon Focus MV1-D1024E, User Manual, Page: 36 / 109

4 Functionality
4.4 Trigger and Strobe
4.4.1 Introduction
The start of the exposure of the camera’s image sensor is controlled by the trigger. The trigger
can either be generated internally by the camera (free running trigger mode) or by an external
device (external trigger mode).
This section refers to the external trigger mode if not otherwise specified.
In external trigger mode, the trigger can be applied through the CameraLink
®
interface
(interface trigger) or directly by the power supply connector of the camera (I/O Trigger) (see
Section 4.4.2). The trigger signal can be configured to be active high or active low. When the
frequency of the incoming triggers is higher than the maximal frame rate of the current
camera settings, then some trigger pulses will be missed. A missed trigger counter counts these
events. This counter can be read out by the user.
The exposure time in external trigger mode can be defined by the setting of the exposure time
register (camera controlled exposure mode) or by the width of the incoming trigger pulse
(trigger controlled exposure mode) (see Section 4.4.3).
An external trigger pulse starts the exposure of one image. In Burst Trigger Mode however, a
trigger pulse starts the exposure of a user defined number of images (see Section 4.4.5).
The start of the exposure is shortly after the active edge of the incoming trigger. An additional
trigger delay can be applied that delays the start of the exposure by a user defined time (see
Section 4.4.4). This often used to start the exposure after the trigger to a flash lighting source.
4.4.2 Trigger Source
The trigger signal can be configured to be active high or active low. One of the following
trigger sources can be used:
Free running
The trigger is generated internally by the camera. Exposure starts immediately
after the camera is ready and the maximal possible frame rate is attained, if Constant
Frame Rate mode is disabled. In Constant Frame Rate mode, exposure starts after a
user-specified time (Frame Time) has elapsed from the previous exposure start and
therefore the frame rate is set to a user defined value.
Interface Trigger In the interface trigger mode, the trigger signal is applied to the camera by
the CameraLink
®
interface. Fig. 4.24 shows a diagram of the interface trigger setup. The
trigger is generated by the frame grabber board and sent on the CC1 signal through the
CameraLink
®
interface. Some frame grabbers allow the connection external trigger
devices through an I/O card. A schematic diagram of this setup is shown in Fig. 4.25.
I/O Trigger In the I/O trigger mode, the trigger signal is applied directly to the camera by the
power supply connector (via an optocoupler). A setup of this mode is shown in Fig. 4.26.
The electrical interface of the I/O trigger input and the strobe output is described in
Section 6.1.3.
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