Overlapping Cycles - Single timing

Timing diagrams of overlapping CIC cycles with identical cycle timing definition

This topic describes the behavior of the CIC when it is configured to generate one sequence of 4 cycles, each with identical timings settings.

In the following timing diagrams, user-defined values are shown in red:

● c is the minimum cycle period defined by CycleMinimumPeriod,
● d is the Strobe delay defined by StrobeDelay,
● e is the Camera Trigger pulse width defined by ExposureTime,
● r is the minimum time interval between consecutive exposure defined by ExposureRecoveryTime,
● s is the Strobe pulse width defined StrobeDuration.

In the following timing diagrams, values calculated by the driver are shown in blue:

● a is the CIC cycle duration,
● f is the time interval between consecutive Camera Trigger pulses,
□ the Strobe pulse width. This is the value of StrobeDuration set by the user.

The driver calculates the duration of the CIC Cycle (a value)from the user-defined settings ExposureTime, ExposureRecoveryTime and CycleMinimumPeriod by searching the smallest value satisfying the following conditions:

● Condition 1: The time interval between consecutive Camera Trigger pulses (f value) must be greater than or equal to the ExposureRecoveryTime settings (r value). This ensures that the Camera Trigger properly flows through the trigger transmission link. It ensures also that a new exposure doesn't begin before the completion of the previous one.
● Condition 2: The CIC Cycle duration (a value) must be big enough to ensure that a new readout doesn't begin before the completion of the previous one.
● Condition 3: The CIC Cycle duration (a value) must be big enough to include both transitions of the Camera Trigger and the Strobe signal.

The "Readout-limited" use cases illustrate situations where the cycle period is equal to the duration of the readout phase.

The "Exposure-limited" use cases illustrate situations where the cycle period is equal to the duration of the exposure phase.

The camera cycle rate is only limited by the camera readout time

This situation occurs when the exposure time (e value) is significantly smaller than the readout duration (c value). In that situation:

● f is likely larger than ExposureRecoveryTime: Condition 1 is fulfilled.
● The strobe pulse being "inside" the Camera Trigger pulse: Condition 3 becomes irrelevant when Condition 1 is fulfilled.
● The Condition 2 is the only condition used by the driver to calculate the cycle duration.

The optimal duration of the CIC Cycle is equal to the effective duration of the sensor readout phase. This is obtained when the user sets CycleMinimumPeriod to a value corresponding to the readout duration.

NOTE: The readout duration can be derived from the maximum frame rate specification of the camera data sheet or experimentally.

The camera cycle rate is only limited by the camera readout time (despite the early strobe)

This situation is similar to the case 1. It shows that despite an early strobe, it is possible to reach the maximum cycle rate of the camera.

This situation occurs when the exposure time (e value) is significantly smaller than the readout duration (c value). In that situation:

● f is likely larger than ExposureRecoveryTime: Condition 1 is fulfilled.
● The strobe pulse being terminating before the Camera Trigger pulse: Condition 3 is fulfilled if r is greater than d. This is the case when (d + e < c).
● The Condition 2 is the only condition used by the driver to calculate the cycle duration.

The optimal duration of the CIC Cycle is equal to the effective duration of the sensor readout phase. This is obtained when the user sets CycleMinimumPeriod to a value corresponding to the readout duration.

NOTE: The readout duration can be derived from the maximum frame rate specification of the camera data sheet or experimentally.

The camera cycle rate is limited by the exposure time settings

This situation occurs when the exposure time (e value) is significantly larger than the readout duration (c value). In that situation:

● All cycles being identical, having the readout duration smaller than the exposure duration, implies that Condition 2 becomes irrelevant.
● The strobe pulse being "inside" the Camera Trigger pulse: Condition 3 becomes irrelevant when Condition 1 is fulfilled.
● The Condition 1 is the only condition used by the driver to calculate the cycle duration .

The optimal duration of the Cycle is equal to the effective duration of the exposure phase. This is obtained when the user sets ExposureRecoveryTime to a value corresponding to the minimal time interval allowed by the camera between consecutive Camera Trigger pulses.

The camera cycle rate is limited by the exposure time settings (despite the early strobe)

This situation is similar to the case 3. It shows that despite an early strobe, it is possible to reach the same cycle rate win case of small negative StrobeDelay values.

This situation occurs when the exposure time (e value) is significantly larger than the readout duration (c value). In that situation:

● All cycles being identical, having the readout duration smaller than the exposure duration implies that Condition 2 becomes irrelevant.
● The strobe pulse terminating before the Camera Trigger pulse: Condition 3 becomes irrelevant when Condition 1 is fulfilled and d < r.
● Condition 3 and Condition 1 are the only condition used by the driver to calculate the cycle duration.

The user must set ExposureRecoveryTime to a value corresponding to the largest of the following two values:

● Minimal time interval allowed by the camera between consecutive Camera Trigger pulses.
● Opposite value of StrobeDelay.
NOTE: When CycleTriggerSource = Immediate, the cycle rate can be lowered to the desired rate by assigning a greater value to CycleMinimumPeriod.