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Functions and Operations
the application in a dark area and depend on a strobe light for illumination. From the time the external trigger activates until the transfer gate turns off, about 9.5 video lines are available for integration; if everything is properly configured, the strobe flashes during this time.
FIGURE 54. External Trigger Timing.
6.4.4Asynchronous Programmable Exposure Mode
In Asynchronous Programmable Exposure Mode, when an external trigger is applied, the exposure starts after one discharge signal (Vsub), which happens after the trigger’s active edge is off. Because the discharge signal (Vsub) synchronizes with LDV in this mode, there is a maximum one video line of jitter between the trigger active edges to discharge signals (Vsub) off. In this mode, the exposure time from 1 video line to 2080 video lines can be controlled through serial communication commands in one video line steps. In this mode, the minimum exposure time is equal to 1 video line plus overhead: the maximum exposure time is equal to 2080 video lines plus overhead. Where the specified exposure time is n video lines, the real exposure time is equal to:
ExposureTime = | ⎧(n +1) *32.5 μs + 25.6μs | Dual tap | (n = 0,1,......2079) |
⎩⎨ (n +1) *58.1μs + 25.6μs | Singletap |
When n=0, the exposure time is minimum exposure time. It is equal to:
Minimum ExposureTime = | ⎧58.1μs (1/17000 s) | Dual tap |
⎩⎨ 83.7μs (1/12000s) | Singletap |
When n=2079, the exposure time is maximum exposure time. It is equal to:
Maximum ExposureTime = | ⎧67625.6μs (1/15 s) | Dual tap |
⎩⎨ 120873.6μs (1/ 8 s) | Singletap |
When n=2079, the exposure time is maximum exposure time. If the exposure time is less than the time available for one frame, the maximum trigger frequency is equal to 1/1 frame time. If the exposure time is longer than the time available for one frame, the maximum trigger frequency is equal to 1/exposure time.
The minimum active period of the external trigger is 5μs.
