8.Features
© 2023 China Daheng Group, Inc. Beijing Image Vision Technology Branch 115
Line-by-line exposure sensor starts exposure at the same time in GRR mode, and the exposure ends
successively from top to bottom. As shown in the Figure 8-32, the exposure time is the common exposure
interval, which is also the interval that the flash lighting needs to be opened. That is, the exposure time
signal goes high when you can start the flash lighting, and the exposure time signal goes low when you
should stop the flash lighting. Otherwise, the brightness in the acquired images will vary significantly from
top to bottom due to the differences in the exposure time of the individual lines. In addition, the image will
be distortional due to different exposure end time of the individual lines.
The exposure delay is supported in GRR mode. At the same time, there is a certain delay due to the flash
lighting, and the actual duration of the flash is as follows:
T
strobe
= T
exposure
+ T
exp_delay
+ T
row
×18
Settings:
1)
Set the SensorShutterMode to Global Reset.
2)
Connect the camera to the flash lighting.
8.2.10.3.
Exposure Time Mode
According to the length of the exposure time, two exposure time modes of the MERCURY2 USB3 Vision
camera are available: Standard exposure time mode and UltraShort exposure time mode.
In Standard exposure time mode, three exposure time adjustment modes are available: manual
adjustment, one-time automatic adjustment and continuous automatic adjustment. The standard exposure
time mode is the default setting. For the manual adjustment, please refer to section 8.2.9. For the automatic
adjustment and continuous automatic adjustment, please refer to section 8.3.5.
In UltraShort exposure time mode, the MERCURY2 USB3 Vision camera only supports manual adjustment
of the exposure time. Since standard exposure time mode is the default setting, if you want to set the
UltraShort exposure time mode, you first need to adjust the visibility level to guru and set the
ExposureTimeMode to UltraShort under the acquisition control features window.
In UltraShort exposure time mode, the MERCURY2 USB3 Vision camera does not support
automatic adjustment of the exposure time, only support manual adjustment of the exposure time.
8.2.10.4.
Set Exposure Time
The MERCURY2 USB3 Vision camera supports setting the exposure time, step: 1μs.
The exposure precision of the camera is limited by the sensor, when the steps in the user's interface and
the demo display as 1μs, actually the steps are one row period. When the value of the ExposureTime
cannot be divisible by the row period, round up to an integer should be taken, such as the row period is
36μs, setting exposure time to 80μs, and the actual exposure time is 108μs.
When the external light source is sunlight or direct current (DC), the camera has no special requirements
for the exposure time. When the external light source is alternating current (AC), the exposure time must
synchronize with the external light source (under 50Hz light source, the exposure time must be a multiple
of 1/100s, under 60Hz light source, the exposure time must be a multiple of 1/120s), to ensure better image