OEMs of precise inspection systems such as those used in FPD and semiconductor manufacturing, are continuously working to increase throughput and reduce costs.
One way to increase throughput in such a system is to decrease the amount of time the object needs to be under the camera system for measurement. A shorter integration time supported on the sensor of the camera is one such feature that allows objects to move faster in front of the camera without being hampered by motion blur. Motion blur is especially a problem in systems with high magnification and/or utilizing flying scan detection where the camera continuously moves over the object under test.
With this ability on the shutter performance of the camera also reduces the lighting complexity and costs for the system. Strobe lighting solutions become expensive especially at light pulse time below say 30 microseconds.
To support our customers in such applications, we recently made a modification to our Quartz and Qs series of cameras which utilize CMOSIS 4 MP CMOS sensors (CMV4000). The Frame overhead time (FOT) of the sensor is the setting that determines the time between end of sensor integration and start of sensor readout. During a fixed percentage of the FOT, the pixels are still photo sensitive. Therefore, the FOT setting determines the minimum integration time. A change to the specification of the FOT of the sensor allowed for the minimum integration time to be reduced from 24 microseconds to 12.5 microseconds. For now, this is the shortest integration time possible with these sensors that will not compromise image quality.
If even shorter integration times are beneficial, CCD-based cameras are the solution. For instance, our OPAL cameras with 1, 2, 4, and 8 Megapixels have (standard ) a minimum integration time of 10 microseconds. Adimec has experience with a minimum integration time at 1.5 microseconds in our CCD cameras. We can provide customer special products based on this. This is one area where CCD continues to have a big advantage.
So for systems with continuous motion, the minimum integration time is an important consideration.