Basics of High-Speed Video Camera
In a typical high-speed camera, the memory for storing video images is located separate from the image sensor, and image signals are sequentially transferred from each sensor pixel to the memory. However, because the signal transfer rate is limited, the image resolution decreases as the recording speed increases.
Sequential Transfer of Video Signals from Each Pixel to the Memory
Low Recording Speed
Because the time interval between images or frames is long, a large number of pixels can be transferred per frame
High Recording Speed
Pixel volume that can be transferred per frame is limited due to a restricted signal transfer rate.
The burst method provides sufficient memory for the frame rate capacity directly on the image sensor and links every pixel to this memory through individual connections. Video signals stored in the memory during recording are then transferred externally once recording has ended.
The boundaries of the respective effective areas of the burst and readout methods range from approximately several hundred kfps to 1 Mfps.
The frame rate capacity of HPV series high-speed video cameras is limited so a recording trigger is essential to reliably capture phenomena. For instance, if the recording speed is 1 Mfps and the frame rate capacity is 256 frames, the recording time will be 256 µsec. By accurately adjusting the trigger signal delay, the trigger point, and the recording time (i.e., recording speed), the camera can reliably capture the phenomenon you wish to record.
High-speed video recording has a short exposure time, so it requires illumination by a light source with sufficient intensity.
Continuous Illumination
With continuous illumination, no illumination trigger signal is required. On the other hand, the light intensity may be insufficient in the ultra high-speed range. Prolonged irradiation may also cause the object to heat up, resulting in deformation or damage.
Strobe Illumination
Strobe illumination provides far greater light intensity than continuous illumination. However, the luminous intensity is not constant and there is a delay of several hundred microseconds (μsec) until peak illumination is reached. It also requires an illumination trigger signal because the illumination time that can be used in high-speed video recording is several milliseconds (msec).
Laser Illumination
Illumination with a laser enables pulse emissions of several tens of nanoseconds (nsec), which in turn enables ultra-short exposure times. Like strobe illumination, it requires an illumination trigger signal because there is a limit to the number of pulses. Pulse emissions can be synchronized with the timing of the high-speed video camera’s shutter.
