In the ophthalmological system, images are built up from a series of pulses.
眼科用的是脉冲成像的方法。
英语百科
System image
In computing, a system image is a serialized copy of the entire state of a computer system stored in some non-volatile form such as a file. A system is said to be capable of using system images if it can be shut down and later restored to exactly the same state. In such cases, system images can be used for backup.