The polygon mirror rotates and scans the laser to perform measurement. When a target is moving, there will always be sections which cannot be measured as shown below.
Since the new optical system uses continuous exposure and no rotating mirror to measure a target, it reliably detects any changes in the target. This fully satisfies the need for high-speed line measurement due to shortened manufacturing tact time.
Temporary changes can be detected reliably because the measurement is based on the average value during the exposure time.
The laser path deviates depending on the surface accuracy of each surface of the scanning polygon mirror.
The laser scanning path varies for each sample.
With a laser scanning method, the variation in motor rotation becomes greater over time.
The longer the device is used, the greater the variation in the laser scanning path becomes.
This causes the system to need calibration often increasing cost and down time.
Since there is no moving mirror surface, the system measures the same area for every sample.