Laser Far-Field Focal Spot Measurement Method Based on Multi-step Phase Recovery

Laser far-field focus measurement is an important method for measuring laser beam power. The measurement of optical power is a key problem in many fields, such as laser technology, metrology, etc. In multi-step phase recovery on for high-precision measurement of the position and size of the far-field focus. The method can be divided into two steps: firstly, the spatial intensity distribution of laser beam is calculated by using the fast Fourier transform (FFT) algorithm; Secondly, it uses laser far-field focus measurement to measure the size of laser beam spot on an object. This method is based on phase recovery technology, which uses two or more measurements to determine the size of the object. The first measurement is carried out at a certain distance from the object, and then another measurement is carried out at a relatively close distance from the same object. If the size between these two measurements does not change, it can be assumed that the size of the focus itself does not change.