You can work in either a static mode where you upload your beam image, or in a dynamic mode where the software will give measurements in real time. We have developed an open source tool that will help you analyze your beam profile. These measurements can be time consuming, so it’s better if the sensor is placed on a motorized translation stage to automate this process. This measurement can be made using the knife-edge method or the scanning slit measurement. Use the regression equations detailed in the norm to fit a hyperbola to your data points for both the X and Y axes.įrom this fit, extract the values for θ, w0, zR, and M2 for each axis. Measure the diameter of the beam at various positions around the focal point: take at least 10 data points, approximately half within the first Rayleigh distance of the focal point, and the other half beyond 2 Rayleigh lengths. However, the ISO 11146 norm explains a method to calculate M2 from a set of 10 beam diameter measurements. This makes it possible to estimate the beam divergence and waist. In order to calculate the M-squared factor, you will need at least two measurements. The larger the M-squared factor is, the farther away from a Gaussian beam our laser beam will be. It’s easy to show that for a perfect Gaussian beam, the M-squared factor will have a value of 1. Furthermore, if we assume that the divergence of a Gaussian beam is given by: Where w is the beam waist, θ is the divergence angle, and ? is the laser wavelength. The M-squared factor is defined by the ISO Standard 11146 as:

We are basically comparing the divergence and beam waist size to that of a Gaussian Beam. The M-squared factor is useful when we have laser beams that need to be focused. It is the last one that we want to talk about today. Some of the ways to characterize a laser beam are: beam parameter product, Strehl ratio, and beam quality factor (or M-squared). First, we need to understand that there are different ways to calculate the quality of a laser beam.

Beam divergence calculator