DataRay Blog

M² and High-order Modes

M² is a measurement that was originally designed to determine the quality of a real beam in comparison to a theoretically perfect fundamental mode Gaussian beam (Siegman 1990). Although many lasers are designed to output a fundamental mode Gaussian beam, imperfections and/or cavity design in the laser will often cause superimposed higher-order transverse modes. M² provides an excellent metric for determining the higher-order mode content. In his original paper introducing M², Siegman gives mathematical expressions for the theoretical value of M² based on the weighted content of the various modes in a beam. In this blog post, we will programmatically generate Gaussian beams with multi-mode content and then analyze the M² value of these artificial beams calculated by the DataRay software in order to confirm the accuracy of our algorithms.

M² Measurement

As leaders in the laser beam profiling business, we have worked with M² for decades. In this blog post we discuss M², when to use it, and the way it is measured. M² is a very useful measurement for a certain subset of laser beams—those that are predominately Gaussian—and determines how tightly an actual laser beam can be focused in comparison to a theoretically perfect Gaussian beam. Sometimes, customers wish to use M² as a laser beam metric, even when it isn't the most appropriate metric to use for their application. Even if M² isn't the right diagnostic metric for your beam, we would love to work with you and design a custom metric to assess the quality of your beam.

CMOS vs. CCD Sensors and Overview

CMOS and CCD image sensor technology was developed in the 1960s. Although for the last forty years CCD sensors have dominated the market, improvements in CMOS sensor design have catapulted them to a growing market share and the CMOS seems poised to replace the CCD in many applications. Often times, customers familiar with the past advantages of CCD sensors question the use of CMOS image sensors in laser beam profiling cameras. We seek to provide a short overview of the CMOS sensor’s advantages and the improvements that have enabled it to become a contender in the image sensor market.