Modified Pre-mode Cleaner (image) The Optical Society Share Print E-Mail Caption The researchers created a modified pre-mode cleaner (left) that compensates for astigmatism that affects a Laguerre-Gauss mode laser. The astigmatism arises when the laser hits curved mirrors at an angle. Using concave mirrors at position 1 and 2 and planar mirrors at positions 3 and 4 compensates for this optical error such that a clean Laguerre Gauss mode is transmitted (right). Credit Andreas Noack, Albert Einstein Institute Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.