Optical Tweezers (IMAGE) Technical University of Munich (TUM) Caption Two laser beams hold tiny glass beads in a position very close to each other. One end of the protein complex is fixed on the surface of the left brad, the other end on the right. If the laser moves the glass beads apart, the protein molecules are forced to stretch and the forces can be measured. Credit Marco Grison / TUM Usage Restrictions None License Licensed content 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.