The Technique (IMAGE) University of Copenhagen - Niels Bohr Institute Caption The laser light is sent through a "resonator," which consists of two mirrors. This resonator selects specific wavelengths. A vacuum chamber containing ultra cold atoms is placed in between the two mirrors and acts as a frequency filter. As a result, the laser can be stabilized much better than with just the empty "resonator." Credit (Credit: Bjarke Takashi R&ostroke;jle Christensen, Niels Bohr Institute) Usage Restrictions (Credit: Bjarke Takashi R&ostroke;jle Christensen, Niels Bohr Institute) 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.