White Cards (IMAGE) Penn State Caption This shows the same set of white cards as seen under a violet-pumped light emitting diode (LED) top, and under a blue-pumped LED below. Credit Patrick Mansell, Penn State Usage Restrictions non commercial use only 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.