NASA Langley Research Center's 737 'flying laboratory' flight tested three advance warning windshear sensors. The laser beams seen in the photograph were used to align the optical hardware of the infrared (located in front of the windows) and LIDAR (Light Detecting And Ranging) systems. In addition, a microwave doppler radar system is installed in the aircraft nose.
NASA
<a rel="nofollow" class="external free" href="http://www.nasa.gov/centers/langley/news/factsheets/B-737.html">http://www.nasa.gov/centers/langley/news/factsheets/B-737.html</a> (<a rel="nofollow" class="external text" href="http://www.nasa.gov/centers/langley/images/content/470701main1_737runway-226.jpg">direct link</a>)