 Other strategies for reducing the impact of the interface reflections include designing the LED to reabsorb and reemit the reflected light (called "photon recycling") and manipulating the microscopic structure of the surface to reduce the reflectance, by introducing random roughness, creating programmed "moth eye" surface patterns.Recently photonic crystals have also been used to minimize back-reflections.In December 2007, scientists at Glasgow University claimed to have found a way to make LEDs more energy efficient, imprinting billions of holes into LEDs using a process known as nanoimprint lithography.