Good Vibrations C O M M S urface vibration provides useful information for the surface and to subsequently analyze the reflected light. ER C products in a variety of industries. For example, The motion of the surface results in a Doppler shift that is IA L automobile manufacturers measure surface vibrations measured with very high precision. The Doppler shift B E to ascertain noise sources and to evaluate disk brake illustrates that sound waves have a fixed wavelength or N E performance. Surface vibrations provide aircraft distance between two crests. Simply explained, if a subject is FIT S manufacturers with valuable information about the structural moving away from the source, the sound wave will take a little — S quality of panels, turbine blades, and critical aircraft body longer to reach each crest, and a perceived longer wavelength PIN components. Musical instrument manufacturers measure the will be heard. In contrast, if the subject is approaching the O F vibration of their instruments to confirm purity of sound. source, the soundwave will meet each crest a little earlier, and FS A Small Business Innovation Research (SBIR) a shorter wavelength will be perceived. sponsorship from NASA’s Dryden Flight Research Center, Nicolet Instrument Technologies, of Madison, Wisconsin, assisted MetroLaser, of Irvine, California, in the development uses the laser diode vibration sensor technology in its Orion of a self-aligned laser vibrometer system. VibroMet, capable of Laser Doppler Vibrometer (LDV). The LDV is able to measuring surface vibrations in a variety of industries, measure the smallest vibration without the need for provides information on the structural integrity and acoustical scrupulous setup or surface preparation. The LDV can work characteristics of manufactured products. on almost any surface and is capable of off-axis Currently, the most common device used to measure measurements. Because Nicolet’s product is easy to use it is surface vibration is the accelerometer. Although useful in attractive to a variety of industries. Common uses of the some aspects, accelerometers are generally time consuming company’s product are rotating applications, such as and awkward to operate. In order to measure vibration, they automotive drive shafts, alternators, generators and tires; must be attached to the surface of the subject and wired to a multi-point measurements in machinery and modal analysis; recording system. In some cases, this may actually dampen surface vibration measurements in small structures such as the vibration measurement. On the other hand, laser hearing aids, tissue membranes and micro-sensors; as well as vibrometers provide a non-contact alternative to the applications in production testing, including hand tool accelerometer, eliminating the risk of an incorrect calculation. assemblies, electric motors, and piezoelectrics. MetroLaser’s research and development of the vibrometer The collaborative efforts of NASA and these companies led to the VibroMet system, which analyzes the frequency and have refined the laser vibrometer into a user-friendly, cost- amplitude returned from the surface evaluation. This low- effective surface vibration measurement system. VibroMet is cost, easy-to-use sensor performs vibration measurement from considered one of the many behind-the-scenes tools that can distances of up to three meters without the need for be relied on to assure the quality, reliability and safety of adjustment. The laser beam is simply pointed at the target everything from airplane panels to disk brakes. ❖ and the system then uses a compact laser diode to illuminate N A S A S P IN O MetroLaser’s VibroMet is a self-aligned, F F easy-to-use system for measuring surface ➤ vibrations that provide key information on the structural integrity and acoustical 2 0 characteristics of manufactured products. 0 1 INDUSTRIAL PRODUCTIVITY/MANUFACTURING TECHNOLOGY 111