In a series of experiments during the summer of 1989 using laser interferometry to study auditory transduction and motion, the PIs observed that a small amount of light back-reflected into a He-Ne gas laser cavity by a moving object produced a large and predictable of the laser's output intensity. In company with many other laser experimentalist, the PIs at first deemed this observation as a chaotic nuisance effect to be avoided; further investigation showed that this effect can provide an extremely valuable alternative to complex, high-precision Michelson or MachZehnder or other types of interferometry. This new method, using only an inexpensive gas laser and the target, is particularly useful for the measurement of motions and displacements from microns down to picometers. The effect, named LAMDA (Laser Amplified Motion Detection and Analysis), is linear for changes in target position of less than 8 of the laser light wavelength and has been observed easily for motion as small as ~ 10 picometers. LAMDA requires only a small amount (106 - 0.1%) of back reflected light; this is easily obtained with diffuse scattering surfaces or from small changes of refractive index at dielectric boundaries. Although observed in the PI's laboratory with He-Ne lasers, the effect should be present for all continuous wave lasers including diode lasers. Being able to measure motion and displacement down to the picometer scale with the simplest of experimental arrangements, an inexpensive laser and the surface to be measured, opens a whole new range of motion and vibration analysis, imaging, optical metrology, and optical data-storage possibilities. 1 It is anticipated that LAMDA, when thoroughly understood and applied, will have an effect on many fields of scientific research and technology. For the past several months we have begun to characterize in detail the mechanism and provide a firm theoretical basis for this LAMDA effect. 2 To date, one of the most interesting applications of LAMDA that we have found so far is the possibility of using LAMDA's high z-resolution (picometers) as the basis for a light microscope having the ability to resolve finer detail than possible with normal Frauenhofer-diffraction limited microscope objectives (~200- 400nm). By utilizing the LAMDA effect in a scanning confocal microscope design, we hope to observe features of biological samples to a resolution of 10nm.
