NANOMETER-RESOLUTION DISTANCE MEASUREMENT WITH A NONINTERFEROMETRIC METHOD

We have developed a noninterferometric technique for high-resolution d istance measurement (optical ranging). The technique utilizes the fact that the wavelength of a broadband cw laser can be changed by externa l feedback. By placing the ranging target near the focal point of a mi croscope objective, we can make the feedback from the target, hence th e laser wavelength, sensitive to the target position. The target posit ion is determined from the laser wavelength with great resolution. In our experiments a 20-nm resolution is obtained. The resolution is limi ted by the instrumental resolution and mechanical stability of the exp erimental setup.