Measurement of absolute distance employing a tunable CW dye laser

With a CW dye laser acting as a tunable laser, the measurement of an absolute distance was demonstrated. A maximum tunable range was set for 34.99 nm (from 655.00 nm to 620.01 nm). To measure fractions, the heterodyne technique was used. The errors of the experimental results were within ±8.8 nm for distances between 0.1 and 10.1 mm