| 摘要 |
An apparatus (10) having a laser light source (12), an interferometer (13) with a dove prism/beamsplitter (14) and a retroreflector (16) for splitting a beam of light emitted by the laser diode into a second beam (54) and a third beam (54'), the third beam (54') having a light path through the retroreflector (16) with a variable length, and for recombining the second beam (54) with the third beam (54'), a translation stage (18) driven by a stepper motor (30) for varying the length of the light path, a lens (28) for directing the recombined second beam and third beam (48) to an object (52) to be measured so that the reflected second beam and third beam (48) interfere, a photocell detector (24) for converting an interference fringe pattern to a signal, a noise canceller circuit (50) for subtracting the light source noise from the signal and a computer (34) for controlling the stepper motor (30) and for plotting the signal against the length of the light path. |
