Patent ID: 6816263
Filing Date: 2004-11-09
Classification: G01J

Abstract:
An interferometric measurement apparatus for wavelength calibration, comprising:a laser light source (1) emitting light of at least one wavelength, a detector (2), an interferometer (3) which separates the light of the laser light source (1) into two sub-beams (4, 5)â€”a reference beam (4) and a measurement beam (5)â€”and combines the sub-beams (4, 5) again after at least one reflection at one reflection means (6, 7) each, wherein a path length difference between the reference beam (4) and measurement beam (5) defines a constant wavelength calibration distance (11), and at least one additional reflection means (8) placed in the beam path of the measurement beam (5), said additional reflection means (8) reflecting the measurement beam (5) at least largely in the opposite direction.