White-light spectral interferometry with the uncompensated Michelson interferometer and the group refractive index dispersion in fused silica

Spectral-domain tandem interferometry to measure the group dispersion of optical samples

“…(3) in which the path length difference ∆ M is replaced by the group OPD ∆ g M (λ). When the case of thick or strongly dispersive materials is considered, the spectral interference fringes have the largest period in the vicinity of a stationary phase point [4] for which the group OPD is zero at one specific wavelength λ 0 , which is referred to as the equalization wavelength [10] and which satisfies the relation…”

“…Taking into account the material of known dispersion such as fused silica [10] and the spectral range restricted to the wavelengths λ 0min = 450 nm and λ 0max = 900 nm, we obtain for ∆L Mmin = 100 µm, which corresponds to ten measurements with a 10 µm step, the minimum thickness t min ≈ 3 mm.…”

“…The main limitation of the method is reached for thick or strongly dispersive materials because under such conditions the spectral interference fringes that are far from the stationary phase point become difficult to resolve. Using a lowresolution spectrometer [10], the measurement of the group refractive index dispersion of a given material is still possible in the vicinity of the stationary phase point if one moves it in successive steps to different wavelengths and repeats the measurement. We measured in this way the dispersion of differential group refractive index of pure silica beam splitter present in a Michelson interferometer [10].…”

“…Using a lowresolution spectrometer [10], the measurement of the group refractive index dispersion of a given material is still possible in the vicinity of the stationary phase point if one moves it in successive steps to different wavelengths and repeats the measurement. We measured in this way the dispersion of differential group refractive index of pure silica beam splitter present in a Michelson interferometer [10]. The modification of the technique has been used in measurement of the group dispersion of a quartz crystal inserted into a test arm of a Michelson [11] or Mach-Zehnder interferometer [12].…”

Direct measurement of group dispersion of optical components using white-light spectral interferometry

“…The main limitation of the method is reached for thick or strongly dispersive materials because under such conditions the spectral interference fringes that are far from the stationary-phase point become difficult to resolve. Fortunately, the measurement of the group refractive index dispersion of a given material is still possible in the vicinity of the stationary-phase point if one moves it in successive steps to different wavelengths [8] and repeats the measurement. The modification of the technique with a tandem configuration of a Michelson interferometer and a calcite crystal of known thickness has been used in measurement of the group birefringence dispersion [9].…”