Improvement of accuracy of interferometric measurement of wedge angle of plates

Improvement of the sensitivity of measurements in the formation of holographic interferograms of wedge plates

“…In this case, the complex amplitudes of the light waves recording hologram 9 of wedge plate 7 have the form (1) (2) where a 1 and a 2 are the real valued amplitudes of the reference and object waves, ξ = cosα/λ is the spatial frequency of the reference wave, a is the angle between the direction of wave propagation and the x axis, λ is the wavelength of the light source, ε 1 (x, y) and ε 2 (x, y) are phase distortions of the light waves due to aberra tions of the optical system, and ϕ(x, y) is the phase change of the object wave as a result of its passage through wedge plate 7. Analogously to [8], we can write phase change ϕ(x, y) in the form (3) where γ is the wedge angle and n w is the refractive index of the plate material. Expression (3) shows that phase ϕ(x, y) of the light wave varies linearly in the direction of the y axis.…”

“…The formation of a pair of interference images of a wedge shaped plate in lateral or reverse shear interfer ometry makes it possible to reduce the measurement error by doubling the number of interference fringes in the plate images [7,8]. To reduce the measurement error for the wedge angle, it is necessary to use special approaches ensuring a decrease in the sensitivity of the interferometer to external vibrations [9] and eliminating the systematic component in the error associated with aberration of the optical part of the instrument [8].…”

“…To reduce the measurement error for the wedge angle, it is necessary to use special approaches ensuring a decrease in the sensitivity of the interferometer to external vibrations [9] and eliminating the systematic component in the error associated with aberration of the optical part of the instrument [8].…”

Reduction of the error in measuring the wedge angle of transparent plates in holographic reverse-shearing interferometry

“…Since the phases in the expressions for the illumi nances in interference patterns (11) are opposite each other, according to [11,12], one can use successive tuning of fringes in the right and left interferograms to obtain an infinitely wide fringe.…”

“…In the lateral shear interferometry, this can be done by forming a pair of separate interferograms of a wedge shaped plate and successive retuning fringes in each interferogram to an infinitely wide fringe [11,12].…”