Talbot Sensor with Diffraction Grating Adaptation to Wavefront Aberrations

Abstract

The results obtained at simulating the functioning of an adaptive sensor based on the Talbot effect are reported. The input grating period was varied depending on the examined wavefront shape and provided the constant observation plane corresponding to the Talbot plane for a plane wave. Using the spherical and astigmatic wavefronts as an example, it is shown that this method can make the sensor measurement range several times wider, by retaining the original angular sensitivity. K e y w o r d s: wavefront, Talbot effect, wavefront sensor.

Effect of noise and pixel size on the wavefront generated by amplitude holograms

“…As one knows [11], a beamsplitter could be used for the wavefront correction in an indirect way, however additional calculation of the DOE image is needed. Lenses L4, L5 or L3, L5 are configured for a 4F system, where imaging is performed by the holographic Shack-Hartmann wavefront sensor [8,9]. The point spread function (PSF) of the aberrated wavefronts analysis and verification is allowed in the second channel containing beamsplitter BS, lens L7 and CCD2.…”

Aberration measurements by a Talbot wavefront sensor in the presence of intensity variations

“…where constant multipliers are not taken into account, G(x, y) stands for correlation function of optical field, {C n,m } are the Fourier coefficients associated with grating unit cell [22], W(f x , f y ) is spatial spectrum of aperture function, n, n 1 , m and m 1 are integers. Considering infinite beam aperture with δ-like spatial spectrum [11]:…”

“…As one can see, displacement measurement error strongly depends on the unit cell form that is defined by its Fourier coefficients {C n }. Therefore, let us consider amplitude cosine grating for which Fourier coefficients are expressed as [22]: C n ∼ {0.5, 1, 0.5}, where n = {−1, 0, 1}. In this case intensity distribution can be given as: Fig.…”