Wavefront sensing for low-coherent sources through spatial coherence revival

Abstract

An interferometry based wavefront sensing scheme applicable to low-coherent light sources is proposed and demonstrated. Using a pair of cascaded Sagnac interferometers, spatial frequency multiplexed interference of three sheared copies of the wavefront is recorded. The independent vector gradients obtained are used to reconstruct the wavefront. We overcome the spatio-temporal coherence limitations of the light source through the choice of spatial and spectral distribution of the light source. A Gaussian spectral distribution enables the measurement of the phase gradient corresponding to the central wavelength. Introduction of aperture for controlling the spatial distribution of the extended light source, we revive the spatial coherence of the optical field at the detector plane. We revive the spatial coherence of the field for the set value of lateral shear to maintain the visibility of the interference at the detectable level. Validating the scheme through measurement of changes in wavefront as a function of a collimation lens position, we apply it to reconstruct the wavefront of a light beam passing through a pseudo random phase plate, an atmospheric turbulence simulator.

Simultaneous two-step phase-shifting lateral shearing interferometry for aspherical surface based on an orthogonal shear displacer

“…The phaseunder testing in the x-direction is solved according to the amount 2 d d = of the phase step obtained from equations (8) and (9). Similarly, the phase under testing in the y-direction can also be obtained according to equations (10) and (11). The phase-shifting amount is extracted based on the principle of GS algorithm, a twostep Schmidt orthogonalization process is carried out for the two filtered interferograms of equations (8) and (9), equations (10) and (11), which will not be described in detail.…”

“…Lateral shearing interferometry (LSI) technology has become an effective tool in wavefront measurement due to its unique advantage that it does not require an ideal reference wavefront [2][3][4][5][6][7][8]. In recent years, researchers have presented many types of LSI wavefront measurement methods and have also applied different technologies to LSI design [1,3,4,6,[8][9][10]. Among them, polarization phase-shifting technology is one of the most effective methods for improving accuracy in LSI, especially in terms of the spatial phase-shifting simultaneous acquisition, it shows the advantages of simplicity, reliability, and small errors [7,11,12].…”

Error correction analysis of wavefront testing in quadriwave lateral shearing interferometry

“…In wavefront measuring interferometry, lateral shear interferometry (LSI) is widely used to study wavefront aberration testing, mostly to characterize optical devices, and to evaluate laser beams [1][2][3]. QWLSI is a measurement method of based on the LSI, as a powerful technology for aspherical surface testing, the wavefront derivatives along four directions can simultaneously be measured, and it has an absolute advantage for evaluation of the high-precision wavefront distortion [4][5][6][7].…”