Depth-resolved wavefront aberrations using a coherence-gated Shack-Hartmann wavefront sensor

Abstract

Abstract:In the present paper we investigate the possibility of narrowing the depth range of a physical Shack -Hartmann (SH) wavefront sensor (WFS) by using coherence gating. For the coherence gating, two low coherence interferometry (LCI) methods are evaluated and proof of principle configurations demonstrated: (i) a time domain LCI method based on phase shifting interferometry and (ii) a spectral domain LCI method, based on tuning a narrow band optical source. The two configurations are used to demonstrate each, the possibility of constructing a coherence gated (CG) SH/WFS. It is shown that these configurations produce spot patterns similar to those provided by a conventional SH/WFS. The two proof of principle configurations are also used to illustrate elimination of stray reflections in the interface optics which normally disturb the operation of conventional SH/WFSs. The speed and noise performance of the two CG-SH/WFS implementations are discussed.

Perspective: Wavefront shaping techniques for controlling multiple light scattering in biological tissues: Toward in vivo applications

“…For imaging a thick scattering tissue, on the other hand, a depth-resolved aberration measurement is required, which can be achieved by adapting conventional strategies for holography which must provide a reference arm to measure interferometric signals. For depth-selective aberration measurements, coherence gating has been the method of choice, 107,108 and the correction obtained using coherence gating has also been shown to be effective for multiphoton excitation in an OCT-multiphoton multimodal microscope. 109…”

Route to OCT from OFS at University of Kent

“…AOG has investigated the interference on a CCD array between multiple beamlet outputs by the lenslet array and a reference beam provided by the same optical source used to illuminate the target [70]. Due to the aberrations encountered by the beam towards and backwards from the target (in double pass configurations) or coming from the target only (in single pass configurations), the beamlets suffer various deflections on the CCD array.…”

Snapshot coherence-gated direct wavefront sensing for multi-photon microscopy

“…In this case, selecting only the light from the focal plane and rejecting the light reflected elsewhere along the optical path is a major challenge. Previous attempts solved this with coherence-gated wavefront-sensing methods [23][24][25] or a pinhole [26] to select light from a plane of interest. The former methods use a low-coherence interferometer with either temporal-or spectral modulation, similar to optical coherence tomography (OCT) [27], while the latter uses a pinhole to select a volume overlapping with the laser focus.…”