Spatial filter

About: Spatial filter is a research topic. Over the lifetime, 6170 publications have been published within this topic receiving 100451 citations.

Dynamic holography using pixelated light modulators

Abstract: Dynamic holography using spatial light modulators is a very flexible technique that offers various new applications compared to static holography. We give an overview on the technical background of dynamic holography focusing on pixelated spatial light modulators and their technical restrictions, and we present a selection of the numerous applications of dynamic holography.

Fluctuations of a focused beam wave for atmospheric turbulence probing

Abstract: This paper demonstrates that a focused beam wave may be effectively used to probe the atmospheric turbulence. Unlike plane and spherical waves, the focused beam has two parameters, i.e., the beam size and the radius of curvature of phase front at the aperture which may be easily varied experimentally. General formulations for the amplitude and phase correlation functions and structure functions of a focused beam wave are given including the effects of wind velocity and time delay. The effects of the beam size and the focal length on the spectral and spatial filter functions and temporal frequency spectrum are examined in detail including the effects of separation, wind velocity, and time delay. Using these functions, procedures are shown to probe the form of the spectral density of the index of refraction, the structure constant, and the wind velocity along the path.

Single-molecule orientation measurements with a quadrated pupil

Abstract: This Letter presents a means of measuring the dipole orientation of a fluorescent, orientationally fixed single molecule, which uses a specially designed phase mask, termed a “quadrated pupil,” conjugate to the back focal plane of a conventional wide-field microscope. The method leverages the spatial anisotropy of the far-field emission pattern of a dipole emitter and makes this anisotropy amenable to quantitative analysis at the image plane. In comparison to older image-fitting techniques that infer orientation by matching simulations to defocused or excessively magnified images, the quadrated pupil approach is more robust to minor modeling discrepancies and optical aberrations. Precision of 1°–5° is achieved in proof-of-concept experiments for both azimuthal (φ) and polar (θ) angles without defocusing. Since the phase mask is implemented on a liquid-crystal spatial light modulator that may be deactivated without any mechanical perturbation of the sample or imaging system, the technique may be readily integrated into clear aperture imaging studies.

Optical pulse shaping with a grating pair

Abstract: A passive pulse-shaping system capable of producing optical pulses of arbitrary temporal profile on the subnansecond time scale is described and analyzed. The system uses a pair of gratings in a delay line and various filtering operations. An experimental investigation of the system is described, and several results are included.