A new method for recording holograms using incoherent light is described. The method is based on optical propagation through birefringent crystals. Optical methods for the reconstruction of such a hologram are also presented.
In this paper we present a scheme for the acquisition of high temporal resolution images of single particles with enhanced lateral localization accuracy. The scheme, which is implementable as a part of the illumination system of a standard confocal microscope, is based on the generation of a vector beam that is manipulated by polarimetry techniques to create a set of illumination PSFs with different spatial profiles. The combination of data collected in different illumination states enables the extraction of spatial information obscured by diffraction in the standard imaging system. An implementation of the scheme based on the utilization of the unique phenomenon of conical diffraction is presented, and the basic strategy it provides for enhanced localization in the diffraction limited region is demonstrated.
We present a method for removing the conjugate image in an incoherent-light holographic technique, namely, on-axis conoscopic holography. The point-spread function that we obtain is that of a complex Gabor zone pattern, which thus should allow good-quality reconstructions of objects. Experimental results are also presented, which confirm the validity of this method.Conoscopic holography is a recent incoherent-light holographic technique first presented in 1985 (Ref. 1) that is based on the propagation of light in a birefringent medium. The basic setup is shown in Fig. 1: a uniaxial crystal (C) is sandwiched between two circular polarizers (P1, P2). A lens images the object-here a point source-into the system. When the monochromatic light from the image (S) of the point source passes through the crystal and the two polarizers, a Gabor zone pattern (GZP) is observed at the output; it is the result of the velocity disparity between the ordinary and the extraordinary waves in the crystal. This interference pattern can be recorded on a photographic plate and reconstructed optically' both coherently and incoherently. It can also, as in Ref. 2 and this Letter, be recorded on a CCD camera and digitized in a microcomputer for a numerical reconstruction of the image and the shape of the object. Such patterns thus are referred to as holograms.In the on-axis (or in-line) configuration, the crystal axis is parallel to the geometrical axis, Oz, of the system, and the point-spread function (PSF), say H +, is a real GZP plus a bias. For a complete object, the hologram is the incoherent superposition of the GZP of each point.The two major problems in the reconstruction of the original object are the bias and the conjugate image. The bias is a usual drawback of incoherent holography; this problem has been solved 2 ' 3 by inserting an electrically driven half-wave plate [a liquid-crystal light valve (LCLV)] after the first circular polarizer so as to change its handedess (e.g., from right to left handed), thus providing us with a second PSF, which we denote Hcg. By calculating numerically the difference between the holograms obtained with each impulse response, we obtain a real GZP without bias, Hc = H+ -Hc. These H-(xy) = COS[fr(Xwhere x and y are the coordinates in the recording plane and fr is the Fresnel parameter, a scale factor that depends on the distance between the point and the recording plane. The exact expression of fr can be found in Ref.4, but it is not needed here. It is well known that the cosine in Hc can be decomposed into two exponentials, corresponding to the virtual image and to the conjugate real image of the point, 5 which, from an algorithmic point of view, is due to the fact that the real GZP Hc has zeros in the Fourier domain, whereas a phase GZP has none. We address here the remaining problem, namely, the elimination of the conjugate image. The configurations used until now to remove it are (i) the quasi-complex configuration, 2 3 in which one of the polarizers is changed from circular to linear, whose...
These authors contributed equally to this work.We present a new technology for super-resolution fluorescence imaging, based on conical diffraction. Conical diffraction is a linear, singular phenomenon, taking place when a laser beam is diffracted through a biaxial crystal. We use conical diffraction in a thin biaxial crystal to generate illumination patterns that are more compact than the classical Gaussian beam, and use them to generate a super-resolution imaging modality.While there already exist several super-resolution modalities, our technology (biaxial super-resolution: BSR) is distinguished by the unique combination of several performance features. Using BSR super-resolution data are achieved using low light illumination significantly less than required for classical confocal imaging, which makes BSR ideal for live-cell, long-term time-lapse super-resolution imaging. Furthermore, no specific sample preparation is required, and any fluorophore can be used. Perhaps most exciting, improved resolution BSR-imaging resolution enhancement can be achieved with any type of objective no matter the magnification, numerical aperture, working distance, or the absence or presence of immersion medium.In this article, we present the first implementation of BSR modality on a commercial confocal microscope. We acquire and analyze validation data, showing high quality super-resolved images of biological objects, and demonstrate the wide applicability of the technology. We report live-cell super-resolution imaging over a long period, and show that the light dose required for super-resolution imaging is far below the threshold likely to generate phototoxicity.
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