Bradley Wade Schilling

Three-dimensional microscopy by optical scanning holography

We first briefly review a new 3-D imaging technique called optical scanning holography (OSH). We then discuss the techniques 3-D holographic magnification in the context of optical scanning and digital reconstruction. Finally, we demonstrate the 3-D imaging capability of OSH by holographically recording two planar objects at different depths and reconstructing the hologram digitally.

Three-dimensional holographic fluorescence microscope

Most commonly used methods for three-dimensional (3D) fluorescence microscopy make use of sectioning techniques that require that the object be physically scanned in a series of two-dimensional (2D) sections along the z axis. The main drawback in these approaches is the need for these sequential 2D scans. An alternative approach to fluorescence imaging in three dimensions has been developed that is based on optical scanning holography. This novel approach requires only a 2D scan to record 3D information. Holograms of 15-microm fluorescent latex beads with longitinal separation of ~2 mm have been recorded and reconstructed. To our knowledge, this is the first time holograms of fluorescent specimens have been recorded by an optical holographic technique.

Twin-image elimination experiments for three-dimensional images in optical scanning holography

Twin-image elimination in the context of optical scanning holography has recently been proposed. The proposed technique involves simultaneously acquiring sine and cosine Fresnel holograms. A complex hologram is then formed by complex addition of the holograms, and twin-image rejection is predicted by computer simulations. An experimental verification of the technique by optical acquisition of the two holograms and subsequent reconstruction of the complex hologram digitally is reported. Three-dimensional image reconstruction without twin-image noise is demonstrated.

Real-time two-dimensional holographic imaging by using an electron-beam-addressed spatial light modulator.

A real-time electron-beam-addressed spatial light modulator-based holographic imaging system has recently been proposed. We present results of two-dimensional holographic imaging and further demonstrate that the proposed system can be readily adaptable to automation by using digital computers for robust holographic imaging. Specifically, by nonlinear processing of a digitally stored hologram, fringe contrast enhancement has been achieved.

Three-dimensional location of fluorescent inhomogeneities in turbid media by scanning heterodyne holography

We describe and illustrate experimentally a method aimed at the three-dimensional (3-D) imaging of fluorescent inhomogeneities embedded in a turbid medium. The method utilizes incoherent scanning holography to capture 3-D information in a single two-dimensional scan and phase-sensitive heterodyne detection to reject multiply scattered light and to produce a single-sideband holographic record. The 3-D imaging capability of the method is illustrated by an example.

Real-time preprocessing of holographic information

Optical scanning holography (OSH) is a holographic recording technique that uses active optical heterodyne scanning to generate holographic information pertaining to an object. The holographic information manifests itself as an electrical signal suitable for real-time image reconstruction using a spatial light modulator. The electrical signal that carries the holographic information can also be digitized for computer storage and processing, allowing the image reconstruction to be performed numerically. In previous experiments with this technique, holographic information has been recorded using the interference pattern of a plane wave and a spherical wave of different temporal frequencies to scan an object. However, the proper manipulation of the pupil functions in the recording stage can result in real-time processing of the holographic information of an object during recording. We propose a holographic edge extraction technique as an important example of real-time preprocessing of holographic information that utilizes alternate pupils in the OSH recording stage. We investigate the theory of holographic preprocessing using a spatial frequency-domain analysis based on the recording systems optical transfer function. The theory is reinforced through computer simulation.

Optical scanning holographic microscopy

We first review a newly developed 3D imaging technique called optical scanning holography (OSH), and discuss recording and reconstruction of a point object using the principle of OSH. We then derive 3D holographic magnification, using three points configured as a 3D object. Finally, we demonstrated 3D imaging capability of OSH by holographically recording two planar objects at different depths and reconstructing the hologram digitally.

Advances in optical-scanning holography

Holographic information pertaining to an object can be generated using an active optical heterodyne scanning technique. In this technique, the holographic information manifests itself as an electrical signal which can be sent to an electron-beam-addressed spatial light modulator for coherent image reconstruction. Real-time holographic imaging of 2-D objects has recently been demonstrated. The use of alternate waveforms in the scanning beam can process the holographic content of the object in real time. In this communication, we propose a holographic edge extraction technique which utilizes alternate waveforms in the optical scanning holographic recording stage. We have developed a 1-D computer model of the optical heterodyne scanning holographic system using Fourier analysis which we use to simulate holographic edge extraction.