Pseudocoloring method for 3-D contouring

The interference properties of white light speckle pattern obtained with an optical system not corrected for chromatic aberration are applied to pseudocolor encode the depth level contours of a 3-D diffusing object. At a first step, a recording of the different encoded images of depth levels is done. In a second step, a reconstructed pseudocolored image is obtained, where different color assignements can be tuned by changing the position of a spatial filter slit. Also, a quantitative contouring can be made scanning the pseudocolored image plane with a spectroscopic device

A speckle method of gray level pseudocoloring

A simple method of pseudocoloring gray level images is proposed. It is based on Young’s fringes modulated speckle encoding of images. Reconstruction from a photographic register is obtained using two light beams with different wavelengths at the same time. Pseudocoloring is produced by the superposition of a (diffracted) direct image in one color and a (directly transmitted) contrast reversed image in another color

Color storage and image processing through Young's fringes modulated speckle

Young's fringes modulated speckle (YFMS) can be used for storing several pictures in a single photographic plate. In this Letter we present a simple application of this technique for color storage on black and white film, which allows information processing in different colors in an independent way

Optical image subtraction through speckle modulated by young fringes

A new method for subtracting images is proposed. It is based on assigning complementary Young's fringes to the speckles of the common parts of two images. In this way, carrier frequency is cancelled, and “a-posteriori” spatial filtering shows only noncommon parts. Suggestions on applications of the method are briefly commented

Quality parameters analysis of optical imaging systems with enhanced focal depth using the Wigner distribution function

An analysis of the Strehl ratio and the optical transfer function as imaging quality parameters of optical elements with enhanced focal length is carried out by employing the Wigner distribution function. To this end, we use four different pupil functions: a full circular aperture, a hyper-Gaussian aperture, a quartic phase plate, and a logarithmic phase mask. A comparison is performed between the quality parameters and test images formed by these pupil functions at different defocus distances

In-plane motion measurements with Fourier lensless holography

A holographic and moire technique for measuring inplane motions of a holographic plate attached to an object is described. This one seems easier to implement than a similar approach given by Roychoudhuri and Machorro. It is well known that when spherical and plane coherent wave fronts interfere, they give rise to a Fresnel-zonelike interference pattern. This is so when a lensless Fourier hologram of an empty pupil is recorded.If between two such exposures the holographic plate is rotated or translated inplane, the two overlapping interference patterns will produce low-frequency moire patterns. If the displacement involved is small (less than the innermost Fresnel ring), the moire pattern consists of equally spaced straight lines perpendicular to the direction of the displacement.a and the interfringe spacing is inversely proportional to the magnitude of the displacement

Walsh functions: analysis of their properties under Fresnel diffraction

The free-propagation properties of the light field diffracted by an aperture, have been investigated by employing a formalism based on the orthogonal and complete set of Walsh functions. We found an interesting link with the well-known self-imaging phenomenon, which can be used to explain the spatial filtering properties of many optical devices. An experimental result is given in order to illustrate this approach

Rigid body motion measurements with Fourier lensless holography

A recently proposed holographic and moiré technique for in-plane motion measurements is generalized to certain cases of rigid body motion measurements

Surface roughness measurement through a speckle method

An optical approach for real-time measurement of statistical parameters associated with rough surfaces is proposed. Two crossed polarized, partially correlated, speckle patterns originated from a surface under different illumination conditions arc recorded on a linear photodiode array. The r.m.s. surface roughness is related to the correlation degree between both speckle patterns, which in turn is derived by processing the detected intensity distribution. Some experimental results are shown in order to illustrate this technique

Real-time white light pseudocolor density encoder

A simple method for pseudocolor encoding of gray level information is proposed. It is based on the real-time addition of the positive and negative images of an object transparency, each one obtained in a different color. Conventional white light lamps with adequate color filters are used. Some experimental results are shown