We present an interactive simulation software to help to teach and learn the holography concept. The education interface was developed in the Java platform. The Holographic Interface is a computer assisted learning that can be used in classrooms or for distance education. The binary holograms are numerically generated and reconstructed in the virtual optical laboratory. Several procedures are shown. The interface has been implemented with di↵erent options such as addition, subtraction, multiplexing and some properties of holography. Moreover, the software was designed to simultaneously visualize the 2D object, the generated hologram and the recovered image. We have taken into account the students’ suggestions in this version in Java.
We present an alternative optical method to estimate the temperature during the cooling process of a liquid using digital holographic interferometry (DHI). We make use of phase variations that are linked to variations in the refractive index and the temperature property of a liquid. In DHI, a hologram is first recorded using an object beam scattered from a rectangular container with a liquid at a certain reference temperature. A second hologram is then recorded when the temperature is decreased slightly. A phase difference between the two holograms indicates a temperature variation, and it is possible to obtain the temperature value at each small point of the sensed optical field. The relative phase map between the two object states is obtained simply and quickly through Fourier-transform method. Our experimental results reveal that the temperature values measured using this method and those obtained with a thermometer are consistent. We additionally show that it is possible to analyze the heat-loss process of a liquid sample in dynamic events using DHI.
Phase unwrapping is an intermediate step for interferogram analysis. A smooth phase associated with an
interferogram can be estimated using a curve mesh of functions. Each of these functions can be approximated
by a linear combination of basis functions. In some cases constraints are needed to solve the phase unwrapping
problem, for example, when estimated values never can be negative. In this work it is proposed a method for
phase unwrapping using a set of functions in a mesh which are lineal combinations of Chebyshev polynomials.
Results show good performance when applied to noisy and noiseless synthetic images.
The large number of projections needed for tomographic reconstruction makes prohibitive the use of algebraic methods for fast phase object reconstruction. However, for smooth and continuous phase objects, the reconstruction can be performed with few projections by using an algorithm that approximates the phase as a linear combination of gaussian basis functions. This work presents an accurate algebraic reconstruction of a flame temperature from two independent interferometers using a He-Ne laser (623.8nm).
Analysis of Interferometric Synthetic Aperture Radar (InSAR) phase–maps with large wide band is still a challenging problem that requires the development of robust methods. This paper presents a 2–D Continuous Wavelet Transform method for denoising InSAR phase-maps. Owing to its high directionality, sensitivity and anisotropy, multiresolution analysis with 2–D Continuous Wavelet Transform (2–D CWT) is potentially a useful tool to construct appropriate filtering algorithms for detecting and identifying images with specific features, transient information content, or other properties. The 2-D Gabor wavelets naturally model the phase fringes, which means that can properly reconstruct the image. We describe the theoretical basis of the proposed technique and some experimental results with real InSAR phase–maps. As can be verified the proposal is robust and effective.