Image distortion due to refraction by planar surfaces

Ciencia y tecnología de buques, 2013

This article presents the design and implementation of a novel method to generate 3D coordinates from the projection of a laser line over a solid object and the processing of the images obtained during scanning. The result obtained is a 3D model of an isometric view that provides the possibility of being seen from different perspectives under a virtual environment. The methodology is applied in the capture and reconstruction of 3D images of objects submerged in murky waters.

2015

Underwater objects behind a refractive surface pose problems for traditional 3D reconstruction techniques. Scenes where underwater objects are visible from the surface are commonplace, however the refraction of light causes 3D points in these scenes to project non-linearly. Refractive Stereo Ray Tracing allows for accurate reconstruction by modeling the refraction of light. Our approach uses techniques from ray tracing to compute the 3D position of points behind a refractive surface. This technique aims to reconstruct underwater structures in situations where access to the water is dangerous or cost prohibitive. Experimental results in real and synthetic scenes show this technique effectively handles refraction.

Progress In Electromagnetics Research M, 2016

The image produced by metamaterial slabs is discussed in a number of papers in terms of the electromagnetic field distribution. I this paper a procedure is proposed to efficiently calculate the image of an extended object placed behind a metamaterial slab as it will be seen by an observer-which can greatly differ from the image formed on the intensity map. The first step of the procedure retrieves the dispersion relation of a periodic metamaterial slab from the S-parameters calculated with full wave electromagnetic simulation of the unit cell. The second step of the procedure utilizes the retrieved dispersion relation in the Transfer Matrix Method to calculate the image of a point source placed behind the metamaterial slab as a function of the observation angle. Knowing the image distance of the point source for all observation angles, the image of an extended object can be efficiently calculated. The procedure is demonstrated with a Fishnet type metamaterial.

Applied Optics, 2008

The paraxial theory of spherical refracting surfaces, spherical lenses, and slabs with one birefringent medium is investigated analytically: using walk-off effects in the paraxial domain, a number of relations between objects and images are deduced, along with cardinal elements, in the case where the optic axis is parallel to the optical axis. This method naturally shows that in some cases first-order astigmatism appears. An argument based on the wavefront (and phase) transformation shows that any spherical birefringent thin lens is stigmatic in the paraxial domain, because the first-order astigmatisms due to the two surfaces of such a lens compensate each other. This is a priori not the case with thick birefringent lenses-but two such cases are detailed.

2ND INTERNATIONAL CONFERENCE ON ENGINEERING & SCIENCE

In spite of its transparency, the determination process for the properties of submersible object into water is a difficult task. One of these difficulties arises from the differences in refractive indices between two different mediums such as air and water which changes the visual appearance of the immersed object. Such difficulties will provide unprecise measurements and hence the need for analyzing and having a mathematical model for such situation is a critical need. This paper introduced seven mathematical models to simulate the properties of two bodies (floating and submersible objects) under the effect of light attenuation and refraction phenomena caused by differences in refractive indices between air and water. Results show an accuracy in describing object's properties in underwater environment for both floating and submersible used bodies. The proposed models gave a good indicator in detecting underwater object's properties with lowest values for Mean Square Error (MSE) which had been used here. The lowest value for MSE had been detected upon scaling factor followed by Magnification and object's length estimator at final.

Proceedings of The IEEE, 2000

Solid immersion microscopy, similar to liquid immersion microscopy, extends the diffraction limit by filling the object space with a high refractive index material, such as glass (index of refraction n = 1:5-2), sapphire (n 1:8), and semiconductor materials (n 3), which shrink the wavelength of light. But solid immersion technique can achieve significantly higher spatial resolution since the refractive indices of available solids can be much higher than those of liquids (n = 1:3-1:5). Besides high spatial resolution, solid immersion microscopy also possesses all the good properties of far-field imaging, such as high transmission efficiency and parallel imaging capability, which make it outstanding among beyond-the-diffraction-limit optical imaging techniques. In this paper, we discuss, from an experimental point of view, the resolution limit of solid immersion microscopy and the implementation of such technique in various applications.

Journal of the Optical Society of America A, 2005

The differential theory of diffraction of light by an arbitrary object described in spherical coordinates is developed. Expanding the fields on the basis of vector spherical harmonics, we reduce the Maxwell equations to an infinite first-order differential set. In view of the truncation required for numerical integration, correct factorization rules are derived to express the components of D in terms of the components of E, a process that extends the fast Fourier factorization to the basis of vector spherical harmonics. Numerical overflows and instabilities are avoided through the use of the S-matrix propagation algorithm for carrying out the numerical integration. The method can analyze any shape and/or material, dielectric or conducting. It is particularly simple when applied to rotationally symmetric objects.

Sensors

The development of a robust 3D imaging system for underwater applications is a crucial process in underwater imaging where the physical properties of the underwater environment make the implementation of such systems challenging. Calibration is an essential step in the application of such imaging systems and is performed to acquire the parameters of the image formation model and to enable 3D reconstruction. We present a novel calibration method for an underwater 3D imaging system comprising a pair of cameras, of a projector, and of a single glass interface that is shared between cameras and projector(s). The image formation model is based on the axial camera model. The proposed calibration uses a numerical optimization of a 3D cost function to determine all system parameters, thus avoiding the minimization of re-projection errors which require numerically solving a 12th order polynomial equation multiple times for each observed point. We also propose a novel stable approach to estim...

2017

Immersion objectives can focus light into a spot smaller than what is achievable in free space, thereby enhancing the spatial resolution for various applications such as microscopy, spectroscopy, and lithography. Despite the availability of advanced lens polishing techniques, hand-polishing is still required to manufacture the front lens of a high-end immersion objective, which poses major constraints for lens design. This limits the shape of the front lens to spherical. Therefore, several other lenses need to be cascaded to correct for spherical aberration, resulting in significant challenges for miniaturization and adding design complexity for different immersion liquids. Here, by using metasurfaces, we demonstrate liquid immersion meta-lenses free of spherical aberration at various design wavelengths in the visible spectrum. We report water and oil immersion meta-lenses of various numerical apertures (NA) up to 1.1 and show that their measured focal spot sizes are diffraction-lim...

2000

In computer graphics, it is often an advantage to calculate refractions directly, especially when the application is time-critical or when line graphics have to be displayed. We specify efficient formulas and parametric equations for the refraction on straight lines and planes. Furthermore, we develop a general theory of refractions, with reflections as a special case. In the plane case, all refracted rays are normal to a characteristic conic section. We investigate the relation of this conic section and the diacaustic curve. Using this, we can deduce properties of reciprocal refraction and a virtual object transformation that makes it possible to produce 2D-refraction images with additional depth information. In the three-dimensional case, we investigate the counter image of a straight line. It is a very special ruled surface of order four. This yields results on the order of the refrax of algebraic curves and on the shading of refracted polygons. Finally, we provide a formula for the diacaustic of a circle.