Person: Vargas Balbuena, Javier
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First Name
Javier
Last Name
Vargas Balbuena
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Óptica
Area
Optica
Identifiers
7 results
Search Results
Now showing 1 - 7 of 7
Item Flexible calibration procedure for fringe projection profilometry(Optical Engineering, 2007) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier; Terrón López, M. JoséA novel calibration method for whole field three-dimensional shape measurement by means of fringe projection is presented. Standard calibration techniques, polynomial- and model-based, have practical limitations such as the difficulty of measuring large fields of view, the need to use precise z stages, and bad calibration results due to inaccurate calibration points. The proposed calibration procedure is a mixture of the two main standard techniques, sharing their benefits and avoiding their main problems. In the proposed method, an absolute phase is projected over marked planes placed at unknown positions. The corresponding absolute phase and marks positions are recovered for each plane location. Using Zhang's calibration method, internal camera parameters (also called intrinsic parameters) and the spatial position for each plane are computed. Later on, a polynomial fit of depth with respect to the phase is performed. To obtain the absolute position of an object point, the depth coordinate is obtained by means of the polynomial calibration and its absolute phase. Then the lateral coordinates are computed from the depth, the internal parameters, and the pixel coordinates of the imaged point. Experimental results comparing the proposed method with the standard polynomial- based calibration are shown, demonstrating the feasibility of the proposed technique.Item Non-uniformly polarized beams across their transverse profiles: an introductory study for undergraduate optics courses(European Journal of Physics, 2004) Piquero Sanz, Gemma María; Vargas Balbuena, JavierWe provide a simple theoretical study of beams non-uniformly polarized across their transverse sections which can be introduced in undergraduate optics courses. In order to generate such beams we propose to use a slightly convergent (or divergent) linearly and uniformly polarized beam impinging on an anisotropic uniaxial material with the beam propagation direction along the optic axis. Analytical expressions for the Jones vector, Stokes parameters, ellipticity and azimuth at each point of the transverse section, perpendicular to the propagation direction, are obtained at the output of this system. By means of these parameters a detailed description of the state of polarization across the transverse profile is given.Item Multiresolution approach based on projection matrices(Applied Optics, 2009) Quiroga Mellado, Juan Antonio; Vargas Balbuena, JavierActive triangulation measurement systems with a rigid geometric configuration are inappropriate tor scanning large objects with low measuring tolerances. The reason is that the ratio between the depth recovery error and the lateral extension is a constant that depends on the geometric setup. As a consequence, measuring large areas with low depth recovery error requires the use of multiresolution techniques. We propose a multiresolution technique based on a camera-projector system previously calibrated. The method consists of changing the camera or projector's parameters in order to increase the system depth sensitivity A subpixel retroprojection error in the self-calibration process and a decrease of approximately one order of magnitude in the depth recovery error can be achieved using the proposed method.Item Adaptive spatiotemporal structured light method for fast three-dimensional measurement(Optical Engineering, 2006) Quiroga Mellado, Juan Antonio; Crespo Vázquez, Daniel; Vargas Balbuena, Javier; Gómez Pedrero, José AntonioWe present a high-speed 3-D spatiotemporal shape measurement technique by means of structured light. Current methods use a constant number of images that do not take into account the available temporal continuity of the measured object. That is, they focus on acquiring and processing as quickly as possible a fixed number of images to solve for the correspondence problem and later obtain the 3-D shape by triangulation. The number of images used imposes the use of some spatial support. The major contribution of our research is a new spatiotemporal scheme that, depending on the object's movement, adaptively uses the maximum number of projected images consistent with the local temporal continuity, therefore solving the correspondence problem with the minimum possible spatial support for each position. This is achieved by the use of a hybrid color pattern composed of an analog sinusoidal periodic code in the red channel and a digital binary spatial code in the blue channel that is cyclically displaced. No subpixel calculation is used and it is possible to implement error correction strategies that make the method fast and reliable, enabling dynamic online 3-D measurement of objects in movement.Item Three-dimensional measurement of microchips using structured light techniques(Optical Engineering, 2008) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier; Koninckx, Thomas; Van Gool, LucThe industry dealing with microchip inspection requires fast, flexible, repeatable, and stable 3-D measuring systems. The typical devices used for this purpose are coordinate measurement machines (CMMs). These systems have limitations such as high cost, low measurement speed, and small quantity of measured 3-D points. Now optical techniques are beginning to replace the typical touch probes because of their noncontact nature, their full-field measurement capability, their high measurement density, as well as their low cost and high measurement speed. However, typical properties of microchip devices, which include a strongly spatially varying reflectance, make impossible the direct use of the classical optical 3-D measurement techniques. We present a 3-D measurement technique capable of optically measuring these devices using a camera-projector system. The proposed method improves the dynamic range of the imaging system through the use of a set of gray-code (GC) and phase- shift (PS) measures with different CCD integration times. A set of extended-range GC and PS images are obtained and used to acquire a dense 3-D measure of the object. We measure the 3-D shape of an integrated circuit and obtained satisfactory results.Item Novel multiresolution approach for an adaptive structured light system(Optical Engineering, 2008) Quiroga Mellado, Juan Antonio; Vargas Balbuena, Javier3-D triangulation measurement systems with a fixed geometrical configuration have practical limitations that make them inappropriate for a wide variety of applications. The reason is that the ratio between the depth recovery error and the lateral extension is a constant that depends on the geometrical setup. Therefore, with a fixed triangulation setup, there is a tradeoff between field of view and depth resolution. As a consequence, measuring large areas with low depth recovery error necessitates the use of multiresolution techniques. In this work, we propose a multiresolution technique based on a camera-projector system previously calibrated and a second auxiliary camera that can move freely. The method consists of making first a measurement with a large field of view (coarse measurement). Afterwards, the geometrical configuration of the 3-D rig is changed to acquire a small field of view (fine measurement) that is referred to the original reference system and calibration parameters by means of the auxiliary camera. Using this method, a multiresolution reconstruction is possible without any optimization, registration, or recalibration process. Experimental results, which show a decrease of approximately one order of magnitude in the depth recovery error between fine and coarse measures, demonstrate the feasibility of the proposed method.Item Defect inspection by an active 3D multiresolution technique(Ninth International Symposium On Laser Metrology, Pts 1 And 2, 2008) Quiroga Mellado, Juan Antonio; Vargas Balbuena, JavierReliable inspection of large surfaces with low depth recovery error is needed in a wide variety of industrial applications, for example in external defect inspection in aeronautical surfaces. Active triangulation measurement systems with a rigid geometrical configuration are inappropriate for scanning large objects with low measuring tolerances due to the fixed ratio between the depth recovery error and the lateral extension. Therefore, with a rigid triangulation setup, if we are interested in defect inspection over extended surfaces then we have to assume errors proportional to the field of view that can preclude a precise local defect measurement. This problem can be solved by the use of multiresolution techniques. In this work we demonstrate the application of an active triangulation multiresolution method for defect inspection of large aeronautical panels. The technique is based on a standard camera-projector system used together with a second auxiliary camera that can move freely. The result is a global measurement with a superposed local measurement without any optimization, explicit registration or recalibration process. The presented results show that the depth recovery error of the local measurement permits the local defects measurement together with a wide-area inspection.