Revista Mexicana de Física 43, No. 2 {1997} 167-174 Tomographic phase-distribution edge enhancement with differences of parallel projections: a proposal G. RODRÍGUEZ-ZURITA AND R. PASTRANA-SÁNCHEZ' Benemérita Universidad A utónoma de Puebla Facultad de Ciencias Físico-Matemáticas Apartado postal 1152, 72000 Puebla, Pue., México Recibido el 11 de julio de 1996;aceptado el 16 de enero de 1997 AnSTRACT. The possibility for a method to enhance two-dimensional refractive-index distribu- tions by using difference of parallel projections and tomographic retrieval techniques is discussed and sorne examples are given. RESUMEN. Se plantea la posibilidad de un método capaz de proporcionar distribuciones bidimen- sionales de Índice de refracción con sus bordes realzados y basados en diferencias de proyecciones paralelas junto con técnicas de reconstrucción tomográficas. Se presentan también algunos ejem- plos numéricos. rAes, 42.30.W; 42.40.K; 06.20; 42.65.H l. INTRODUCCIÓN Sorne irnprovements in wave-front transient double-exposure with photorefractive crystals with irnpact in the field of interferornetric inspection of an object or a process have been recently reported [1,2]. The potential of transient double-exposure in this field has been recognized early in the study of differential aspects such as the velocity in fluids [3], or the rneasurernent of directional derivativcs of rigid phase distributions by inducing object changes like rigid translations [4]. But induced changes as rotations seem to have received little attention, if any, in spite of its direct connection with optical tomography. In optical tomography a refractive-index distribution f(x, y) within a region is to be found on the basis of emerging wave-frouts after they propagate through the object at known angles of projection cj;. At the detection stage, interferometric techniques have to be incorporatcd to allow phase extraction [5] and rcconstruction of the phase distribution can be carried out with appropriate algorithms [6J. Along this letter, a novel relatiou between transient storage and optical tomography is proposed on the basis of transient holographic double-exposure wave-front reconstruction of two wavc fronts with phase distributions <p(p,1» and <p(p, 1> + 2.1» emerging from a rotating object (each front recorded at slightly diffcrent projecting angles 1> and 1> + 6.cj;, *INAOE graduate student and scholarship from CONACyT