An apparatus for determining a location of at least one object on a touch surface, said apparatus comprising: a panel defining the touch surface and an opposite surface; an illumination arrangement adapted to introduce at least two beams (B1-B6) of radiation into the panel for propagation by internal reflection between the touch surface and the opposite surface, and to sweep each beam (B1-B6) across the touch surface within a sensing area, whereby an object that touches the touch surface within the sensing area causes said at least two beams (B1-B6) to be temporarily attenuated; a detection arrangement for coupling said at least two beams (B1-B6) out of the panel as they are swept along one or more elongate outcoupling sites on the panel downstream of the sensing area, said detection arrangement comprising at least one light sensor (3; 3') which is optically coupled to said one or more elongate outcoupling sites and adapted to measure the received energy of the respective beam (B1-B6) within said one or more elongate outcoupling sites; and a data processor connected to the detection arrangement and configured to obtain output signals (S1, S2) indicative of the received energy of the respective beam (B1-B6) at different spatial locations within each of said one or more elongate outcoupling sites as a function of time and to identify the location of the object based on the output signals (S1, S2), characterized in that said at least two beams (B1-B6) comprise a first set of mutually acute beams (B1, B2, B4), and that the illumination arrangement is configured to sweep the first set of mutually acute beams (B1, B2, B4) in a first principal direction that is essentially parallel to an edge of the panel, wherein the beams (B1, B2, B4) in the first set have a maximum mutual acute angle of ≤30°, and preferably ≤20°. a panel defining the touch surface and an opposite surface; an illumination arrangement adapted to introduce at least two beams (B1-B6) of radiation into the panel for propagation by internal reflection between the touch surface and the opposite surface, and to sweep each beam (B1-B6) across the touch surface within a sensing area, whereby an object that touches the touch surface within the sensing area causes said at least two beams (B1-B6) to be temporarily attenuated; a detection arrangement for coupling said at least two beams (B1-B6) out of the panel as they are swept along one or more elongate outcoupling sites on the panel downstream of the sensing area, said detection arrangement comprising at least one light sensor (3; 3') which is optically coupled to said one or more elongate outcoupling sites and adapted to measure the received energy of the respective beam (B1-B6) within said one or more elongate outcoupling sites; and a data processor connected to the detection arrangement and configured to obtain output signals (S1, S2) indicative of the received energy of the respective beam (B1-B6) at different spatial locations within each of said one or more elongate outcoupling sites as a function of time and to identify the location of the object based on the output signals (S1, S2), characterized in that said at least two beams (B1-B6) comprise a first set of mutually acute beams (B1, B2, B4), and that the illumination arrangement is configured to sweep the first set of mutually acute beams (B1, B2, B4) in a first principal direction that is essentially parallel to an edge of the panel, wherein the beams (B1, B2, B4) in the first set have a maximum mutual acute angle of ≤30°, and preferably ≤20°.