Lateral　effect　photodiodes　sense　the　position　of　a　laser　beam　by　measuring　the　change　of　current　between　opposite　anodes　and　a　common　cathode.　They　either　require　a　bias　current　or　the　current　is　photogenerated.　In　either　case,　their　linearity　is　affected　by　the　non-uniformity　of　the　current　distribution　between　the　anodes.　We　here　propose　a　bias-free,　lateral　photo-diode,　which　consists　of　a　resistive　layer　forming　an　extended　Schottky　contact　to　an　intrinsic　semiconductor.　In　our　sensor,　the　photo-generated　carriers　do　not　diffuse　laterally.　Rather,　their　localization　under　the　laser-beam　results　in　a　reduction　of　the　barrier　height　due　to　image　force　effect.　An　open-circuit　voltage　appears　between　two　opposite　electrodes　that　is　linear　with　the　laser-beam　position.　A　tetra-lateral　configuration,　with　four　anodes　at　the　edges　of　a　square-shaped　sensor,　allows　sensing　in　two　dimensions.　(c)　2021　Elsevier　B.V.　All　rights　reserved.