An apparatus and method are disclosed for examining optically a sample carried in a plurality of wells. A holder is adapted to receive and hold in place a sample carrier. A plurality of excitation means selectively introduce excitation towards a spatially limited portion of a sample carrier held in place by said holder. Detecting means receive and detect emission radiation coupled out from a light output window of a sample carrier held in place by said holder. Said detecting means is common to said excitation means and is configured to receive emission radiation from a plurality of different spatially limited portions of a sample carrier held in place by said holder.