A device and a method for monitoring a plane in space over an interval of time to create an image representing the time history of the plane in space. A line image sensor (2) captures a series of line images of the plane in space which are converted to digital information by an A/D converter (4) for storage in solid state memory (3). To product a time history image of the plane in space, the line images can be retrieved from the solid state memory (3) by a computer (7). The computer (7) displays the series of line images adjacent to each other to create the time history image. The present invention has a number of applications, including photo finish cameras.