With some systems, the flatbed moves down slightly as each strip of the image is being written onto the plate by an imaging beam. The mirror remains centered over the plate, but pivots left and right as it writes the full width of the line or strip. This is known as a movable flatbed platesetter.

With other flatbed systems, the plate bed does not move. This is known as a stationary flatbed platesetter. The imaging beam mirror, which remains centered over the plate, advances along the plate to write each line. Like the moving plate bed version, the mirror pivots left and right in order to write the full length of the line.

Since the imaging beam mirror on both types of systems remains centered and does not travel side to side (it pivots to project the laser beam left and right across the plate), the distance between the mirror and the plate changes as the mirror pivots. The distance the laser beam travels is shortest when the mirror is directly overhead and it is the longest when the laser is imaging the left and right edges of the plate. To ensure that the dot size and shape is not distorted across the width of the plate (due to the varying distance between the mirror and the plate), the laser is directed through a special lens that compensates for this.

The design of the flatbed unit allows for efficiency in plate handling and high production rates, but the imaging technique used with flatbed systems limits the width of the imaged area. Flatbed systems are most often used for imaging visible light plates.