text: The Herriott cell first appeared in 1965 when Donald R. Herriott and Harry J. Schulte published Folded Optical Delay Lines while at Bell Laboratories. The Herriott cell is made up of two opposing spherical mirrors. A hole is machined into one of the mirrors to allow the input and output beams to enter and exit the cavity. Alternatively, the beam may exit through a hole in the opposite mirror. In this fashion the Herriott cell can support multiple light sources by providing multiple entrance and exit holes in either of the mirrors. Unlike the White cell, the number of traversals is controlled by adjusting the separation distance D between the two mirrors. This cell is also commonly used and has some advantages over the White cell:
  * It is simpler than the White cell with only two mirrors that are easier to position and less susceptible to mechanical disturbance of the cell
  * Can be more stable than the White cell
  However, the Herriot cell does not accept high numerical aperture beams. In addition, larger sized mirrors must be used when longer path lengths are needed.