sometimes used for radiation dosimetry and personal monitoring. Note the non-linear response at the far left toe and right shoulder of the curve. This process is carried out immediately after exposure, as opposed to regular film, which is developed afterwards and requires additional chemicals. Although fragile and relatively heavy, the glass used for photographic plates was of better optical quality than early transparent plastics and was, at first, less expensive. Most plates and films described as orthochromatic or isochromatic were practically insensitive to red, so the correct focus of red light was unimportant; a red window could be used to view the frame numbers on the paper.