Quartz fiber dosimeter
![Display of quartz fiber dosimeter, in units of roentgen. Viewing is by holding the instrument towards an external light source and looking through the magnifying eyepiece.[1]](/Images/godic/202502/05/Dosimeter_ablesung2526.jpg")
![Gold leaf electroscope showing principle of fiber dosimeter. When ionizing radiation penetrates the inner gas of the electroscope, ions are created. Since the gold leaves are charged positive, the negative ions are attracted to it and neutralize some of the charge, thus causing the gold leaves to close together.](/Images/godic/202502/05/Electroscope_showing_induction2526.png")
A quartz fiber dosimeter, sometimes called a self indicating pocket dosimeter (SIPD) or self reading pocket dosimeter (SRPD), is a type of radiation dosimeter, a pen-like device that measures the cumulative dose of ionizing radiation received by the device. It is usually clipped to a person's clothing and worn to measure one's actual exposure to radiation.