Radiation monitor. Sarax Systems RM2000 radiation monitor and dosimeter (dose meter). Dosimeters measure exposure to ionizing radiation. They are often used by people who are exposed to radiation regularly during their work. There are strict limits to the amount of radiation to which nuclear industry workers, and those working with radioactive materials in laboratories, can be exposed. Devices such as these help ensure the workers' exposure is kept within these limits. This device provides an indication of radiation exposure on its large analogue meter scale (not seen).