Optically stimulated luminescence dating accuracy
The exposure to radioactive elements continues, and the minerals begin again storing free electrons in their structures.
If you can measure the rate of acquisition of the stored energy, you can figure out how long it has been since the exposure happened.
Two forms of luminescence dating are used by archaeologists to date events in the past: thermoluminescence (TL) or thermally stimulated luminescence (TSL), which measures energy emitted after an object has been exposed to temperatures between 400 and 500°C; and optically stimulated luminescence (OSL), which measures energy emitted after an object has been exposed to daylight.
In the same way, more or less, OSL (optically stimulated luminescence) dating measures the last time an object was exposed to sunlight.Materials of geological origin will have absorbed considerable quantities of radiation since their formation, so any human-caused exposure to heat or light will reset the luminescence clock considerably more recently than that since only the energy stored since the event will be recorded.The way you measure energy stored in an object that you expect has been exposed to heat or light in the past is to stimulate that object again and measure the amount of energy released.We have to be very careful not to expose the sediments to sunlight when we do this! It is necessary to use red light conditions in the laboratory because the luminescence signal is light sensitive, and red light does not re-set it.
Search for optically stimulated luminescence dating accuracy:
This energy is lodged in the imperfect lattices of the mineral's crystals.