The intensity of solar illu minance was measured with a light meter, the measured illuminance was converted to insolation using a coefficient.

• 用照度计测量太阳光的照度，通过比较日 本气象厅在广岛市测得的瞬时日射量和相同时刻所测得的照度，计算出转换系数，然后估算 出照射在牙釉质样品的累积日射量。