LIGHT INTENSITY MEASURING DEVICE

PROBLEM TO BE SOLVED: To provide a light intensity measuring device capable of measuring intensity of light generated by interaction with an object in a larger dynamic range and with practical accuracy.SOLUTION: The light intensity measuring device includes an irradiation system, a measurement system and a dimmer filter. The irradiation system irradiates an object to be tested with irradiation light. The measurement system measures the intensity of the light generated by the interaction between the irradiation light and the object to be tested. The dimmer filter dims at least one of the irradiation light and the light generated by the interaction by a plurality of dimming rates different from each other. The measurement system counts photons configuring the light dimmed by the plurality of dimming rates respectively using a photon counter prior to measurement of the light, and obtains the intensity of the light generated by the interaction when dimming is not performed by the plurality of dimming rates or when the dimming is performed by the same dimming rate on the basis of a calibration value of the dimming rate obtained on the basis of a result of counting the photons.