An illustrative optical measurement device includes a light source configured to emit light pulses directed at a target. The optical measurement device further includes a detector configured to detect arrival times for photons of the light pulses after the photons are scattered by the target. The optical measurement device further includes a processing unit configured to generate, based on the arrival times of the photons at the detector, histogram data associated with the target. The processing unit is further configured to determine, based on the histogram data, an absolute optical property associated with the target. The processing unit is further configured to determine, based on the absolute optical property, a blood oxygenation level of the user, and perform an operation based on the blood oxygenation level.