In some examples, a laser-based ophthalmological surgical system (hereinafter “system”) includes a therapeutic radiation source configured to emit therapeutic radiation with a first wavelength. The system may also include a probe radiation source configured to emit probe radiation with a second wavelength different than the first wavelength. The system may also include one or more optical elements configured to direct the therapeutic radiation and the probe radiation into an eye of a patient and to collect reflected probe radiation from the eye of the patient. The reflected probe radiation may be indicative of an amount of therapeutic radiation exposure of the eye of the patient. The system may also include a photodetector configured to receive the reflected probe radiation from the one or more optical elements and to generate a photocurrent indicative of the amount of therapeutic radiation exposure of the eye of the patient.