A system for sensing occlusions in an optical system, comprising: a first laser source configured to generate optical signals; a second laser source configured to generate optical signals; a set of optical elements (404, 406, 408, 410, 418, 420) arranged to receive the optical signals from the first laser source and to direct the optical signals along a beam path; a detector arranged to receive reflections of the optical signals travelling along at least a portion of the beam path; and a control system comprising a processor and memory storing executable instructions, the control system communicably coupled to the detector, wherein the instructions, when executed by the processor, enable the control system to: detect, based on signals generated by the detector, reflection signals associated with the reflections of the optical signals; and disable the second laser source based on detection of the reflection signals; characterised in that the system further comprises: a function generator communicably coupled to the first laser source, the function generator configured to generate a modulation signal to modulate the optical signals generated by the first laser source; and a lock-in amplifier communicably coupled to the detector, the function generator, and the control system, the lock-in amplifier configured to extract, based on the modulation signal, the reflection signals from the signals generated by the detector. a first laser source configured to generate optical signals; a second laser source configured to generate optical signals; a set of optical elements (404, 406, 408, 410, 418, 420) arranged to receive the optical signals from the first laser source and to direct the optical signals along a beam path; a detector arranged to receive reflections of the optical signals travelling along at least a portion of the beam path; and a control system comprising a processor and memory storing executable instructions, the control system communicably coupled to the detector, wherein the instructions, when executed by the processor, enable the control system to: detect, based on signals generated by the detector, reflection signals associated with the reflections of the optical signals; and disable the second laser source based on detection of the reflection signals; characterised in that the system further comprises: a function generator communicably coupled to the first laser source, the function generator configured to generate a modulation signal to modulate the optical signals generated by the first laser source; and a lock-in amplifier communicably coupled to the detector, the function generator, and the control system, the lock-in amplifier configured to extract, based on the modulation signal, the reflection signals from the signals generated by the detector. detect, based on signals generated by the detector, reflection signals associated with the reflections of the optical signals; and disable the second laser source based on detection of the reflection signals; characterised in that the system further comprises: a function generator communicably coupled to the first laser source, the function generator configured to generate a modulation signal to modulate the optical signals generated by the first laser source; and a lock-in amplifier communicably coupled to the detector, the function generator, and the control system, the lock-in amplifier configured to extract, based on the modulation signal, the reflection signals from the signals generated by the detector. a function generator communicably coupled to the first laser source, the function generator configured to generate a modulation signal to modulate the optical signals generated by the first laser source; and a lock-in amplifier communicably coupled to the detector, the function generator, and the control system, the lock-in amplifier configured to extract, based on the modulation signal, the reflection signals from the signals generated by the detector.