Some implementations of the present disclosure provide a laser drilling tool assembly comprising: (i) a body that includes: a first segment configured to receive an input beam from a laser source and couple the input beam to provide an irradiation beam to irradiate a downhole target, and a second segment housing one or more purging pipes; and (ii) a tool head that includes: a retractable nozzle; and one or more optical sensing elements mounted on the retractable nozzle, wherein when the downhole target is being irradiated by the irradiation beam, the retractable nozzle is extended towards the downhole target such that the one or more optical sensing elements are positioned closer to the downhole target.