A laser machining system comprises a laser configured to generate a laser output for forming a molten pool on a substrate, a nozzle configured to supply a growth material to the molten pool for depositing the material on the substrate, and an optical unit configured to capture a plurality of grayscale images comprising temperature data during the laser deposition process, wherein the grayscale images correspond to respective ones of a plurality of radiation beams with different desired wavelengths. Further, the laser machining system comprises an image-processing unit configured to process the grayscale images to retrieve the temperature data according to linear relationships between temperatures in the laser deposition process and the corresponding grayscales of the respective images. A laser machining method is also presented.