A tomography method, system and apparatus based on time-domain spectroscopy are provided. In the method, a light emitter is controlled to emit a pulse beam to scan a cross-section of an object to be measured and simultaneously a light sensor is used to detect the pulse beam passing through the object to be measured, so as to obtain time-domain pulse signals of locations in a scan path. The scanning and detecting steps are repeated after changing the scan angle, and the time-domain pulse signals of multiple angles of the cross-section are collected as a time data set. Multiple features are retrieved from the time-domain pulse signals by using kernels of a trained machine learning model, in which the machine learning model is trained with data sets and corresponding true images of multiple cross-sections, so as to learn the kernels for retrieving the features. The retrieved features are transformed into a spatial domain to reconstruct a tomographic image of the cross-section. |