A system and method to automatically obtain spectra for samples. The method involves a two phase process including a photobleaching phase and a spectral acquisition phase. In the photobleaching phase, a series of spectral data sets of a sample are collected. A relative difference is determined between the background of subsequent spectral data sets is determined and compared to a predetermined threshold value. If threshold difference is less than the relative difference between the background of subsequent spectral data sets, the steps of collecting a series of spectra data sets is automatically repeated. In the spectrum acquisition phase, a series of Raman data sets of the sample are collected until a target SNR is obtained.