A mass spectrometer probe is formed of a nonconductive polymer that is doped with conductive material. The probe may be used as, or as part of, a repeller plate in a parallel laser ion desorption/ionization time-of-flight mass spectrometer. Transparent locations on the probe enable a sample placed thereon to be visualized before or during mass spectrometry. The conductive nature of the probe maintains the consistency of the electromagnetic field applied to the sample. The probe also displays low outgassing and high mechanical and chemical stability, thereby enabling it to be used repetitively.