[en] A multipoint Thomson scattering system providing radial electron temperature and density profiles of plasma in a single shot is an on-line diagnostic on the spheromak device of CTX. The system includes a 22-joule, dual-beam ruby laser, large collection optics, and a spectrophotometer that contains a 40-mm dual chevron micro-channel-plate image intensifier tube as shutter and first stage of light amplification. A unique method of calibration that uses an 870-mm-long tungsten rod light source for instrument transmission and linearity measurements is described. Examples of data and temperature profiles are presented