Measurements of the temperature rise of a laser‐illuminated field emitter show that a tip temperature in excess of 1000 °K can be obtained with a focused laser beam of modest power, and that the temperature rise per unit irradiance varies approximately in inverse proportion to the radius of the focal spot. By measuring the irradiance of the central fringe in the Fraunhofer diffraction pattern of a field emitter in a focused laser beam, the profile of the field emitter is mapped without removing it from the vacuum tube. A calculation based on the observed shank profile, and taking into account diffraction in a simple approximation, predicts a peak temperature rise in good agreement with experiment. These findings have important practical applications in photofield emission.