In thermovisors of the "Rubin" series the thermograms are recorded on electrochemical paper ckhb-4 having low cost and providing higher documentation speed. Elements with nonlinear transfer function, used in the videochannel give linear dependence between the thermogram's optical density and the object temperature. Piece-linear approximators provide for linearization. In a new thermovisor model "Rubin-3" the infrared flow is interrupted during idle pass along the line, what is different from previously used modulation during operating pass. Digital data on the level and range of temperature count, and the frame number are put on the thermogram during operating pass.