The paper presents the results of the research and development the brightness amplifier excited by longitudinal capacitive discharge with a pulse repetition frequency (PRF) up to 24 kHz for using in systems with optical signal amplification. The amplification features of the active element were experimentally studied. The results of the use the designed brightness amplifier in the MOPA system and in the laser monitors (bistatic and monostatic) demonstrate the efficiency of the designed active element for an optical signal amplification. The effect of the vapor concentration in the medium on image brightness amplification characteristics was experimentally estimated. The concentration of the CuBr vapors should be lower to provide the optimal features of laser monitors. The difference between concentration provided maximum output power and optimal active optical system parameters reaches 25%–30%. The contrast of the images in the monostatic and bistatic laser monitors higher 90%. •CuBr brightness amplifier excited by longitudinal capacitive discharge was developed.•The effect of the vapor concentration in the medium on image brightness amplification characteristics was experimentally estimated.•The results of the use the designed brightness amplifier in the MOPA system and in the laser monitors (bistatic and monostatic) are presented.