Control of laser pointer radiation by means of tunable acousto-optic filter

• Acousto-optic filter controls optic parameters of commercial laser pointers.
• Optic parameters of the pointers depend on source of driving electric power.
• Heating of the lasers and discharge of electric batteries cause drift of wavelengths and intensities in the laser pointers.

We measured optical radiation parameters of commercial laser pointers controlled by stabilized external sources of electric power and also by autonomous built-in alkaline batteries slowly discharging during a continuous operation of the pointers. In particular, variations of optical intensity and wavelength of the radiation generated by the pointers at the wavelengths close to 405 nm and 650 nm were recorded by the acousto-optic method. We used for the purpose, a tunable acousto-optic filter based on tellurium dioxide single crystal. Light diffraction on ultrasound was provided in the crystal by a slow shear acoustic wave propagating at the angle 9° with respect to the axis [1 1 0] in the (11¯0) plane of the material. Dependences of the output intensity and the lasing wavelengths on time and driving voltage were recorded in the carried out experiments. We also examined drifts of the wavelengths and the intensities in case of stabilized external as well as discharging built-in sources of electrical power. When used with the built-in batteries, the violet pointer demonstrated drifts of the wavelengths up to 3.2 nm during the first 50 min of the laser operation. Similar measurements in the red pointer resulted in the drift about 0.35 nm. Advantages of the used acousto-optic method of the radiation control are briefly discussed in the paper.