From Newport Corporation
This application note details a simple and cost effective solution for the continuous attenuation of laser output power. The attenuator kit described is based on a half waveplate and polarizer. It is suitable for attenuation of a linearly polarized laser beam with a wavelength in the 690 nm -1040 nm range and average power up to 100 watts.
The principle of operation is based on Malus' Law. The intensity I of the polarized light that passes through the polarizer is given by where I0 is the input intensity, and ??is the angle between the beam's initial direction of polarization and the axis of the polarizer. Rotation of a 1/2 wave-plate mounted to a rotational stage allows continuous rotation of the beam's polarization direction. When combined with a polarizer, it provides variable attenuation according to (1). Wave-plates are usually made of birefringent crystal cut parallel to the optical axis.
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Topics of Interest
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