Optical device for projecting a radiation beam onto a data carrier

Abstract From the Canadian patent

The invention relates to an optical reading device,for the read out of data carried by a reflecting support wherein, the source is a non-polarized laser of which the exit surface is reflective ; the optical noise due to the reflection of the incident wave at the support is partially suppressed by inserting between the last partially polarizing and/or birefractive element and the data carrier a quarter wavelength plate which optically decouples the incident wave and the return wave. The optical noise is thus limited to the beats between the incident wave and the return wave reflected a second time by the support.