Patent ID: 6014359
Filing Date: 2000-01-11
Classification: G11B

Abstract:
An optical head, comprising:a light-generating means which emits linearly polarized light;a lens which converges said light emitted from said light-generating means on a medium;a light-detecting means which receives said light reflected on said medium;a quarter-wave plate which is disposed between said light-generating means and said lens and rotates by .pi./2 radian a polarization direction of said linearly polarized light when going and returning through said quarter-wave plate;a polarizing diffractive element which is disposed between said light-generating means and said quarter-wave plate, said polarizing diffractive element transmitting said light travelling from said light-generating means to said quarter-wave plate and diffracting said light travelling from said quarter-wave plate to said light-generating means by using a difference in polarization direction; anda polarizing beam splitter which is disposed among said light-generating means, said light-detecting means and said polarizing diffractive element, said polarizing beam splitter directing said light from said light-generating means to said polarizing diffractive element and directing said light from said polarizing diffractive element to said light-detecting means by using a difference in polarization direction;wherein said light-detecting means receives said light diffracted by said polarizing diffractive element and said light transmitted through said polarizing diffractive element.