Floating type magneto-optic disk reading head system having external semiconductor laser resonator operating at orthogonal two mode oscillations

Claim 1

A magneto-optic disk reading head system for reading data magneto-optically stored in a magneto-optic disk, comprising an orthogonal two mode oscillation type resonator formed by a predetermined effective cavity length and outputting a beat signal indicating said stored data, said resonator comprising a laser means including a semiconductor laser for emitting orthogonal two mode lights from one end thereof, a first polarization means provided to receive said incident lights, for polarizing said incident lights, said magneto-optic disk provided to receive said lights polarized by said first polarization means, for changing angles of said polarized lights in response to said data and for reflecting said angle changed polarized lights to said first polarization means to be further polarized thereat, said laser means passing said further polarized lights to another end of said laser means, a second polarization means provided to receive said lights passed through said laser means, for polarizing said passed lights, and a semi-transparent mirror means provided to receive said lights polarized at said second polarization means, for reflecting a part of said lights polarized at said second polarized means, said part of said lights includes said incident lights to said second polarization means to be further polarized thereat, and passing a beat light, said incident lights further polarized at said second polarization means being directed to and passing through said laser means, a distance between said magneto-optic disk and said semitransparent mirror means defining said effective cavity length, said resonator substantially resonating said orthogonal two mode lights therein, said beat light output from said semitransparent mirror means having a frequency defined by said effective cavity length and said angles changed at said magneto-optic disk.