Other

Jenkin A Richard

Barry G Broome

A read head optical system capable of reading either CD or DVD disks is provided. A monolithic molded hollow plastic block includes three lenses integrally molded into its exterior surfaces. A 780 nm laser diode is aligned with the first lens for reading CD disks, a 655 nm laser is aligned with the second lens for reading DVD disks and a detector for providing signal, focus and tracking data is aligned with the third molded lens. The hollow plastic block has an interior cavity adapted to support optical elements to receive and transmit the output of the laser diodes to the disks and to the detector. The three lenses are formed in the hollow plastic block in various embodiments.

Monolithic CD/DVD read/write head

An optical disk reader or read/write system for CD or DVD formats. First and second laser diodes operating at different wavelengths have their output beams collimated and directed at a single element objective lens, and are then reflected off the disk back through the lens to a photodetector. The single element objective lens has a central aperture zone and an outer aperture zone, the central zone being profiled to operate at a first numerical aperture at approximately 0.45 and the output beam of the first laser diode is confined to the central aperture zone. The outer aperture zone together with the central aperture zone are profiled to operate at a second numerical aperture, for example 0.60 wherein the output beam of the second laser diode has ray fans extending across the full aperture of the single element objective lens. A diffractive is formed on one surface of the single element objective lens and provides sufficient aspheric surface power for spherical aberration correction as well as correction for spherochromatism. The diffractive also provides sufficient correction for spherical aberration and spherochromatism that the single element objective lens achieves diffraction-limited image quality for both CD and DVD formats.

Single objective lens for use with CD or DVD optical disks

An optical communication device is provided. One or more pairs of matched diode lasers are located at first and second stations and are connected by a fiberoptic cable. A bit stream is applied to the output beam of the laser or lasers at the first station. The output beam carrying the bit stream passes through the fiberoptic cable to the matched laser or lasers at the second station and combine with the output beam of the receiving laser cavity at the second station to form a combined output beam. The power of the combined output beam is measured and time-dependent changes in the measured output power of the combined output beam is used to read the bit stream. Multiple pairs of matched lasers using different wavelengths may be positioned at the first and second stations. In yet another form of the invention, a frequency injection technique is utilized to modulate the output beam and a deconvolution system is provided to read the bit stream or streams.

Optical communication device

An optical sensing apparatus is provided for sensing changes of index of refraction and sensing changes of length of a fiberoptic cable, for example. A transmitting laser cavity produces a stable-resonator output beam which is modulated with a compound beam pattern including a first wave of frequency f.sub.1 and a second wave of frequency f.sub.2. The reflected compound modulated beam enters a receiving laser cavity and fundamental and harmonic waves f.sub.1 and f.sub.2 are generated in the receiving laser cavity. The power of the compound modulated output beam of the receiving laser cavity is measured by a photodiode and a deconvolution system is connected to the photodiode for filtering the fundamental frequency of f.sub.1 and the second harmonic of wave f.sub.2. Time-dependent changes in the measured power of the modulated compound output beam are used to derive changes of index of refraction or changes in length. In another form of the invention, two or more matched lasers form transmitting and receiving cavities and changes in the measured output power of the receiving cavity are used to derive the desired information.

Optical sensing apparatus

An apparatus and method are provided for determining the position of a reflective target surface using one or more laser cavities. A transmitting laser cavity produces a stable resonator output beam which is modulated with a compound beam pattern including a first wave of frequency f.sub.1 and a second wave of frequency f.sub.2. The reflected compound modulated beam enters a receiving laser cavity and fundamental and harmonic waves f.sub.1 and f.sub.2 are generated in the receiving laser cavity. The power of the compound modulated output beam of the receiving laser cavity is measured by a photodiode and a deconvolution system is connected to the photodiode for filtering the fundamental frequency of f.sub.1 and the second harmonic of wave f.sub.2. Time-dependent changes in the measured power of the modulated compound output beam are used to derive positional information of the target. In another form of the invention, two or more matched lasers form transmitting and receiving cavities and changes in the measured output power of the receiving cavity are used to derive positional information of the target. In another form of the invention, an amplitude modulated scheme is utilized wherein the coherence length of the output beam is reduced and time-dependent changes in the measured power of the modulated amplitude output beam in the receiving laser cavity are used to derive positional information of the target. [In another embodiment of the invention, a pair of matched diode lasers form the transmitting and receiving laser cavities, and wherein the output of the transmitting laser cavity is electronically modulated and wherein the impedance of the receiving diode laser is measured and time-dependent changes in the measured impedance are used to derive positional information of the target.]

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Berkeley, CA, United States of America

Jenkin A Richard