Abstract: A semiconductor photodetector (1) for detecting short duration laser light pulses of predetermined wavelength in a light signal (2) comprises a micro-resonator (3) of vertical Fabry-Perot construction having a Bragg mirror pair, namely, a front mirror (5) and a rear mirror (6) with an active region (8) located between the front and rear mirrors (5,6). An N-type substrate (11) supports the rear mirror (6). The light signal (2) is directed into the active region (8) through the front mirror (5) while a pump beam (17) is directed into the active region (8) at an end (18) thereof. The spacing between the front and rear mirrors (5,6) is such as to cause light of the predetermined wavelength to resonate between the mirrors (5,6).

Abstract: A DVD case (1) is of integral one-part moulded plastics construction. A retainer (15) has two opposed retainer parts (32) having lips (33) for engagement of a DVD at opposed sides of its central aperture. The DVD is released by the parts (32) being moved closer together. However there is no need for the user to press them directly. He or she simply presses a push-button (20) at the edge of the seat, causing the parts (32) to move together in a simple action caused by an integrally moulded release mechanism (16, 17).

Abstract: A DVD case (1) is of integral one-part moulded plastics construction. A retainer (15) has two opposed retainer parts (32) having lips (33) for engagement of a DVD at opposed sides of its central aperture. The DVD is released by the parts (32) being moved closer together. However there is no need for the user to press them directly. He or she simply presses a push-button (20) at the edge of the seat, causing the parts (32) to move together in a simple action caused by an integrally moulded release mechanism (16, 17).

Abstract: A CD case (1) has a drawer (4) which may be pulled out by a handle (9) for access to a CD. The drawer (4) can be easily inserted during production, and multiple drawers can be stacked in stable manner. A front wall (7) engages in a groove (26) in a drawer (4) stacked on top of it to provide stability. A CD is retained in a seat (13) by a retainer (14) having opposed gripping retainer elements (20). A CD is released by a user pressing a button (17), causing arm branches (21) to pull together because of configuration of a resilient anchorage (16).

Abstract: A case stores CDs in a drawer which slides out from between an upper cover and a lower cover. The drawer has a handle projecting forwardly from the covers and which can be easily gripped by a user. A CD retainer in the drawer has a lip which grips a CD by snap-fitting over a side edge of the central aperture of the CD. The grip is released by the user simply pressing a push button, causing longitudinal movement of the retainer because it is on an arm extending between the button and a resilient anchorage.

Abstract: A case (1) stores CDs in a drawer (2) which slides out from between an upper cover (10) and a lower cover (11). The drawer (2) has a handle (19) projecting forwardly from the covers (10, 11) and which can be easily gripped by a user. A CD retainer (21) in the drawer (2) has a lip (23) which grips a CD by snap-fitting over a side edge of the central aperture of the CD. The grip is released by the user simply pressing a push button (25), causing longitudinal movement of the retainer (21) because it is on an arm (24) extending between the button (25) and a resilient anchorage (26).

Abstract: A method for measuring the power of a lens, comprising the following steps:(a) providing an unobstructed collimated beam of light to an opto-electronic transducer,(b) sampling the beam with said opto-electronic transducer to produce an output signal representing the intensity of light across the width of said collimated beam of light,(c) converting the transducer output signal to digital form and loading the resulting digital signal into a computer memory,(d) inserting a lens into the path of said collimated beam of light,(e) repeating steps (b) and (c) with the lens thus inserted into said beam for at least one separation distance, L, between said lens and said transducer, and(f) calculating the power of said lens from the digital signals stored in the computer memory.

Abstract: An optical system, including a waveguide such as an optical fiber, in which optical signals are noninvasively coupled into the waveguide at any point along the length of the waveguide, is disclosed. This is achieved by coupling substantially constant intensity electromagnetic radiation into the waveguide, and then impinging upon the waveguide a directed beam of energy, such as electromagnetic radiation or heat, from an energy source. Alternatively, the waveguide is impinged upon by a combination of an energy beam and a stimulus, e.g., a temperature change. The energy beam, or energy beam and stimulus, induce at least partial absorption of the guided, substantially constant intensity electromagnetic radiation by radiation-absorbing material in the waveguide, to produce the desired optical signal.

Abstract: An optical system, e.g., an optical fiber communication system or an optical mass storage device, which includes a linearly birefringent polarization rotator useful in an optical isolator or optical circulator, is disclosed. The rotator, which compensates for the effects of linear birefringence and is substantially antireciprocal, includes two or more material regions which are capable of subjecting incident light to elliptic birefringences. However, the sign and/or magnitude of the linear, or the sign and/or magnitude of the circular, components of the elliptic birefringences differ from region to region. Moreover, the length of each region, except the first or last region, is substantially equal to one-half the birefringent period of the region. The length of the first or last region, by contrast, is substantially equal to one-quarter the birefringent period of the region.

Abstract: An optical system, e.g., an optical fiber communication system or an optical mass storage device, which includes a linearly birefringent polarization rotator useful in an optical isolator or optical circulator, is disclosed. The rotator, which compensates for the effects of linear birefringence and is substantially antireciprocal, includes two or more material regions which are capable of subjecting incident light to elliptic birefringences. However, the sign and/or magnitude of the linear, or the sign and/or magnitude of the circular, components of the elliptic birefringences differ from region to region. Moreover, the length of each region, except the first or last region, is substantially equal to one-half the birefringent period of the region. The length of the first or last region, by contrast, is substantially equal to one-quarter the birefringent period of the region.