GB2289138A

GB2289138A - Optical lens containing a reflective layer

Info

Publication number: GB2289138A
Application number: GB9408323A
Authority: GB
Inventors: Hirofumi Koyama
Original assignee: Thomson Consumer Electronics SA; Thomson Consumer Electronics Inc
Current assignee: Technicolor SA; Technicolor USA Inc
Priority date: 1994-04-27
Filing date: 1994-04-27
Publication date: 1995-11-08
Also published as: GB9408323D0

Abstract

A multiple light path apparatus, which may be used for a wireless optical A/V (audio and video) communication system, comprises at least one reflective layer RL within a lens which forms an entry or end portion for a beam waveguide said layer RL forming an angle with the optical axis of the lens. The lens may be formed by moulding. The beam waveguide may form a stud 2 for connection to an optical fibre OF, LED or photodiode or photodetector PD. Layer RL may be semi-reflective. <IMAGE>

Description

Multiple Light Path The present invention relates to an arrangement and a method for a multiple light path, which may be used for a wireless optical A/V (audio and video) communication system.

Background An optical link by IR (infrared) ray between a TV set and a camcorder, having an IR receiver and an IR transmitter in front of each other respectively, can be a wireless optical A/V (audio and video) communication system if the light power and divergence angle are properly set.

However , it is also required to have an extra optical link between the TV set and a video tape recorder which in most cases is placed apart from the location of the camcorder and placed near the TV set.

The extra optical link should be dust free because they are connected each other a long distance and it should be maintenance free, and therefore it is better to use a link by using an optical fiber.

In this case for the connection, it is necessary to have an extra photo diode or photo detector, in the following called PD, on the TV set and also an extra light emitting diode, in the following called LED, is required for the fiber, and this will result in a cost up for such a system.

Invention It is one object of the invention to provide a multiple light path arrangement, which may be used for transmission and /or receiving of a modulated optical signal into and/or from air and at least one optical fiber especially for a wireless optical A/V (audio and video) communication system.

This problem is solved as described in the claim 1,4 and 6.

More details are stated in subclaims.

In principle the inventive method consists in using a lens body for both transmission and/or receiving a modulated optical signal into and/or from air and an optical fiber or a so-called beam waveguid.

Therefore at least one small portion of a reflective layer is built into a lens body and forms the entry and/or end area for an optical fiber path. The reflective layer makes an angle with the direction of incoming or outgoing beams. Said reflective layer guides into the lens incoming ray into a beam waveguid stud or optical fiber sideways provided at lens. This stud is preferably manufactured from the material which has the same optical characteristics as the lens. The lens itself is preferably a plastic spherical lens having a levelled side, where may be arranged a LED or PD. To the optical fiber may be also arranged a LED or PD. By using a LED and PD with the modified lens, it is possible to have a multiple light path, namely for example , a LED can transmit ray into air and an optical fiber simultaneously and a PD can receive ray from air and an optical fiber simultaneously.

In principle it is also possible to built into a lens more than one reflective layer.

A dual light path arrangement may be manufa-ctured by low costs and used for both transmission and/or receiving of modulated optical signal into and/or from air and an optical fiber. In such a way the use of multiple light path apparatus advantageous lowers the costs for a wireless optical communication system.

Preferred embodiments The invention will now be described with reference to the accompanying drawings, in which: FIGURE 1 illustrates the basic construction of a dual light path arrangement.

FIGURE 2 shows schematically three views of a dual light path arrangement.

FIGURE 3 shows schematically a first practical application.

FIGURE 4 shows schematically a second practical application.

The basic construction of a dual light path element is illustrated in Fig. 1. Fig.1 shows a lens body LB having a convex surface 1 at one end and a levelled surface at the other end. This lens body LB also called a spherical lens contains inside a reflective layer RL and forms in connection with optical transmitters and receivers a multi light path arrangement.

The lens body LB is preferably a plastic spherical lens and the reflective layer RL is raised by a piece of flat metal. This layer RL may be also a semi reflective layer which is raised by a metal evaporation.

The reflective layer RL forms an angle with the optical axis of the lens.

The reflective layer was brought into the spherical lens during manufacture. At first a beam waveguid which may be made from the same material as the plastic spherical lens or from an optical fiber is bevelled as a bevel at the end which shall be raised within the lens. Then a reflective layer RL is applied to the bevel and afterwards this prepared end of the beam waveguide is brought into a mould in that the plastic spherical lens will be shaped. Thereby the optical axis of the beam waveguide is orthogonal arranged to the optical axis of the spherical lens and the prepared surface is angled aimed to convex side of lens. The beam waveguide forms a stud 2 which protrudes from the side of spherical lens. This stuck out end is at its end prepared for a connection with an optical fiber or direct coupled to a LED or PD. Therefore the end of stud 2 may be convex shaped and forms a second lens. The end of optical fiber may be also coupled to LED or PD.

The reflective layer on the beam waveguide within the lens changes the direction of an incoming and outgoing ray or light especial by reflection of ray from or to the levelled side of the spherical lens as shown in Figures 3 an 4. Due to the fact that the reflective layer changes the direction of ray from the stud 2 to the levelled side of spherical lens or from the levelled side of the spherical lens in the stud 2 this prepared spherical lens body may be used for a dual light path element within a dual light path arrangement.

The spherical lens has, as illustrated in Fig. 1, a focal point FP outside and in front of the levelled side of the spherical lens and Fig. 2 shows a top view, a side view (0) and a side view (90) of dual light path element The side view of Fig.2 illustrates that the studs is homogenous putted up within the spherical lens and the reflective layer within the spherical lens makes an optimum angle with the levelled side of the spherical lens The reflective layer extends from the surface at the side of spherical lens to near the centre. In order to shadow not ray incoming into the rod lens as the reflective layer a semi reflective layer preferably is used or shadow area is minimized by defining the diameter of stud 2.

The practical applications of dual light path element are shown in Fig.3 and Fig. 4. As Fig.3 illustrates a PD is arranged at the levelled side of modified spherical lens near the focus point and receives ray from both a first LED 1 and a second LED 2. The ray from the first LED 1 comes through air and the modified spherical lens and the ray from the second LED 2 comes through an optical fiber OF connected with stud 2. The stud 2 guides the ray to the reflective layer RL where the direction is changed and goes also to the PD. This arrangement provides a dual light path arrangement. Otherwise if the PD of Fig. 3 is replaced by a LED as shown in Fig. 4 the ray of the LED passes modified rod lens and air to a first PDl and a part of the emitted ray via the reflective layer stud 2 and optical fiber OF to the second PD 2. In such a way the modified spherical lens or dual light path element maybe used as multiple light path especially for a wireless optical communication system.

Claims

1. Multiple light path apparatus preferably for a wireless optical communication system characterized in that at least a reflective layer (RL) within a lens forms an entry or end portion for a beam waveguide said layer (RL) forming an angle with the optical axis of the lens.

2. Apparatus according to claim 1 characterized in that said reflective layer (RL) is a semi reflective layer or a small portion of full reflective layer.

3. Apparatus according to claim 1 characterized in that said lens is a plastic spherical lens having a levelled side coupled to an LED or PD.

4. Method for manufacturing a multiple light path apparatus characterized in that at least one beam waveguide is bevelled at the end which shall be raised within a lens said end of beam waveguide is coated by a reflective layer (RL) and said prepared end of beam waveguide will be brought into a mould in that said lens will be shaped for a multiple light path apparatus.

5. Method according to claim 4 characterized in that said beam waveguide is formed by the same material as the lens.

6. Method for using a multiple light path apparatus characterized in that said multiple light path apparatus is used for transmission and/or receiving of a modulated optical signal into and/or from air and at least one beam waveguid.