Optical waveguides – With disengagable mechanical connector – Optical fiber/optical fiber cable termination structure
Reexamination Certificate
2002-05-07
2004-09-28
Nguyen, Khiem (Department: 2839)
Optical waveguides
With disengagable mechanical connector
Optical fiber/optical fiber cable termination structure
Reexamination Certificate
active
06796720
ABSTRACT:
The present invention relates to the coupling of electromagnetic, particularly laser, radiation into and out of optical fibres and other optical devices. More particularly, it relates to optical components of the type comprising a lens mounted at an end of an optical fibre for coupling the radiation into and out of the optical fibre.
In many applications electromagnetic, particularly laser, radiation is transmitted using an optical fibre and must therefore enter the fibre at one end and exit the fibre at the other end. There is therefore a need to couple the electromagnetic radiation into and out of the fibre, to allow the radiation to, for example, be transferred into or out of the optical fibre from or into, for example, a second optical fibre or other optical equipment such as a laser.
One problem with coupling radiation into and out of an optical fibre is that it is necessary to align the incident radiation with the end of the optical fibre with a high degree of accuracy in order to minimise energy losses. However, this accurate alignment can be difficult to achieve since, due to the small diameter of optical fibres, small errors in the positioning of the end of the optical fibre relative to the incident radiation can result in large energy losses during transmission.
To alleviate this problem it is known to use a lens to focus the incident radiation beam onto the end of the optical fibre. The lens effectively focuses the radiation onto the fibre end, and, conversely, collimates or focuses radiation exiting the fibre. The lens, in effect, magnifies the end of the optical fibre, thereby increasing its effective size and making alignment of the radiation and the end of the optical fibre easier. Such an arrangement is often referred to as an “expanded beam” arrangement.
The positioning of the lens relative to the fibre end in these arrangements is, as will be appreciated from the above, important. For example, both the axial distance between the lens and fibre, and the radial distance between the lens and fibre may need to be set accurately.
The relative positioning of the lens and fibre could be adjusted in use, by providing a suitably adjustable holder for the lens and fibre. However, the adjustments can be relatively complex and time-consuming, and it may not therefore be desirable to always have to perform them in use, particularly where frequent changes or disconnection and reconnection, etc., of optical fibres in use is required.
It is known therefore to provide optical components comprising a lens and optical fibre held in a fixed, pre-aligned relationship in a holder, typically a cylindrical tube, so as to avoid the need to repeatedly adjust the relative positions of the lens and fibre in use. These devices are typically known as lens “tubes” or lens “barrels”.
The lens tube holds the lens and optical fibre end in a fixed alignment, therefore avoiding the need to further adjust the relative positions of those components in use. The lens tube can thus be inserted in an optical connector for, for example, optically coupling the fibre to another fibre. The connector in this situation would usually be provided with means to adjust the position and orientation of the two lens tubes so that they can be accurately aligned with respect to each other, but there is no need to otherwise adjust the positions of the individual lenses and fibres.
It will be appreciated that it is necessary to ensure appropriate alignment between the lens and optical fibre in the lens tube, so as to, for example, reduce energy losses from any misalignment of the lens with respect to the end of the optical fibre. It can in particular be important to ensure correct alignment between the optical axis of the fibre and the optical axis of the lens, and the relative tilt between these axes.
There is therefore a need to manufacture lens tubes in which the lens and the optical fibre are aligned with a high degree of accuracy. Many known lens tubes address this by providing means within the lens tube to adjust the position and orientation of the lens within the lens tube during manufacture of the lens tube so that accurate alignment of the lens and optical fibre can be achieved. Such a conventional lens adjustment mechanism typically comprises a series of adjustment screws spaced circumferentially around the lens to allow adjustment of the position of the lens until accurate alignment is achieved.
However, the Applicants have recognised that with this known method of manufacturing lens tubes in which the position of the lens is adjusted, the size of the lens tube is constrained by the need to accommodate the lens adjustment mechanisms.
From a first aspect therefore, the present invention provides a method of constructing an optical component, the method comprising providing a holder having a throughbore, mounting a lens within the throughbore in a fixed relationship with respect to the holder, inserting an optical fibre into the throughbore, and adjusting the position of the optical fibre within the throughbore to align the optical fibre with respect to the lens.
In the present invention, when the lens “tube” is constructed, rather than adjusting the position of the lens to align the lens and optical fibre, it is the optical fibre that is adjusted, with the lens being held in a fixed position.
By adjusting the optical fibre, as opposed to the lens, a less bulky adjustment mechanism is required, as the optical fibre has a much smaller diameter than the lens. In this way, the present invention allows for a more compact construction of lens tube when compared to known lens tubes. This can reduce manufacturing costs and also allows for less bulky construction of devices and systems that use the lens tube, such as the optical connectors referred to above.
The present invention also extends to an optical component (lens “tube”) constructed in accordance with the present invention and thus from a further aspect, the present invention provides an optical component comprising a holder having a throughbore, a lens mounted in the throughbore in a fixed relationship with respect to the holder, an optical fibre mounted in the throughbore, and adjustment means for adjusting the position of the optical fibre within the throughbore to align the optical fibre with respect to the lens.
The type of lens used in the present invention is not critical and so any suitable form of lens may be used. It may, for example, be a standard lens as used in conventional lens tubes. Unlike in conventional lens tubes, however, during manufacture the lens is immediately fixed in position relative to the holder. This may be done by any suitable means. For example, one end of the throughbore can be sized to snugly receive the lens which may then be glued in place thus providing a permanently fixed relationship between the lens and the holder.
The type of optical fibre used with the present invention is again not critical. The optical fibre may therefore take any suitable form and may be of a known type.
The optical fibre should be adjusted appropriately to ensure suitable alignment with the lens (and preferably with the longitudinal and/or mechanical axis of the throughbore and/or of the holder). Thus preferably the axial distance between the lens and fibre end is or can be adjusted. The radial alignment between the lens and fibre is also or instead preferably adjustable, as is the relative tilt between the optical axis of the fibre and the optical axis of the lens (and/or the mechanical or longitudinal axis of the throughbore and/or holder). It is also preferably possible to be able to adjust the lateral alignment of the fibre with respect to the lens.
Most preferably, the fibre is able to be moved axially within the throughbore. This can help, for example, to achieve the desired focus with the lens. In another preferred embodiment, the fibre is able to be moved radially within the throughbore (with the holder's adjustment means therefore being capable of moving the fibre radially within the throughbore). Most preferably the fibre can be
IP Law Specialists, llc
Nguyen Khiem
Orzechowski Karen Lee
Point Source Limited
LandOfFree
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