OBJECTIVE HEAD FOR FIBRESCOPES

Abstract: An objective head (15) for a fibrescope is fabricated by casting or moulding from optically clear plastic having lenses (22) integral with the head to form a single piece-structure. The invention includes the method of fabrication of such a fibrescope.

Description: OBJECTIVE HEAD FOR FIBRESCOPES The present invention relates to fibrescopes useful in medical, veterinary and industrial applications using bundles of optical fibres to illuminate and to transmit images of remotely located objects. Because of the nature of glass fibres (numerical aperture), it is frequently necessary to utilize a lens or lens system at the distal or objective end of light guide and imaging fibre optic bundles. In prior art fibrescopes the various light guide and imaging bundles are received and anchored within a metallic element known as an objective head. The metallic head is machined to provide recesses and appropriate through bores to accommodate fibre bundles and to provide outlets for the usual utility channels such as for air, water, suction and biopsy instruments. The required lenses, usually of glass, are individually manufactured at relatively high cost because of their small size; they are usually 1 to 2 mm. in diameter by .75 to 1.0 mm. thick. These small glass objects are cemented into machined counterbores in the metallic head. A representative example of the prior art is disclosed in U.S. Patent No. 4,266,534 issued on May 12, 1981. In this disclosure a variety of lenses 6 are shown cemented to machined counterbores in a metallic objective head. Such prior art heads suffer from a number of problems. One problem is the risk and the dangerous consequences of a lens falling out of its setting and detaching from the instrument during a critical medical, veterinary or industrial procedure. Another problem is the expense of manufacture. A further problem is ability of the prior art head to conduct electricity. Since various electrical power sources are frequently associated with modern fibre scopes, it has become necessary to provide electrical earths to insure against injury resulting from random or stray currents transmitted through a metallic head. It is an object of the present invention to provide an improved objective head structure which avoids the above disadvantages. According to one aspect of the present invention we provide an objective head for an image-transmitting fibrescope useful in medical, veterinary and industrial applications of the type having at the distal or objective end an objective head having recesses for receiving image and lighting fibre optic bundles and outlets for utility channels such as for air, irrigation, suction and hiopsy instruments characterised in that it comprises an optically clear plastic structure having at least one recess for receiving and anchoring at least one light guide fibre optic bundle and/or at least one imaging fibre optic bundle and at least one lens associated with the or each recess and the# or each fibre optic bundle received therein, the lenses and the head being an integral single piece structure. The invention includes fibrescopes incorporating an objective head as defined above. According to another aspect of the present invention we provide a method of producing an objective head for a fibrescope, said head having at least one recess for receiving a fibre optic bundle comprising the steps of: providing a mould in the desired configuration of the head, placing a core in the mould so that a bottom wall of said recess defines a lens shape, moulding the head using optically clear plastic material, and removing the core from tne moulded head thereby creating a moulded plastic objective head with the lens and the head being an integral single piece structure. Reference is now made to the accompanying drawings, in which: Figure 1 is a schematic representation of part of a prior art objective head; Figure 2 is a schematic view of an end face of an objective head of the present invention; Figure 3 is a sectional view along the line 3-3 of Figure 2; and Figure 4 is a sectional view along the line 4-4 of Figure 2. Referring to Figure 1 of the drawings, which is a fragmentary view of a prior art device, a machined metallic sleeve 10 is formed with a bore 11 for receiving a fibre optic bundle 12. A machined recess or counterbore 13 provides a receptacle or setting for a lens 14 fabricated as a separate piece-structure and cemented in place. In contrast an objective head according to the present invention is shown in Figures 2, 3 and 4. A generally cylindrical unitary objective head indicated generally by the reference numeral 15 is moulded or cast from an optically clear plastic material, preferably a polycarbonate resin. Other suitable resins include acrylics and urethanes. The objective head 15 includes a body 20 including a through bore 16 which communicates with a channel within a flexible shaft 17 of a fibrescope in well-known fashion. The bore 16 provides a conduit which can, for example, be used for a biopsy instrument and can be switched selectively to a source of suction. A bore 18 can communicate with a source of water and air in a usual and customary manner. The bores 19-19 receive and anchor fibre optic bundles (not shown) serving as light guides providing illumination at the face 21 of the head 15, the light being spread over the field of view of the imaging system by light guide lenses 22-22. The lenses 22-22 are moulded or cast integrally with the body 20 so as to form a single piece-structure. These lenses 22-22 also serve as a seal protecting the light guide fibre optic bundles. As can be seen in Figure 4 the bore 18 has a rounded protuberance or projection 23 extending slightly beyond the face of the objective head. This protuberance 23 affords a means for directing air or water in a predetermined direction across the face 21 of the objective head. Air or water, as the case may be, is directed in a predetermined direction by forming one or more orifices such as orifice 24 (Figure 4) in an appropriate location in the protuberance 23. The protuberance 23 is moulded integrally and forms a single piece-structure with the lenses 22-22 and the body 20. The image fibre optic bundle received in channel 15 (Figure 4) is also provided with an integral lens 25. Thus all fibre optic bundles are provided with a safe, cement-f ree lens and a liquid-tight seal protecting the fibre optic bundles from moisture arising from a medical, verterinary or industrial procedure or from sterilization. The objective head 15 may be formed or fabricated by preparing a mould cavity in the desired configuration, inserting in the mould a mould core to define the lens shape, injecting optically clear plastic material into the mould and after the plastic is set removing the core to provide a unitary objective head with "built-in" lens. If desired, the exterior of the head may be coated with a film of scratch-resistallt material such as Permalite or Duralite (both are trade names for organic silanes) to preserve the clarity of the plastic.

Claims: CLAIMS 1. An objective head for an image-transmitting fibrescope useful in medical, veterinary and industrial applications of the type having at the distal or objective end an objective head having recesses for receiving image and lighting fibre optic bundles and outlets for utility channels such as for air, irrigation, suction and biopsy instruments characterised in that it comprises an optically clear plastic structure having at least one recess for receiving and anchoring at least one light guide fibre optic bundle and/or at least one imaging fibre optic bundle and at least one lens associated with the or each recess and the or each fibre optic bundle received therein, the lenses and the head being an integral single piece structure. 2. An oDjective head according to Claim 1 in which the head is formed with at least one utility outlet operable to communicate with a utility channel in a fibrescope. 3. An objective head according to Claim 2 in which one utility channel outlet defines a bore open at one end and substantially closed at the opposite end by a protuberance which is an integral part of the head, said protuberance having an orifice located in a predetermined position effective to direct fluid passing through said bore across the face of said head. 4. An objective head according to any of Claims 1 to 3 moulded from polycarbonate resin. 5. An objective head according to any of Claims 1 to 4 having an exterior coating or transparent optically clear scratch-resistant material. 6. An image-transmitting fibrescope useful in medical, veterinary and industrial applications of the type having at the distal or objective end an objective head having recesses for receiving image and lighting fibre optic bundles and outlets for utility channels such as for air, irrigation, suction and biopsy instruments, characterised in that it has an objective head as claimed in any of Claims 1 to 5. 7. A method of producing an objective head for a fibrescope, said head having at least one recess for receiving a fibre optic bundle comprising the steps of: providing a mould in the desired configuration of the head, placing a core in the mould so that a bottom wall of said recess defines a lens shape, moulding the head using optically clear plastic material, and removing the core from the moulded head thereby creating a moulded plastic objective head with the lens and the head being an integral single piece structure. 8. A method according to Claim 7 including the addi- tional step of coating the exterior of the head with a skin or film of transparent optically clear scratch-res- istant material.

Inventors: CARPENTER, GEORGE J.
Applicants: WARNER-LAMBERT TECHNOLOGIES, INC.
Application year: 1985
Main classification: G02B23
IPC codes: G02B23, B29D11, A61B1