BINOCULAR BENT-AXIS LOUPES

Abstract: Optical loupes comprise a frame (12) supporting two optical devices (2) each of which has an ocular (3) and an objective (4). The frame has side arms or stems (24) and a bridge (not shown) enabling the frame to be worn like a pair of spectacles whereby the optical devices are located immediately in front of the respective eyes of the viewer. The optical axis (4) of the ocular and the optical axis (42) of the objective intersect at an angle of about 135 DEG and a Schmidt prism (23) redirects light from the objective to the ocular in each case. A light source (30) is provided on said frame between said optical devices and provides a gradually diverging light beam to illuminate an object being reviewed. The optical axes of the respective objectives converge at said object being reviewed. The loupes allow the user to observe at a level below his/her normal line of sight whilst maintaining the head in an upright position.

Description: TITLE: BINOCULAR BENT-AXIS LOUPES This invention relates to binoculars or loupes and more particularly to loupes which allow a viewer to closely and conveniently observe an object which is being manipulated by the hands of the viewer below the normal level of eyesight. When performing surgery, for example, a surgeon relies on a high level of eye hand co-ordination, generally with a small margin for error and so to enhance the precision and accuracy of the surgery it is necessary to magnify the region of the operation. Operating optical microscopes which comprise optical devices mounted on fixed stands have been used by surgeons for this purpose. However the field of view of these microscopes is set at the beginning of an operation and is not easily reset if a surgeon needs to alter the field of view to gain a better perspective of the operation or of the operating region. It is also common for surgeons to wear small head mounted binoculars or loupes to magnify their field of view. However as the level of an operation is below the normal level of eyesight of the surgeon, the head of the surgeon must be inclined to enable him to watch and co-ordinate his hands. During long operations even a slight inclination of the head can overwork the muscles of the neck discomforting the surgeon and providing an additional unnecessary distraction. This problem is compounded by the weight of the head mounted loupes. To allow a surgeon to sit and concentrate in one position for a long length of time and reduce the stress on the muscles of the neck it is preferable that the head and neck of the surgeon be in an upright aligned position so that the surgeon's line of sight is straight ahead. However due to the level of an operation this position is not possible with existing loupes. Furthermore this problem is not exclusively confined to those in the surgical profession. In fact any person such as a jeweller who is using existing loupes and manipulating very small objects for any length of time will encounter the same problems associated with inclination of the head, as the surgeon. It Is an object of the present invention to provide an apparatus which allows person to view and co-ordinate his/her hands below the normal line of sight withou having to incline his/her head and also to allow the person to readily change th field of view being magnified. Accordingly the invention provides optical loupes comprising a pair of optical devices (2) mounted on a frame for attachment on the head of a user whereby each optical device is in proximity to a respective eye of the user, characterised in that, each said optical device has an ocular (3), and an objective (4) which defines a field of view, said ocular and objective each has an optical axis (4, 42), the optical axis (42) through the objective intersects with the optical axis (4) through the ocular in each case, and light transfer means (23) is located between said ocular and objective for redirecting light from the objective to the ocular whereby an object which appears in the field of view of the objective is capable of being viewed through the ocular. By providing an apparatus whereby the optical axes of the objective and ocular intersect rather than project co-linearly, the light path from an image below the normal line of sight can be projected through the objective and redirected through the ocular to the eye of the viewer while the viewer is looking straight ahead. This allows the viewer to observe an object below the normal line of sight without the need to incline his/her head. Furthermore as the apparatus, in use, is attached to the head of the viewer the field of view observed can be changed simply by the viewer moving the position of his/her head. The forgoing and other features objects and advantages of the present invention will become more apparent from the following description of a preferred embodiment in which; Figure 1 is a side elevational view of an embodiment of the apparatus in accordance with the invention, Figure 2 is a partial plan view of the embodiment shown in Figure 1 , Figure 3 is a sectional view of one of the optical devices through line 3-3 of Figure 2, and Figure 4 is a sectional view of a central light through line 4-4 of Figure 2. The apparatus 1 in accordance with the embodiment is shown as having two optic devices 2 each with an ocular 3 and an objective 4. The ocular 3 comprises metal tube 5 which contains ocular lenses 6, 7 and field lens 8. Metal tube 5 i slidably mounted within ocular housing 9. An eye guard or hood 10 is fitted to th proximal end of tube 5 and is held in position by thumb screw 11. An aluminum frame 12 is fastened to a support collar 13 of the ocular 3 by mean of a locking screw 14. The locking screw passes through an elongate hole 15 i the frame 12 which allows the ocular a limited amount of lateral movement on th frame. Prior to the tightening of the locking screw 14 the interpupillary distanc between the two optical devices can be set by moving the locking screw 14 withi the elongate hole 15. The ocular housing 9 is connected to plate assembly 16 which is in turn locked i position by locking nut 21 which allows for optical axis alignment. Attached to plat assembly 16 is objective mounting collar 17. A window 43 in tube 20 is provide to facilitate the optical axis alignment. The objective comprises objective lenses 18, 19 in the distal end of tube 20 whic is mounted in objective mounting collar 17. Objective cover 44 is screwed onto th distal end 20a of the tube 20 and is provided to reduce the amount of refracted ligh entering the objective. A further cover 22 is provided to enclose the optical pat within the optical device. To allow a viewer looking through the ocular to view an object below his norma level of sight without inclining his head the respective optical axis 4 through th ocular lens and the optical axis 42 through the objective lens intersect at an angl less then 180° and preferably greater than 90° and more preferably at an angle i the range 120° - 150°. In the preferred embodiment the angle of intersection i about 135°. To redirect light from the objective to the ocular a light redirection means in the form of a Schmidt prism 23 is provided. As discussed above the optical device 2 is mounted onto a frame 12 and i preferably used in pairs to provide binocular vision. To position and support th optical devices in proximity to the eyes of the viewer, stems 24 are connected to th frame 12 by mountings 25. The stems attach to the mountings by pivot screws 2 and are slidably adjustable within the mounting 25. In use the stems 24 exten from the frame 12 along each side of the head of the viewer towards and over th ears in a similar way to the stems or side arms of spectacles which support an position the spectacles on a user. The frame 12 also has a nose support or bridg (not shown) for supporting the frame on the nose of a viewer again in a simila manner to spectacles. While this embodiment relies on a spectacle frame type arrangement which in use positions and supports the optical devices in proximity to the eyes of the viewer, it would be appreciated by those skilled in the art that other similar attachment means could be used provided they allow the viewer to change the field of view through the objective by movement of the position of the viewers head rather than having to undertake a lengthy adjustment procedure. Once the interpupillary distance between the optical devices is set and the stem 24 and mounting 25 adjusted to correctly position the optical devices on the viewer it is essential that the optical devices are adjusted to ensure that the optical axes of each optical device converge at a central point which is at the working distance of the apparatus. This working distance will generally be within arms length of the viewer and below the normal level of sight of the viewer. Once the actual alignment is correctly set the optical devices are locked into position on frame 12 by the locking screw 14 on collar 13. To ensure that sufficient light is provided at the working distance the frame is provided with a lamp assembly 30. The lamp assembly is mounted on the frame between the optical devices and is co-planar (in a longitudinal plane) with the optical devices. The location of the lamp assembly 30 on the frame midway between the optical devices provides what is termed in the art true co-axial illumination. In other words the light beam and the vision of the user are co-focused and over the area of vision this is termed co-axial illumination. This is very important in intraocular surgery as it produces the red reflex which enables the surgeon to view things which are transparent when performing delicate eye operations. Another way of describing the term co-axial illumination is that the light beam and the point where the user's vision is focused are always co-incident so that when the user changes the field of vision the light beam covers the new object. In the general sense the light beam is co¬ axial with the converging field of vision. The lamp assembly 30, shown in Figure 4 is mounted on frame. 12 and comprises a lamp 31 fitted into a brass socket 32 which is mounted on the wall of the lamp assembly. The lamp 31 projects light through a bicylindrical lens 33 which is spaced from a condensing lens 34 by spacers 35, 36 to produce a gradually- diverging light beam out of the end 40 of the light assembly. The lamp is powered by a twelve volt local power source (not shown) which is connected to the socket by leads 37. The local power source is preferably a battery power pack which is carried by the viewer. The lamp assembly is connected to the frame 12 by an aluminum member 38 which also acts as a shield to the viewer from the heat generated by the lamp. To further insulate the viewer from the heat generated, cork compound heat shield 39 is also provided. As would be appreciated by those skilled in the art the apparatus in accordance with the invention enables a surgeon, jeweller or the like artisan to observe or operate at a level below his/her normal line of sight while maintaining his/her head in an upright position and also allows the viewer to change the field of view by moving the position of his/her head. The invention therefore provides an improved apparatus which overcomes the deficiencies of the prior art.

Claims: CLA1MS: 1. Optical loupes comprising a pair of optical devices (2) mounted on a fram for attachment on the head of a user whereby each optical device is in proximity t a respective eye of the user, characterised in that, each said optical device has a ocular (3), and an objective (4) which defines a field of view, said ocular an objective each has an optical axis (4, 42), the optical axis (42) through the objectiv intersects with the optical axis (4) through the ocular in each case, and light transfe means (23) is located between said ocular and objective for redirecting light from the objective to the ocular whereby an object which appears in the field of view o the objective is capable of being viewed through the ocular. 2. Optical loupes as defined in claim 1 , characterised in that, the optical axis of the ocular and objective intersect at an angle in the range 120° - 150°. 3. Optical loupes as defined in claim 2, characterised in that, the optical axes of the respective objectives converge at an object being viewed. 4. Optical loupes as defined in claim 3, characterised in that, a light source (30) is provided on said frame between said optical devices, said light source providing a gradually diverging light beam directed to illuminate said object being viewed in a manner which gives the effect of true co-axial illumination. 5. Optical loupes as defined in claim 4, characterised in that, said light beam and said optical axes of the respective objectives are co-focused at said object. 6. Optical loupes as defined in claim 5, characterised in that, said frame has respective side arms (24) and a nose support whereby said loupes are worn similar to a pair of spectacles with each ocular proximal a respective eye of the user. 7. Optical loupes as defined in claim 6, characterised in that, said light transfer means is a Schmidt prism. 8. Optical loupes as defined in claim 7, characterised in that, the optical axes of the ocular and objective intersect at an angle of about 135°. 9. Optical loupes as defined in claim 8, characterised in that, each said optical device is mounted on said frame for limited lateral adjustment whereby the interpupillary distance may be adjusted, said optical devices being lockable in position on said frame by respective locking screws (14). 10. Optical loupes as defined in claim 9, characterised in that, each said ocular contains a pair of ocular lenses (6, 7) and a field lens (8) and each said objective contains a pair of objective lenses (18, 19) located at a distal end of the objective.

Inventors: CROCK GERARD WILLIAM, PERICIC LJUBOMIR, TAYLOR HUGH RINGLAND, CROCK, GERARD, WILLIAM, PERICIC, LJUBOMIR, TAYLOR, HUGH, RINGLAND
Applicants: UNIV MELBOURNE, THE UNIVERSITY OF MELBOURNE
Application year: 1992
Main classification: G02B23
IPC codes: G02B23, G02B25