Optical instruments

Details Optical instruments Optical instruments

1998-03-05

2002-05-28

Mack, Ricky (Department: 2873)

Optical: systems and elements

Lens

With support

C359S819000

Reexamination Certificate

active

06396649

ABSTRACT:

The invention relates to optical instruments and in particular housings for optical instruments; and optical components adapted to be accommodated by said housings.
Light, isotropic or otherwise, refracted by lenses and/or reflected by mirrors is used in any number of optical devices. The conventional selection and arrangement of lenses and mirrors can be used to advantage to make, amongst other things, optical instruments that magnify images. Examples of such optical instruments include microscopes and telescopes. Both of the aforementioned instruments magnify images, but the latter is specifically adapted to view distant objects. The way light is manipulated in any number of optical instruments will not be considered herein in great detail, suffice to say that it is well known to those skilled in the art that a selected combination of lenses and mirrors can be used to advantage to alter the path of light for any selected purpose, including, but not limited to, the ones aforedescribed.
Common to all optical instruments is the need to provide at least one optical path, that is to say optical components must be precisely positioned with respect to each other in order to ensure that light entering the instrument travels a predefined pathway. Thus, for example, light may be made to focus at a given location before, for example, being made to travel in an alternative direction or even being split to provide for a multiplicity of beams which are similarly made to travel in a predetermined direction, where each resultant beam may be made to travel in a different direction with respect to the other resultant beams.
It will be apparent from the above that the alignment and positioning of optical components in an optical instrument is critical and/or crucial. This can be illustrated having regard to the optical schematic shown in FIG.
1
.
The microscope represented in
FIG. 1
comprises a fibre optic light source 1× which, briefly, emits a beam of light that is focused by refraction, via lens 2× and compensated via a compensating plate 3×. The beam of light is then used to illuminate an object and is reflected from same so as to strike a beamsplitter plate 4× and to be reflected through an angle of 90° and thus made to travel along an axis perpendicular to the optical axis and towards two cameras 5× and 6× (one with a narrow field of view and one with a wide field of view). Although in the microscope illustrated in
FIG. 1
light is directed towards cameras it may be alternatively directed towards an eyepiece. In the arrangement shown, the lenses are selected so as to provide a magnified image of the object to be viewed.
The positioning of each optical component in the aforedescribed optical system is critical if a distortion-free image is to be achieved. For example, if lens
1
and the beamsplitter plate are misaligned then a distorted image will be obtained which will appear ultimately on the camera as an inaccurate representation of the image to be viewed.
Hitherto, the manufacture of optical instruments has involved machining a housing with a plurality of bores, each bore being machined to accommodate selected optical components. It will apparent that as the machining takes place the orientation of the housing will be sequentially changed and that the machining process will take place in intervals. This process of periodic machining, in combination with a change in housing orientation, introduces errors into the alignment of housing bores and thus into the alignment of optical components positioned within the housing. Moreover, the bores are machined so as to frictionally hold each of said components. However, it will be apparent that any machining of this type must involve a certain amount of tolerance if the optical component is in fact to pass through the bore. Thus it is possible for any optical component so positioned to be misaligned by only a small amount but by an amount sufficient to deleteriously affect the image to be achieved.
It follows from the above that the greater the number of optical components to be positioned within a housing then the greater the propensity for error and the more difficult the task. This is especially true for microscopes because they use a combination of lenses in order to provide for enhanced magnification since magnification is determined by the product of the separate magnification of each lens.
In addition to the above, the positioning and alignment of square-shaped components is rendered difficult using a conventional housing because of the differences in geometry.
It therefore follows that hitherto the manufacture of optical instruments has involved a considerable amount of time, skill and labour. Moreover the manufacturing tolerance of such instruments is in the order of tens of microns eg 20-30 microns for the type of microscope illustrated in FIG.
1
.
In addition to the above, and in particular in relation to microscopes, it has always been the case that the turret for accommodating objective lenses has been mounted on the microscope so that its angle from the vertical is offset, for example, by 19°. The offset angle is designed to prevent impact between an objective lens and an object which may result because of the different working lengths of various objective lenses. The mounting of the turret at an angle is a feature that involves a considerable amount of engineering since a part of the instrument to which the turret is to be attached has also to be similarly machined so that it can accommodate a turret mounted at an angle to the vertical. Similarly, other fixtures and fittings are affected by this safety feature and thus represent a manufacturing investment in terms of labour, skill and time.
Given the above information, it is an object of the invention to provide a housing for an optical instrument which enables the assembly of the instrument in an inexpensive and a relatively easy fashion.
It is a further object of the invention to provide a housing that can be machined in a way that involves a relatively small number of machining steps and ideally a single setting for a machining tool.
It is yet a further object of the invention to provide a housing which enables an optical instrument to be assembled with relatively little skill.
It is yet a further object of the invention to provide a housing which facilitates the alignment of optical components to a common optical axis and moreover provides for the reliable and reproducible alignment of said components. It is therefore an object of the invention to provide a housing which facilitates the creation of an optical pathway.
It is another object of the invention to provide a housing which enables the registration of optical components.
It is yet a further object of the invention to provide a housing which minimises aberrations in an optical image and thus provides for a more desirable optical instrument.
It is yet a further object of the invention to provide a housing which reduces the time required for assembly and alignment of the system, which exhibits mechanical and thermal stability, which reduces the hitherto complexity of the optical instrument system and so eases manufacture and reduces the emphasis on manufacturing tolerance and which also provides for simple and easy repair and replacement of any one or more component(s) of the optical system.
It is also a further object of the invention to provide optical components adapted to fit in the housing of the invention so as to be securely and reliably held in place and so as to be easily replaceable especially for repair and maintenance.
STATEMENT OF THE INVENTION
In its broadest aspect, the invention concerns a groove or channel having at least two surfaces positioned perpendicular with respect to each other so as to provide reference surfaces against which a component can be positioned.
According to a first aspect of the invention there is therefore provided a housing for an optical instrument which housing is provided with at least one channel means having, in section, at least two

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