Portable Monocular With High Magnification

1. Field Of The Invention.

The present invention relates to a portable monocular device which, by providing high magnification, is designed for close-up observation.

2. Summary Of The Invention

The portable monocular device of the invention which forms a light and readily transportable optical instrument, is endowed with high magnification (of the order of 18) and makes it possible, better than a strong magnifying glass or a jeweller's eyepiece (instruments which are too short and difficult to fit in the eye) and without having recourse to a binocular device, to observe objects which are substantially invisible to the naked eye and to fix a precise point to be observed (e.g. an insect larvae in agriculture, for identifying it, studying its stage of development, ect. . . . and determining the best treatment times).

According to the invention, the device comprises an elongate housing, open at its ends, on one end of which is fixed an eyepiece and comprising, inside its other end, two biconvex lenses which are of the same power and which are disposed in parallel grooves formed inside the support.

In a particular arrangement, the distance A between the two biconvex lenses is defined by the equality A=(f1)/2 (f1 representing the focal distance of the first lens), this distance A being less than or equal to the diameter of said first lens. The relation between the distance A and the distance B separating the second lens and the eyepiece will then be such that

The monocular device may be formed (except for the optical parts) from a plastic material or a light material, and may have a cylindrical shape or any other suitable shape.

To facilitate cleaning, the eyepiece of the monocular device may advantageously be provided with a plain glass.

The presente invention will be better understood from the following description of a preferred embodiment, with reference to the accompanying schematic drawings in which:

FIG. 1 is an exploded view of the main component elements of a portable monocular device in accordance with the invention;

FIG. 2 is a longitudinal section of the assembled device through line II--II of FIG. 3; and

FIG. 3 is a cross sectional view of the device.

The monocular device shown comprises a cylindrical shaped body made from a plastic material and formed of two parts 2,3 with spherical grooves 5,5' disposed, at one end, on its internal face. In a typical example, the cylindrical body has a length of 75 mm, an inner diameter of 17 mm and an outer diameter of 22 mm. The first groove 5 is situated at 2 mm from the aperture of the cylindrical body and the second groove 5' is at a distance A=15 mm from the first groove. Two biconvex lenses 4, 4', each of a power of 33 diopters; with a magnification of 9 and a diameter of 18 mm, are inserted respectively in grooves 5,5'. Opposite the lenses 4,4' an eyepiece 1, provided with a plain glass, is fitted on the cylindrical body so that a distance B=45 mm separates the plain glass of the eyepiece 1 from lens 4'. The distance A=15 mm has been chosen to be half the focal distance f of lens 4 and so as not to be greater than the diameter of this lens.

The monocular device has the feature of being very readily dismantled. For this it is sufficient to remove the eyepiece 1 from the cylindrical body formed of elements 2,3. These two elements are fixed together by a male-female closure system 6,7 (any other appropriate system of the same kind could be used).

In order to be able to grip it better, the body of the monocular device may be provided with grooves on its external surface.

It will be understood that the above description has been given by way of example, without any limitative character, and constructional additions or modifications could be made without departing from the scope of the present invention.