Improvements in and relating to Achromatic Refracting Lenses and Method for Manufacturing the same.
Year: 1899

page_text: Date of Application, 4th Sept., 1899
Complete Specification Left, 2nd June, 1900-Accepted, 18th Aug., 1900
PROVISIONAL SPECIFICATION.
Improvements in and relating to Achromatic Refracting Lenses and
Method for Manufacturing the same.
I, ADRIEN BESANÇON, of 75, Rue du Doubs, Chaux-de-Fonds, in the Republic
of Switzerland, Manufacturer, do hereby declare the nature of this invention
to be as follows:-
It is a well known fact that, in combining two lenses of different dispersive
powers and which are suitably curved the white light may be refracted without
being decomposed. Such combination of lenses are called achromatic.
Now it is also well-known that such achromatism is not very easily realised in
practice and the said achromatic lens-systems or combinations are of relatively
high prices because of the accurate manner in which they must be manufactured if
they are to give satisfactory results.
The present invention is intended to produce by means of a very simple and
cheap method or proceeding a new combination replacing any desired achromatic
lens-combination and working more perfectly than the same.
My invention consists in the combination of one or more lenses of crown-glass
of any desired curve or curves whatever, with a transparent material having a
lower index of refraction than flint-glass and adapted to be applied to the said
lense or between the said lenses of crown-glass in a liquid or semi-liquid state,
the said material being either a permanent liquid or à molten material which
becomes hard again after it has been applied to a horizontal lens or between
two lenses as aforesaid.
The application of such material to the lens or lenses may be made in any suit-
able manner whatever.
If only one lens is to be combined with the said liquid or semi-liquid material
then the said lens may be surrounded by a suitable circle_forming with the said
lens a kind of cup into which the said liquid or semi-liquid material may be
placed.
Or if two or more lenses of crown-glass are to be combined with the said liquid
or semi-liquid material, the same may be surrounded by a circle enclosing the
space left between the two or more lenses, and the said space is then filled up with
the said liquid or semi-liquid material, which may be introduced into the same
through a suitable opening.
In one form, the device consists of a lens of crown-glass having equi-convex
curves. In front of one of its faces there is placed a glass (which may be con-
sidered as a lens of infinite focus) connected to the said lens by means of a ring,
suitably secured to both of them, and the space thus formed between the lens of
the glass is filled up with a transparent material, for example, ioduret of methyl
the dispersive power of which is suitable for this combination.
The index of refraction of this material is 1,52 that is to say equal to that of
crown glass of medium density and lower than that of flint glass which is 1,60
to 1,65.
This combination may be practically mounted by being suitably inserted
between two rings or circles.

page_text: Another combination may consist of two biconvex lenses with a ring and with
a liquid or semi-liquid material arranged between them which material may be
the same as that above referred to.
A further combination may consist of a biconvex lens placed in front of a
plano-convex lens and connected to the same by means of a ring of any suitable
rigid material, the interposing material being lodged in the space between the two
lenses. In this case the liquid or semi-liquid material should have a lower power
of dispersion than in the above described cases.
A still further combination consists of two plano-convex lenses connected with
one another by means of a ring and a liquid or semi-liquid material the dispersive
power of which may in this case be the same as that of crown-glass, is inserted
between the said lenses and the ring.
Dated this 4th day of September 1899
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
Improvements in and relating to Achromatic Refracting Lenses and
Method for Manufacturing the same.
I, ADRIEN BESANÇON, of 75, Rue du Doubs, Chaux-de-Fonds, in the Republic
of Switzerland, Manufacturer, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:--
The present invention has for its object to provide, by means of a very simple
and cheap method, a new combination replacing any desired achromatic lens-
combination and working more perfectly than the latter.
My invention consists in the combination of one or more lenses of crown-glass
of any desired curve or curves, with a transparent material and adapted to be
applied to the said lens or between the said lenses of crown-glass in a liquid or
semi-liquid state, the said material being either a permanent liquid or a molten
material which becomes hard again after it has been applied to a horizontal lens
or between two lenses as aforesaid.
The application of such material to the lens or lenses may be made in any suit-
able manner.
If only one lens is to be combined with the said liquid or semi-liquid material
then the said lens may be surrounded by a suitable circle forming with the said
lens a kind of cup into which the said liquid or semi-liquid material may be
placed.
If two or more lenses of crown-glass are to be combined with the said liquid
or semi-liquid material, the same may be surrounded by a circle enclosing the
space left between the two or more lenses, the said space being then filled up with
the said liquid or semi-liquid material, which may be introduced through a suit-
able opening.
The accompanying drawings show by way of example various forms of carrying
my invention into practice but I do not limit myself to those combinations as
represented therein."
Figure 1 shows a lens a having equi-convex curves. In front of one of its
faces there is placed a glass c (which may be considered as a lens of infinite
focus) connected to the said lens a by means of a ring b suitably secured to
both of them, and the space thus formed between a, b and c is filled up with a
transparent material, such as for example iodide of methyl.

page_text: Figure 2 shows the manner in which this combination may be practically
mounted by means of rings or circles cf.
Figure 3 shows a combination of two biconvex lenses g and h with a ring b
and with a liquid or semi-liquid material d arranged between them which mate-
rial may be the same than as that above referred to.
Figure 4 shows a bi-convex lens placed in front of a plano-
convex lensk and connected to the same by means of a ring b
of any suitable rigid material, the interposing material d being lodged in
the space between the two lenses. In this case the liquid or semi-liquid material d
shown has a lower power of dispersion than in the above described cases.
Figure 5 shows a still further combination of two plano-convex lenses and m
connected with one another by means of a ring band a liquid or semi-liquid
material d is inserted between the said lenses and m and the ring b.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. An achromatic lens-system formed of the combination of one or more suit-
able curved lenses of crown glass with a lens of liquid or semi-liquid, substance
such as iodide of methyl, substantially as described and for the purpose specified.
2. An achromatic lens-system formed of the combination of two lenses of any
suitable curve whatever, or of one such lens and of a flat glass-disc, with a
circle of rigid material holding the said lenses or the said lens and the said disc,
at suitable distance apart and with a transparent lens of liquid or semi-liquid
substance such as iodide of methyl substantially as and for the purpose specified.
3. The method of manufacturing achromatic lens-systems of any kind, by
Leans of combining one or more lenses of crown glass with a liquid or semi-
liquid lens of iodide of methyl, substantially as described and illustrated in the
accompanying drawings.
Dated this 2nd do. of T
1000
HASELTINE, LAKE & Co..
45, Southampton Buildings, London, W.C., Agents for the Applicant.