Year: 1897

page_text: I, HENRI LOUIS HUET, of 14, Rue du Temple, Paris, France, Optician, do
hereby declare the nature of this invention, to be as follows:
This invention relates to the optical prism or block forming the subject of a
previous Application for Letters Patent No. 14,102 dated June 9th 1897, for
reversing the image with or without lateral displacement of the optical, axis.
This optical prism or block produced three successive reflections of the light
rays in the same plane for effecting the reversal of the image in one direction
the reversal in two directions perpendicular to each other being obtained by the
substitution for one of the three planes of reflection, of a right-angled dihedron:
It will be easily understood that in general, in order to obtain a reversal in
one direction it is necessary and sufficient that the number of reflections of the
light should be odd, the sum (or the difference) of the angles of reflection being
however a multiple of two right angles in order that the direction of the rays
shall on leaving the prism be parallel to the direction in which they entered.
The present improvements relate to an optical prism more particularly designed
to enable the length of the instrument to be reduced and the use of silvered
surfaces to be dispensed with so as to avoid loss of light.
The improvements consist essentially in so 'forming the optical block or
prism:
(1) That a greater odd number of successive reflections of the light rays
and
consequently a bending back of the axis a large number of times is produced
so as to considerably reduce the length of the instrument in which the prism is
mounted;
(2) In employing exclusively, total reflections so as to avoid the loss of light
incidental to the use of silvered surfaces;
(3) In employing for one of the reflections the entering or exit surfaces.
The invention also relates to the construction of a binocular having the prisni
applied thereto.
Reference is to be had to the accompanying drawings forming part of this
specification which illustrate various forms of prisms having five planes of reflection.
Figures 1, 2, 3, and 4 represent various forms of prism for reversing the image
and also displacing it laterally. Figure 5 shews a prism for reversing the
image without lateral displacement. Figure 6 shews another form of prism for
obtaining a considerable lateral displacement of the image for producing a
highly stereoscopic effect. Figures 7 and 8 shew a face view and plan of a
binocular glass having eye-pieces adjustable for width and prisms giving lateral
displacement of the image. Figure 9 is a cross-section on line 1-2 Figure 8
and Figure 10 a longitudinal section on line 3-4 Figure 8. Figures 11 and 12
shew in horizontal and vertical section the interior of one of the two barrels of the
binocular. Figure 13 shews a binocular provided with the optical blocks of
prisms and adapted for use as a telemeter. Figure 14 shews a binocular having
CD 071

page_text: toothed, pinions 1m each gearing with a rack n on the inner sliding member of
each of the two telescopic slides gh. Within the tube k is fitted to turn freely
another tube (Figure 10) internally threaded to receive a tube q which is
screw-threaded at its lower part and attached to the fixed part of the upper
slide i for effecting the extension of the eye-pieces. The tube o is turned by a
milled head r on said tube.
The binocular which always remains flat may be replaced in its case without
alteration of the adjustment for width of the eye-pieces, the case being large
enough to contain it at its full width. The binocular with adjustment for width
of eye-pieces may also have a rapid drawing out motion while still retaining the
focusing motion.
It may be employed as a stadiometric telemeter by the addition (as shewn in
Figure 13) of a double refraction or duplication prism or prisms s s¹ at an angle
determined according to the base adopted the prism or prisms being placed either
in front or in rear of the objective.. It is to be understood that the optical prism
herein described may be applied to a single barrel.
Hated this 21st day of December 1897.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.
I, HENRI LOUIS HUET, of 14, Rue du Temple, Paris, France, Optician, 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:-
This invention relates to the optical prism or block forming the subject of
previous Letters Patent No. 14,102 dated June 9th 1897 for reversing the image
with or without lateral displacement of the optical axis. The said optical prism
or block produced three successive reflections of the light rays in the same plane for
effecting the reversal of the image in one direction, the reversal in two directions
perpendicular to each other being obtained by the substitution for any one of the
three planes of reflection, of a right-angled dihedron.
It will be easily understood that in general, in order to obtain a reversal in
one direction it is necessary and sufficient that the number of reflections of the
light should be odd, it being necessary however, that the sum (or the difference)
of the angles of reflection should be a multiple of two right angles in order that
the direction of the rays shall on leaving the prism be parallel to the direction in
which they entered.
The present improvements relate to an optical prism more particularly designed
to enable the length of the instrument in which it is employed to be reduced and
the use of silvered surfaces to be dispensed with, so as to avoid loss of light.
The improvements consist essentially in so forming the optical block or
prism:
(1) That a greater odd number of successive reflections of the light rays and
consequently a bending back of the axis a large number of times is produced
so as to considerably reduce the length of the instrument in which the prism is
mounted;
(2) In employing exclusively, total reflections so as to avoid the loss of light
incidental to the use of silvered surfaces;
(3). In employing for one of the reflections, the entering or exit surface.

page_text: The same arrangement may be adopted for a binocular having blocks or prisms
giving no lateral displacement of the image as in Figure 14. This mode of
mounting also permits of a rapid drawing out of the eyepieces to a focus regulated
by the screw adjustment and it is equally adapted for blocks or prisms producing
a considerable lateral displacement of the image.
I have also specified in the said former patent before referred to, that the flat
form of the block or prism possesses the advantage of rendering the instrument
less cumbrous and capable of being carried in the pocket. With this object, the
binocular provided with the block or prism is furnished with an adjustment for width
which is not liable to be disturbed, as well as a focussing motion controlling both
eye-pieces. For the purpose of adjustment for width three transverse slides (see
Figure 8) are used instead of the usual central joint, so as to permit of centreing
the eye-pieces to suit the distance apart of the eyes. These slides ghi are
telescopic, their two members being fixed respectively to the two barrels of the
binocular, the adjustment for centreing being effected by a milled head on the
outer tube of the central pillar, which tube carries toothed pinions Im each
gearing with a rack on the inner sliding member of each of the two telescopic
slides gh. Within the tube is fitted to turn freely another tube o (Figure 10)
internally threaded to receive a rod q which is screw-threaded at its lower part
and attached to the fixed part of the upper slide i for the focussing motion of the
eye-pieces. The tube o is turned by a milled head r on said tube.
The binocular which always remains flat may be replaced in its case without
alteration of the adjustment for width, the case being large enough to contain it
at its full width. The binocular with adjustment for width may also have a rapid
draw out motion of the eyepieces to a focus regulated by the screw adjustment
The binocular provided with the optical prism or block as described may also
be employed as a stadiometric telemeter by the addition in the usual and well
known manner as shewn in Figure 13 of a double refraction or duplication prism
or prisms ss, at an angle determined according to the base adopted, the prism or
prisms being placed either in front or in rear of the objective. It is to be
understood that the optical prism herein described may be applied to a single
barrel, so as to form a simple monocular glass.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
1. The herein described improvements in optical prisms or blocks of the kind
herein before specified which consists:
(a) In producing a greater (uneven) number of successive reflections of the light
rays and so effecting a considerable diminution of the length of the instrument.
(b) In using only total reflections so as to avoid the loss of light incidental to
the employment of silvered surfaces.
(c) In utilizing the entering or exit surface of the optical block or prism as a
reflecting surface.
2. A binocular having the optical blocks or prisms mounted in the barrels thereof
and a focussing motion controlling both eye-pieces in combination with means of
adjustment for width, consisting of telescopic slides operated by rack and pinion
motion, so that the barrels remain in the same plane, and the flat form of the
instrument is preserved, substantially as herein before described and illustrated in
the accompanying drawings.
Toted this 30th day of September 1898.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.