Improved Optical Instrument for Observing Objects not Directly Visible.
Year: 1892

page_text: Date of Application, 10th Aug., 1892-Accepted, 24th Sept.. 1892
COMPLETE SPECIFICATION.
Improved Optical Instrument for Observing Objects not Directly
Visible.
I, JOSEF LIVTSCHAк, of Wilua in the Empire of Russia, Engineer 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 :-
My invention relates to an optical instrument by the aid of which it is possible
to see objects placed within the field of view of the observer, but hidden by some
intervening person or thing. My invention consists of a rod with which are
combined two plane mirrors, one of which is placed in such a position as to receive
the luminous rays proceeding from the object to be observed, and to transmit them
to the other mirror, which is placed close to the eye of the spectator.
On account
of its particular function, I have called the new instrument diascope.
My invention will be more readily understood by reference to the accompanying
drawings, in which :-
Fig. 1 is a rear elevation of my improved optical instrument.
Fig. 2 is a side elevation of the upper part of the same.
Fig. 3 a cross-sectional plan of the same.
Fig. 4 a sectional clevation of the lower part of the same.
Fig. 5 is a side elevation of a modification.
Figs. 6 & 7 are a side elevation and a rear elevation respectively of another
modification.
Similar letters refer to similar parts throughout the several views.
Referring to Figs. 1 to 4, a is the handle by means of which the instrument is
held, said handle being made of one piece with the vertical rod b, or at least rigidly
connected to the same. The handle a is provided with a hole c, serving as a sight
for the observer. At the same height as the said sight, I place the lower plane
mirror d which is arranged to form with the handle a fixed angle of 45° or there-
about. On the rod 61 fit a sliding sleeve e provided with a longitudinal slot f; a
screw g, screwed into the rod b, serves for locking the sleeve e in relation to the
same. At the upper end of the sleeve e, I secure the frame h holding the upper
plane mirror d'; this is accomplished by the following means: The frame his
provided with two shoulders fitting into notches at the top of the sleeve e (see
Fig. 2), and the lower part of said frame, which is enclosed within sleeve e, is
provided with a cross-pin 2, the length of which is identical with the inner
diameter of sleeve e. The upper mirror dis parallel to the lower mirror d.
The employment of the instrument will be obvious. When holding the instrument
by the handle a and looking through the sight c, the observer will see in the lower
mirror d the objects reflected from the upper mirror d¹. Now, as the planes of the
mirrors are parallel to one another, the rays of light incident upon the upper mirror d¹
will be parallel to those reflected from the lower mirror d, that is to say, the
objects will be seen almost as if observed by direct vision. The instrument will be
especially convenient for use in theatres, where parts of the stage are frequently
hidden from the spectator by persons sitting or standing in front of him. In this
case the spectator provided with my improved instrument will raise the upper
mirror d till the concealed object is visible, and will then be able to follow the
whole performance. It will be obvious that the upper mirror d¹ may be easily
taken off, thus facilitating the package of the instrument.
The modification illustrated by Fig. 5 is intended especially for the use of near-
sighted persons. This form of my improved instrument is distinguished from that
described above merely by the addition, opposite the sight c, of a small Galilean

page_text: telescope, as shown at i. The size of the lower mirror d has been somewhat
increased, and the sight arranged to receive the object-glass of the telescope.
r
In Figs. 6 & 7 I have shown a very simple instrument embodying my invention,
which merely consists of a walking-stick, two metal-frames holding plane mirrors,
and suitable means, for instance india-rubber rings, for securing the frames on the
walking-stick. k is the walking-stick, are the frames holding the mirrors d
and d, said frames being constituted by pieces of sheet-metal a portion of which,
1, is bent to a cylindrical shape so as to encircle the walking-stick, the other
portion, l, to which the mirror is attached, being plane and inclined to the walking-
stick at an angle of about 45°. By means of rubber-rings m the frames Ilmay
be secured on the walking-stick at any point. It will be noticed that the mirrors
are located laterally of the walking-stick k, thus a special sight in the latter is not
necessary. The employment of this form of my improved instrument is of course
the same as before described.
'
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
:-
1. An optical instrument constituted by the combination of a rod with two plane
mirrors located thereon so that their distance from each other is adjustable, said
mirrors being parallel to one another, and their reflecting surfaces facing each other,
for the purpose set forth.
2. An optical instrument constituted by the combination, with the handle a,
having sight c, and rod b secured thereto, of the sliding sleeve e, the lower mirror d,
the detachable frame, the upper mirror d', and means for securing sleeve e in
relation to rod b, substantially as and for the purpose described.
3. In an optical instrument of the kind described: The addition of a Galilean
telescope i opposite the sight c, substantially as shown and described with reference
to Fig. 5 in the accompanying drawings.
4. In an optical instrument of the kind described: The combination, with the
walking-stick k, of the frames 1, the mirrors d d', and the rubber rings m, all
constructed substantially as described.
Dated this 10th day of August 1892.
JOSEF LIVTSCHAK,
By Geo. H. Rayner,
37, Chancery Lane, London, W.C., Agent for the Applicant.