US1095932A - Prism. - Google Patents

Description

any MAOfiL-JL PRISM.

APPLICATION FILED DEO.1, 1913.

Patented May 5, 1914.

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CARL SCH'UTZ, OF CASSEL, GERMANY.

PRISM.

Specification of Letters Patent.

Application filed December 1, 1913.

Patented May 5, 1914. Serial No. 804,033.

To (/71 zr/mm it may concern:

Be it known that I, CARL Scnii'rz, a subject of the German Emperor, and resident of tassel. in the (lei-man Empire, have invented an Improved and Novel Prism, of which the following is a specification.

Regarding the construction of prisms, which are employed in telescopes and other optical instruments and which have totally refracting surfaces as active surfaces, there has always existed the tendency to diminish the number of the changes of media, and it is in pursuance of this tendency that two coacting prisms have been united by putty with each other. This layer of putty has. however, a lightwcakening ell'ect, even if the best material is employed, and if. moreover, also a diaphragm becomes necessary, the superposed surfaces form the source for a variety of objectionable features. First, if no putty has been employed, the respective surfaces become dull after some time of use; second, if putty has been employed, the thus effected connection is not durable, especially with regard to instruments connected to firearms. so that the prisms become displaced with regard to each other after some time; finally the mounting of such prisms with regard to each other is very difiicult. All these drawbacks are entirely overcome by my present. invention, the gist of which resides in making the two prisms integral. Manufacturing such prism body is, however, particularly difficult if of two surfaces which join under an angle of less than 180 one or the other is to be ground and polished. Now, according to the. present invention, such a surface is elongated beyond the line of intersection of the two surfaces into the other surface by means of incisions of such a kind that the first mentioned surface may be ground and polished throughout its whole extent. After this, the incisions are, or may be, filled up.

with a non-transparent material and transformed into a diaphragm.

In order to make my invention more clear, I refer to the accompanying drawing, in which similar letters denote similar parts throughout the several views, and in which:

Figures 1 and 3 are diagrammatical representations of two different forms of construction of my improved prism; Fig. 2 shows two coacting porro-prisms.

Referring first to Fig. 2, the ray of light, after having passed through the objective,

strikes the surface 1 in the point 2 at a right angle to this surface; itthen passes to the point 25 of the surface at, is totally reflected at and from this point to the point 5 of the surface (3, is again totally reflected, and leaves the prism at and through the point 7 of the surface 1 The ray now passes through the air to the other prism making thcn exactly the same way through this second prism as has just been described with respect to the first of the two prisms. It leaves the second prism at the surface S, passing then into the ocular.

The prism system just mentioned can but diflicultly be mounted because the fastening must be etfcctcd at the broken edges 9-10 and 11-12. To obviate the passage of the ray of light through the air, it would be necessary to connect the prisms by putty, and by displacing the same in regard to each other in the direction of the ray of light, passing from one prism into the other, their relative position being then that represented in Fig. 3, but the invention provides a union not by putty or the like but by the material of the prisms themselves, 11. e. by making the two prisms integral, or in one respectively. The favorable effect so obtained may be still considerably increased by giving the prism body the shape shown in Fig. 1. The ray enters the prism body at right angles to the surface 13, and after having been totally reflected four times within the prism body it leaves the latter through the surface 1% atright angles to the same. The two prisms forming the prism body are coherently united with each other at the quadrangle 15, 16, 17, 18, there being thus no superposed refracting surfaces or putty surfaces, which always cause a loss of light. Moreover, the working up of two surfaces is saved, which, is also worth to be mentioned. Supposed, a diaphragm be required at the place in question, it is only necessary to make an incision at the shaded portion 01 the prism body by means of a saw and to fill up this incision afterward with black varnish or lacquer, black paper or the like. The whole prism body resembles now a simple lens in so far as only one point of entrance and only one point of exit exists, and there is, moreover, the further advantage that the large surface 15, 19, 20, 21, 17, 22 may be utilized for mounting the prism body, which,

besides, is true also of the similarly shapedand situated surface of the lower side of the prism body. Furthermore the location of that surface is suclr that the prism body when mounted in operative position retains its stable equilibrium. Finally, also the advantage that all surfaces are accessible for cleaning is worth to be mentioned.

The form of construction represented in Fig. 1 allows also of a certain saving in material because pieces may be cut off parallel to the surfaces 19, 15, 16, 23 and 15, 22, 24, 16, the thickness of said pieces being such that the section lines are tangents to circles inscribed into the squares 19, 20, 21, 17 and 18, 25, 26, 24.

Having now described my invention, what I desire to secure by Letters Patent of the United States is:

1. A prism body composed of two prisms adapted to co-act and being integral one with the other, and an incision 0r incisions situated at and between two prism surfaces joining under an angle of less than 180, substantially as described.

2. A prism body composed of two prisms adapted to co-act and being integral one with the other, and an incision or incisions situated at and between two prism surfaces joining under an angle of less than 180, the position of said incision or incisions being such as to elongate, of the two surfaces, that to be ground and polished into the other one beyond the section line of them, substantially as described and for the purpose as set forth.

A prism body composed of two prisms adapted to eo-act andheing integral one with the other, and an incision orincisionssituated at and between two prism surfaces joining under an angle of less than 180, and a nontransparent filling-out material located Within said incision or incisions, substantially as described and for the purposes as set forth.

In testimony whereof I affix my signature in presence of two witnesses.

CARL soHUTz.

\Vitnesses FERDINAND Pii'rz, ERNST Bonn-En.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C."

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