US2512153A - Split-field dual-power telescope - Google Patents

Description

L. G. HENYEY ETAL SPLIT-FIELD DUAL-POWER TELESCOPE Filed May 25, 1947 W W a en 1 mwz mm M T E Q MW. a

Jane 20, 1950 Patented June 20 1950 STATES PATENT OFF ICE SPLIT- FIELD DUAL-POWER TELESCOPE- I-iouis GM Henyey' and Jesse L. Greenstein, Williams Bay, Wis.,. assignorsetovthe United, States of America as represented-by theSecretary of War Application-May23, 1947, Serial No. 749,970

4 Claims. (CI. 8832) v This inyentionyrelates to a, splitefleld, dualpower telescopewhich, while,..oi general utility, iaparticularly useiul in. combat tanks and other armored vehicles. is well, known, the. vision from the interior of a tank is extremely limited because .onthenecessity for. protectionto the operatingrpersonneln This =condi tion.oi limited vision israggravatcdyby the restrictedspace within the tank:turret... v In.the;case; oi carrying relativel-yrlarge O8.lib16!g;uIlS, :the, gunner. vhas numerouaduties tdpertorminiadditiontothose customanilyaperformed..bymthe, gunner oi an emplaced gun;-t Eor; example, -thegunner-must ordinaai1y-seleet-a.i'-targe judge {the .ran r, tr t theirgnndqader as t type, oflammunition, watch theetarget movement tocorrectrfon lead and ma: nipulatetheccntrols allundenthestressoibattle I andintaerampedpositionwithin;thevehicle.

1 Underithe foregoing conditionsit is-a greataid to rthe g unner.tozhaveeavailable two. closely adj aent.images creche?and;the?same field of: view, andfat different magnifications.-- The, field of. view oi-zlowen magnifioation yin-covering. a larger area;

enables inspection overr'anrelativelywide area and telescope embodying: the" invention; the tube,

mounting; andzjotherewell-known details being omitted forrsimplicity'iof:illustrationand description u a Figure 2 isra viewishowingfthevmanner' otprodueingvthe upper eccentric. collective lens,

figurefi is'a views shew-ingthemannenofproducingthelmivm? eccentric collective-lens; and

T Figure yisva typiealrview of anzenemy tanlt at 2 two different magnifications, as it appears in the fielder the telescope. I

The lower objective is a telephoto lens of. 10.6" focallength consisting of a pair of doublets I, 2

i and 3, 4. The collective 5 is a semi-circular eccentric=lens cut as shown at Figure 3,;Ircm a large ordinary circular. lens and having its flat edge in the horizontal plane through the central axis of the instrument.

The upper objective is an inverted telephoto lens of 3.l8"focal length, consisting ofthe doublets l5, l6 and H, L These particular objectives are required to make it unnecessary for the objective of longer focus to project an excessive distance in front of the other. The eccentric collective i9 is cut from an ordinary lens, as shown in Figure 2. To prevent light from one objective from passing to the wrong collective and producing false images; the two objectives are separated within their common tube, by a thin metal vane 20. This appears asa diametralline 29', Figure 4. In the absence of specially-cut collectives 5 and. IS, the entrance pupi-lswould be imaged at different points behind the eyepiece and both would be displaced off'the main optical axis 2|. By the use of the collectives, cut as shown at Figures 23 and- 3 to have a prismatic action, the entrance pupils arefocussed to produce a single round Ramsden disk behind the eyepiece. In the model shown, the optical axes of the objectives are displaced\0.55" above and below axis 2|, respectively. Lenses 5 and I9 may be molded in plastic and cut from an ordinary lens 246 in diameter by a straight chordalcut ofiset 0.55" from their center, and: a semi-circular cut centered on the midpoint of the chord.

The second collective lens 6. is a single element extending over both objectives. This lens may have a flat rear face and is designed to be free of significant aberrations. The'rear vertex. of lensfi lies in the same transversesplane as the front of lens 6. Theirontfacesof lenses 5and it are coplanar and, since these two are of differentthickness, as shown in the accompanying table, the plane of the vertexof [9 lies" .014" forwardly. ofthe plane of the vertex oflens 6;- By thisarrangement', the two reticles maybe boresightedwith respect to each other at'the factory and. one boresighting in the field properly adjusts both... Reticles of any suitable type and of desired form; may be provided, as by etching, upon the fiatfaces ofv these lenses.

The 'erector consists of the two doublets I, 8 and 9; HL Of conventional 'form, designed to be free r-significant; aberrations. A diaphragm 22; of

Thus, at a single round exit pupil the observer it sees two images of a target as shown at Figure 4. 3

In the lower half of the eyepiece he is able to obtain a view over a relatively wide field. In the model selected for illustration, the field of view of the wide angle side, with a 1.5:: magnification,

is 40 wide and'20 high. In the upper half, a

magnification of 5X is provided with a field 12 wide and 6 high. -No change of eyepiece, or motion of the observers head is required to shift from one magnification to the other; and no light is lost by splitting the entrance rays into two parts. In short, the invention is the equivalent of two telescopes with the added advantage of elimination of motion of the observers head. The definition of the image is of high quality over both fields.

The following table gives the actual values used in the model illustrated, the lens number corresponding in each instance with the numbers used upon Figure 1.

[All dimensions in inches] Separation Lens Radii tum cases a s s W s NNNNFi-i-EN esssssseseeec 9999????". momcweurm u sO tOOwWNO c0000 We'have thus provided a telescope that is relatively simple and inexpensive to produce in quantities. At the same time the instrument is compact and can be built to withstand the shocks, jars, and rough handling incident to service in the field.

In order fully to comply with the requirements of the patent statutes, we have disclosed a specific form of the invention. However it will be obvious to those skilled in the art that different absolute and relative magnifications may be employed and that the fields of view may be varied as to absolute and relative areas. Furthermore, substitutions of equivalents and changes in the relations of the parts will occur'to those skilled in the art after a study of the present disclosure. For example, the: two areas of different magnifications may be separated in a horizontal direction or in any other direction relative to the horizontal or the vertical, merely by arranging the conventional range reticles on the fiat surfaces of elements 5 and [9, so that they will he Vertical 4 I and horizontal when the telescope is in the desired position of rotation about its optical axis. In the absence of such reticles, of course, or where their use is not required, the desired position of rotation may be obtained simply by mounting the telescope in its support for rotation about its optical axis. Also, the line of separation between the two fields may be displaced from the diametral position to give any .10..

desired ratio between the areas of the two apparent fields. For these reasons, the disclosure should be taken in an illustrative rather than a limiting sense; and it is our desire to reserve all .suchchanges as fall within the scope of the subjoined claims.

In the claims, the term "eccentricity as re- 'ferred to eccentric-collective lenses 5 and I 9,

means the distance between the optical axis of the spherical lens from which the eccentric lens was out, and the geometrical center of the eccentric lens. Thus, in the model shown, lenses 5 and I9 have an eccentricity of 0.55".

.Ha'vingthus fully disclosed our invention, what we claim and desire to secure by Letters Patent 1s:

1. In a split-field dual-power telescope having a central optical axis, a first objective comprising a first telephoto lens in normal position and having its principal axis offset a predetermined. distance from and parallel with, said central axis, a second objective comprising a second telephoto lens in inverted position and of lesser focal length than said first lens, said second lens having its principal axis offset by said predetermined distance from said central axis, said two principal axes forming diametrically opposite elements of a cylinder having its axis on said central optical axis, a first semi-circular eccentric collector lens optically centered on the principal axis of said first objective, a second semi-circular eccentric collector lens optically centered on the principal axis of said second objective, said collector lenses having an eccentricity equal to the radius of said cylinder and having their 'diametral edges contiguous and their forward faces coplanar, a third collector lens adjacent and extending over both said first and second collector lenses, erector lens means and an eyepiece both having their principal ax es coincident with said central optical axis, said collector lenses bringing to a common focus the entrance pupils of discrete difierently magnified images of a common field of view projected by said objectives and centered on said central optical axis, and an opaque vane in said telescope on said central axis and extending between said objectives and first'and second collector lenses.

2. In a split-field, dual-power telescope having a principal optical axis, first and second objectives of different focal lengths having their central axes parallel with and offset on respective diametrically opposite sides of said principal optical axis, said first and second objectives being separate telephoto lenses in-side-by-side parallel relation, one said telephoto lens being inverted with respectto the other to project at different magnifications, discrete images of the same remote field of view, a single eyepiece centered on said principal axis rearwardly of said objectives. and optical means comprising first and second prismatic collective lenses lying in a common lane across said principal axis between said objectives and eyepiece,each said collective lenses being constructed and arranged to direct the entrance pupil of'a respective objective into said eyepiece to form a single exit pupil rearwardly thereof.

3. In a dual-power, split-field telescope having a central longitudinal axis, a first objective having its principal axis parallel with said central axis and offset therefrom a predetermined distance, a second objective having its principal axis parallel with said central axis and offset therefrom on the side opposite the principal axis of said first objective,all said axes lying in a common plane, said objectives being separate telephoto lenses lying in side-by-side relation, one said telephoto lens being inverted with respect to the other, a common erector lens and an eyepiece for both said objectives, and centered on said central axis, first and second coplanar semicircular prismatic collector lenses mounted with their diameters in contact between said objectives and said eyepiece, each said collector lens having an eccentricity equal to said predetermined distance and constructed and arranged in conjunction with said erector lens and eyepiece, to focus the entrance pupil of its objective to a single exit pupil rearwardly of said eyepiece.

4. In a dual-power, split-field telescope having a central longitudinal axis, first and second objectives of difierent focal lengths in fixed adjacent side-by-side relation with their respective optical axes parallel to and equally spaced on opposite sides of said central axis, said objectives comprising separate telephoto lenses one of which is inverted with respect to the other, an eyepiece having its principal axi coincident with said central axis, and a collective lens comprising first and second semi-circular eccentric lenses in a common plane between said objectives and eyepiece, said collective lenses each having an eccentricity equal to the spacing of each said optical axis from said central axis and having their diametral edges contiguous, said collective lenses focusing together in a common plane through the focal point of said eyepiece, the entrance pupils of said objectives, whereby an observer at said eyepiece may see in the exit pupil, discrete images of a common field of view at different magnifications.

LOUIS G. I-IENYEY.

JESSE L. GREENSTEIN'.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 578,459 Leuner Mar. 9, 1897 841,262 Martin Jan. 15, 1907 1,094,724 Konig Apr. 28, 1914 1,290,777 OBrien Jan. 7, 1919 1,840,931 Bjorn Jan. 12, 1932 1,986,731 Kollmorgen Jan. 1, 1935 2,388,673 Brown Nov. 13, 1945 2,409,186 Bouwers Oct. 15, 1946 FOREIGN PATENTS Number Country Date 15,123 Great Britain of 1911 1,727 Great Britain Nov. 18, 1915 312,317 Germany Oct. 18, 1921

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