CA1093355A - Binocular telescope with off axis reflectors - Google Patents
Binocular telescope with off axis reflectorsInfo
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- CA1093355A CA1093355A CA290,234A CA290234A CA1093355A CA 1093355 A CA1093355 A CA 1093355A CA 290234 A CA290234 A CA 290234A CA 1093355 A CA1093355 A CA 1093355A
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/02—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices involving prisms or mirrors
- G02B23/06—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices involving prisms or mirrors having a focussing action, e.g. parabolic mirror
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- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Telescopes (AREA)
Abstract
Hale 6 c/w BINOCULAR TELESCOPE WITH OFF AXIS REFLECTORS
ABSTRACT OF THE DISCLOSURE
A binocular telescope having two separate, essentially identical, optical systems. Primary reflector of each system is an off-axis paraboloid, the axis being at an edge of, or clear off the primary reflector. The diagonal plane mirrors or 45° prisms of conventional Newtonian telescopes are eliminated by using modified Porro prisms which produce corresponding images near adjacent inner portions of each optical system. Line joining axes of eye piece is inclined to optical axes for comfortable viewing. The off-axis primary mirrors cause less block-age than prior art Newtonian reflectors and in one exemplification the blockage is eliminated completely.
The optical axes are set to be parallel by a simple collimation procedure. Interocular adjustment is attained by swinging the optical systems relative to each other about a hinge axis which is parallel to optical axes, thus altering axial separation whilst maintaining the optical axes parallel.
ABSTRACT OF THE DISCLOSURE
A binocular telescope having two separate, essentially identical, optical systems. Primary reflector of each system is an off-axis paraboloid, the axis being at an edge of, or clear off the primary reflector. The diagonal plane mirrors or 45° prisms of conventional Newtonian telescopes are eliminated by using modified Porro prisms which produce corresponding images near adjacent inner portions of each optical system. Line joining axes of eye piece is inclined to optical axes for comfortable viewing. The off-axis primary mirrors cause less block-age than prior art Newtonian reflectors and in one exemplification the blockage is eliminated completely.
The optical axes are set to be parallel by a simple collimation procedure. Interocular adjustment is attained by swinging the optical systems relative to each other about a hinge axis which is parallel to optical axes, thus altering axial separation whilst maintaining the optical axes parallel.
Description
~ ~ 3 3 BACKGROUND OF THF. lNVENTION
Field of the invention The inven~ion relates to a binocular telescope having two modiEied Newtonian viewing systems, being adapted materially to reduoe, and in one exempliication to eliminate, light blockage which is characteristic of a Newtonian telescope.
Prior art A common Newtonian telescope has a paraboloid reflector converging a parallel entering pencil to a principal focus which, if uninterrupted, would be on the optical axis. A forty-five degree reflector, which can be a front surface mirror, is placed generally central of the optical axis and spaced inwards from the principal focus towards the reflec~or by a distance in excess o~ half the diameter of the primary so as to intercept the converging reflected rays to form an image clear of the entering pencil.
As is well known, a Newtonian telescope has many advantages, and has a major disadvantage in that the reflecting mirror results in blockage of entering rays.
;~ 25 Canadian Patent 768,402 issued 2~ March 1964 to the present inventer, and equivalent foreign patents and applications, teach a Newtonian conig-uration using a half re1ector of generally semicircular orm. As is later explained in detail, the hal~
reflector has an optical axis su~stantially on a diametric cord forming an edge of the hal reflector.
3 3 ~c~j Th~ls a very ~n~lch smaller re:~lector can be used with consequent materi~l recluction of blockage.
OUTLIN~ OF THE INVEMTION
The present invention provides a Newtonian optical system with an off-axis primary reflector having an optical axis adjacent to an edge, conse-quently light blockage can be materially reduced and, in one exemplif:ication, eliminate~l. ..
A binocular telescope according to the present invention provides a left hand optical system with an off-axis parabolic reflector, and a reflecting means on the optical axis placed inwards from the principal focus towards the primary by a distance such as to intercept the reflected rays so that an image of a distant object is formed clear o the entering rays, viewing optics being provided to observe the image. A right hand optical system similar to the left hand optical system is provided, the two systems being constructed and arranged for binocular observation of the images. Means are provided to effect collimation o the binocular so that the optical axes o each system are parallel, : and means are provided to adjust the interocular distance of viewing optices so as to accommodate individual variation in interpupilliary distance without ~: materially~disturbing the parallism of the optical - axes.
In one exemplification of a binocular ~: telescope according to the present invention the of-: 30 axis primaries have off axis distances equal to or greater than an amount by which the re1ecting means ~ would, otherwise, block rays of the entering pencil, : . - 3 -, 335~
so thlt all of the rays of the pencil enter ancl are re flected by ~he off-axis primary, and are intercepted by ~he reflecting means, wi~hout blockage~
A detailed description following related to drawings gives exempli~ication of the present invention which, ho-~ever, is capable of expression in structure other than that particularly described and illustrated, DESCRIPTION OF THE DRAWINGS
Fig. 1 is an optical diagram o a prior art Newtonian re1ecting telescope, FigJ 2 is an optical,diagram illustrating a principle of the present invention, Fig. 3 is a detail perspective diagram of a known Porro type prism, Fig. 4 is an end elevation of a configuration gene-rally as Fig~ 2 seen from 4-4 of Fig. 2, and having a prism according to Fîg. 3~
Fig. 5 shows a first configuration as Fig. 4 with a second coniguration generally similar to the first configuration, the configurations ; ~orming a Newtonian binocular exemplary o~ the the present invention9 some adjustment para-meters being exaggerated for clarity, Fig. 6 is a light ray diagram of the embodiment of Fig. 5 Figso 1 through 6 are diagrammetrlc~
Fig~ 7 is a top perspective o a Newtonian binocular telescope having an optical diagram as Fig~
~30 6, ;;; - 4 -.
~ ~ 39~5 ~
Fig. 7-A is a fragmented elevation of a mounting assembly partly broken away to show a collimation adjustment means, ; 5 Fig. 8 is a perspective of the telescope of Fig. 7 seeo from 8-8 Fig, 7, Fig. 9 i5 a detail perspective of a Porro prism assembly showing adjusting means, Fig. 10 is an optical diagram illus~rating an alternative embodiment without obstruction ~o an entering pencil, Fig. 11 is an end elevation of the alternative embodiment seen from XI-XI Fig. 10, Figs. 10 and ll are diagrammatic.
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DETAIL DISCLOSURE
Prior Art Prior art is discussed in some detail below, in order to distinguish Canadian patent 768 ,402 aforesaid fr~m the structure of the presen~ invention.
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The Canadian patent is also discu~sed in detail sufficient to show how the present invention distinguishes over~structure accordin~ to the : : ~
patent.
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Prror Art Newto arl, Fl~. 1 Fig. 1 which is prior a-rt, is a diagram o~ a Newtonian reflecting telescope. The telescope 10 has a primary paraboloid re1ector 11, ~f diameter D,having ~n optical axis 12, with a prirlcipal focus F on the optical axis at a dis~ance from the primary reflector equal to its focal length. Ent:ering rays 139 13.1 from a distant object are parallel t:o the axis, striking the primary. The entering rays are reflected as seen at 14~ not interrupted, the reflected rays converge to focus at F. A 45 reflector 15 on the optical axis, spaced a distance A inwards towards the primary, A as seen being ~omewhat greater than D/2, causes the rays to converge at F' forming an inverted image of the distant object, F' being clear of the entering rays. A exceeds D/2 by a clearance ~A, Fig. 1. The image is observed by a suitable objective system, the re~lector 15 is commonly a plane ront surfaced mirror.
Canadian patent 768,402 issued 24 March 1964 to the present inventor, and equivalent foreign patents and applications, ~each a Newtonian configuration using a half reflector of generally semi-circular form. In prior known constructions such as illustrated in Fig. 1, the 45 reflector lS is spa ed inwards in the optical axis a distance in excess of D/2 so that Fl is clear of the entering rays, as explained~ In a con~iguration according~to the patent aforesaid9 the half reflector has an optical axis substantially on a diametric cord orming one edge of the half reflector.
The distance measured along the optical axis from F to the mirror l5 is designated A in Fig. 1, where A is greater than D/2 by the amount ~a. As is well known, blockage and consequently loss of light occur ~ ~ 3 ~ 5 from obstruct:ion causecl by the 45 mirror 15, which obstr~lction increases with increase of diameter of the reflector, focal length remaining constan~. It is clear that, in a construction according to the patent above, since the optical axis of the half reflector lies along an axial edge oE a pencil of parallel entering rays, A can be greatly reduced to AA with consequent reduction in blockage.
Fi~. 2, off axis Newtonian Fig. 2 is a diagram to illustrate a principle of the present invention, being also a Newtonian configuration. In Fig. 2 a telescope configuration, an optical diagram of which is designated generally 20, has an off-axis paraboloid primary reflector 21 having an optical axis 22 and a principal focus F, with the optical axis being at an edge o~ the primary. Entering rays 23, 23.1 of a pencil of rays parallel to the axis are reflected as seen at 24 and 24.1 and would, if uninter-rupted, converge at the principal focus F, the entering ray 23.1 and the reflected ray 24.1 being axial. In Figs. 1 and 2, F' is clear of the entering pencil.
Clearance is exaggerated in Fig. 1 and 2 for clarity.
Consequently with a reflecting means, namely a 45 mirror 259 placed on the optical axis 22 an image is formed at F' as before, but the 45 mirror 25 need only be spaced inwards by the distance ~A, ~A being very m~lch smaller than A Fig. 1. Thus there is minimal light blockage since the mirror 25 can be smaller than the mirror 15 in a ratio ~AjA. In Fig. 2, the entering and reflected axial rays 23.1 and 24.1, and adjacent paraxial rays are, in actuality blocked by the mirror 25, and these rays not reflected as shown. Image formation in Fig. ~ is shown thus conventionally or clarity, and is so shown ~, .
~ 3 3~j~
succeeding figwres. The optical axis is seen to be within the blockage.
Figs. 3 and 4 Fig. 3 is a detail perspective diagram of a Porro type prism 26 of a well Icnown kind, wherein li~ht is totally reflected inside two 45-90 prisms at right angles to each other, so that cm image is formed with rays emerging ~rom the prism being turned 90 relative ~o, and spaced from entering rays. In Fig. 3 Lhis is illustra~ed by the ray 24.l entering the prism emerging as a~oresaid as shown at 27 belng spaced from and at 90 to the entering ray, so that the inverted re~erted image 28 is formed at F'. The Porro 26 effectively includes a 45 reflecting means positioned as is the mirror 25 lS Fig. 2.
Fig. 4 is an end elevation of a configuration generally as Fig. 2 with a Porro type prism as 26 Fig. 3 substituted for the simple mirror reflector 25 Fig. 2.
The emerging ray 27 is spaced ~rom and at right angles to ~he entering ray as described with refer~nce to Fig. 3, the image being now formed at F' being effectively spaced ; by a distance ~A as in Fig. 2. The image is viewed by means of known ocular optics not shown in Fig. 2.
Fi~s. 5 and 6~ binocular Newtonian telescope In Fig. 5 the coniguratlon 20 Fig. 4 is shown as in Fig. ~, together with a second generally similar configuration 30 ha~ing an off-axis paraboloid reflector 31 with an optical axis 32~ a pricipal focus F', the optical axes being spaced apart and parallel. The binocular Newtonian telescope thus has two separate optical systems, namely the configurations 20 and 30, adapted for binocular observation of the images.
In Fig. 6 rays 33, 33.1 from a distant object ' ~3~3~ t~
enter paral:Lel to the axis 22, are reflecled by the paraboloid 21 as seen at 34, 34.1, pass through the Porro prism 26, and converge to form the image at F'.
In the second coniguration 30, entering rays 35, 35.1, from the distant object parallel to the optic~l axis 32 are reflected as above described and pass through a second Porro 36 forming, at F'-l, a second image oE
the distant object - a ray 37 emerging from the Porro 36 corresponding to the emerging ray 27 of the Porro 26.
An arrow 39.2 Fig. 5 represents a vertical object being viewed through the configuration 20, and an arrow 39.3 represents the same vertical object viewed through the configuration 30 The primaries 21 and 31 are each mounted in a tube (no~ shown in Figs. 5 and 6) the tubes being hinged to on~ another as indicated diagrama~ically at 41 in Fig. 5. The hinge provides means for altering separation of the parallel optical axes. In Fig. 5 it is seen that th~ emerging ray 27 is parallel to the arrow 29.2, that is to say is vertical. The Porro prism 36 and associated optic~ are mounted for rotation about the optical axis 3~ or the system 30. Thus the emerging ray 37 is adjustable for accurate parallelism with the ray 27 and this adjustment pro~ides, in combination with the hinge 41, means to alter separation of the rays 27 and 37. Range of adjustment is provided either side of 65 mm (2.5 in) being normal interpupiliary distance adjus~able as aforesaidO
A binocular telescope generally 50 has a left hand telescope assembly 51 having a tube 52 with an open ou~èr end 53. An inner end 54 has a mount assembly 55 in which the primary ~1 is adjustably mounted, as is later described, the assembly being attached to the tube . ~ .
~ 39~S ~
by screws 56-56.2. The telescope assembly 51 is a Newtonian configuration of the presen~ invention, and has an optical diagram as 20 Yig. 6.
A right telescope assembly 61 is generally similar to Lhe assembly 51, ha~ing a tube 62 with an open outer end 63, an inner end 64, a mount assembly 65 in which the off axis parabolic reflector 31 is adjustably mounted, the assembly being attached to the pri:~ms 26 and 36 are mounted respectively on - 10 the tubes 52 and 53 to be in a position as described with reference is made in the description of Fig. 5 secures the tubes 52 and 62 parallel to one another~ the hinge providing means to alter separation of the parallel tubes. Optical axes 22 and 32 of the left and right assemblies 51 and 61 respectively are shown in Fig. 7, and are adjusted for accurate parallelism by collim-ation procedure and, the optical axes being parallel, alteration o spacing between the collimated axes is eEfected by adjustment means 70 of the hinge 41, with ; 20 interocular distance being adjusted by means which have been indica~ d generally, and are described later in ` detail. The hinge 41 has an axis 71, Figs . 5, 7, and 8, and i the hinge axis be parallel to the collimated optical axes, then alteration of spacing between the optical axes does not change collimation parallelism.
Slnce, as later becomes apparent~ large alteration 1.
` ~ o~ spacing o:E the optical axes is not ordinarily required to be effected by the hinge adjustment means, parallelism :required between the hinge axis and the collimated axes is oE a lower order of precision :
than parallelism between the axes themselves e~fected ky collimation~
~ ~ 3 ~5 ~
Means to alter separation of t~e tubes ? Fi~s. 7 ancl 8 Means t~ alter separation of the tubes includes the hinge 41 and the rneans 70 to adjust the hinge.
S A fixed hinge leaf element 71-A is secured to the tube 62 as shown and hinge pin 71-P extending longitudinally through the leaf element 71-A and a second leaf element secured to the tube 52, -in 2 piano hinge like arrangement having a length about a quarter of that of the tubes~ the pin having an axis parallel to the hinge axis. Alternatively spaced binocular type hinges one adjacent each end with or without a central hinge can be used, which alternative is not shown.
The adjustment means 70, best seen in Fig. 7, includes a bracket 72 of the tube 52, a bracket 73 of the tube 62, and an adjusting screw 74 having threads 75 at an outer end, a thumbwheel 76 being mounted on the adjusting screw. An inner end of ZO the screw is received in a blind bore of the bracket 73, with a compression spring 77 surrounding the screw and bearing against opposed faces of the brackets. The threaded end 75 of the screw engaging a threaded hole of the bracket 72, rotation of the thumbwheel 76 alters separation of the tubes. With force closure by the spring, there is no backlash in the adjustment means.
: ::
, ~ 3 5 5 Means to effect Porro prism ad~ ment,_~Eæ __L_7~_~
Fig. 9 is a sub-assembly showing, in prespective, a means 80 for adjusting a Porro prism. As illustrated the numerals 26 and 36 refer to optical assemblies which include the prisms and associated viewing optics, which latter are conventional. Hereinafter terms such as "adjustment of the Porro" means adjustment, positioning, of a Porro assembly.
The Porro assembly 26 is secured in a base 81, a spindle 82 extending from an inner end 83 of the base through a journalling bracket secured to an inner side of an attachmen~ plate 84, the pla~e having dri-lled and tapped holes 85, 86 at opposite corners. The bracket, not seen in Fig. 9, is secured to the attachment plate by screws 87, 88. An ou-ter end oE the spindle 82 extends through the bracket beyond the attachment plate 84 as seen at 89 Fig. 8 only, the spindle having an axis 90.
A lever 91 is secured to the outer end.
In Fig. 7, the lever 91 is seen extending outwards through an opening in the tube 52, the attachment plate 84 (which is not seen in Fig. 7) being secured to the tube internally by ~itted screws 92 and 93 engaging the drilled and tapped holes 85, 86 of the attachment plate 84, Fig. 9.
Referring to Fig. 8, (in whlch one sub-assembly and its prism 36 has been removed) brackets secured to the tube 52 as shown have .
~ 33~ ~
opposecl ~ace elements 94, 95 which accept opposed tangent scr~ws 96 and 97 inner ends of which engage oposite faces of the lever 91 extending through the tube 52 Thus 9 tightening one tangent screw and loosening the other effects rotation of the sub-assembly 80 about the outer end of the shaft 89 Referr~lng now to Fig. 7, the tube 52 is cut to provide an openîng giving clearance to the sub-assembly 80. Fabrication is facilitated if a rectan~llar opening having ample clearance is made, a face plate 98 cut to nice clearance being provided as shown in Fig. 7. Oné prism can be fixed with one adju~table as described, although certain convenience arises when both prisms are adjustable.
Considerations with reference to adjustment ; positioning and collimation follow.
AD3USTMENT ~ND COLLIMATION
Structure :
In Fig. 5 the configuration 30 has been rotated about the hinge 41 so as to be in a posi-tion lower than the configuration 20 by an amount which is exaggerated for clarity of illustration. The ray 27 being vertical, it is seen that, notwithstanding ~ .
9 33~ D 5 rotatic)n of the configuration 30 about the hinge, the ray 37 can be made to be p~ral:Lel to the ray 27 by ro~ation of the Porro assembly 36. With the Porro prism 26 in a fixed position so th~t the ray 27 is vertical, it is seen that the hinge 41 in combination with rotation of the Porro prism 36 provides means to alter separation of the rays 27 and 37 3 that is to say provides means to adjust interocular distance ~o accomodate individual variations in interpupillary distance, this adjustment being efected withou~ materially distu~bing parallelism of the optical axes unless there be gross error in parallelism of the hinge axis 71, Fig. 7 wit~ the optical axes.
With the Porro 26 rotatable a~out F and the Porro 36 rotatable about F', it is seen that a somewhat larger range of interocular adjustment can be effected.
Provision can be made to use reflectors of small or large diameter. Suppose the reflectors 21 and 31 Fig. 5 were so large that the rays 27 and 37 could not be properly spaced as descrlbed.
In these circumstances the re~lector 21 can be mounted in a position rotated clockwise (as viewed in Fig. S) so that the optical axis is moved to a position F-A as shown. This places F-~ closer to F' compensating increased separation which, otherwise, would result from the larger diameters. Conversely, opposite rotation permits use of re1ectors of smaller diameter. Thus the possibility of mounting the reflectors wqth their axes at a sensibly constant distance apart through a large range o reflector - 14 _ 33~i5 diameters provides means for the hinge and Porro adjust~ent means aforesaid to effect interocular adjustment through a large diameter range of primary reflectors.
Consideration of the structure described shows that reflectors of diameter smaller than the smallest size ordinarily intended for serious use would not involve difEi-culty and that, as later is discussed, maximum size is limited by physical difficulty in placing one's eyes in a comfortable position ~or prolonged observation In Fig~ 7 it is seen that the parallel tubes 52 are placed one in ad-~ance of the okher so that a Line 100 joining centres o eye pieces of the observing optics is inclined as shown. This is done for comfortable viewing, in which the viewer's head is posi-tioned obliquely whilst standing beside the tubes.
~5 The reflectors 21 and 31 are moun~ed in cells, indicated at 101 and 102 in Fig. 8, of ordinary construction, the cells in turn being mounted in the tubes 52 and 62 respectively. Each primary has generally vertical and horizontal Y and X axes, not shown, these axes also being cell axes.
Usual means to effect collimation of the binocular so that the optical axes are parallel provide for ; rotation of at least one cell about the X axis and ; of at least one cell about the ~ axis.
~Means such as 99 Fig. 7-A can be used to effect collimation, the means including an assembly of a threaded stud 103 of the cell 102 extending through an outer end 65.1 of the mo~nting assembly 65 and through a compression spring between the is cell and the mounting, the stud hc7ving an external nut 104 as sh~wn. The stud 103 beir-g adjacent ~ne end of the Y axis, with an additional assembly (not shown~ adjacent an opposite end Df the Y axis and adjacent each end o~ the X axis, it is seen that the means 99 e~fect collimation as aforesaid by adjustment of the nuts~ As is knownl adjustment c~n ~e effec~ed by three means 99 at 120 , and in equivalent ways The particular means used to effect parallelism o~ the axis is unimportant~
In Fig. 2, ~A is exaggerated for clarity, accordingly ~' is shown at an exaggerated clistance from the optical axis 22. In practice F' is much ; closer than shown With a simple 45 mirror 25 being used, the positioning of the mirror is determined by a value assigned to ~A. The 45 mirror 25 Fig. 2, should be positioned so that the reflected ray 24, considered as being an outs~ e ray of the pencil, strikes the mirror If this is not the case, ~20 there will be light loss since some of the outside rays would not be re1ected by the mirror~ Since the mirror has a si~e large~ than required to intercept the out-side rays, it is seen that the positioning has only to be such that oltside rays of the pencil are intercepted.
In Figo 3, the ray 24.1 is an axial ray and~ analagously to positioning of the mirror 25, there is latitude in posi~ioning of t~e prism. I~ has b~en poin~ed ou~ that axial rays and some paraxlal ray~ are blocked. Position-ing is nevertheless axial, or substantially axial. It :
~ 3~5 ~
is required that both prisms be locate~ as descrii)ed a~ove, but some inaccuracy can be toler~ted, the limit being that owter rays of the pencil1 when reflected by the primary~ impinge upon the prism since the Porro prism effectively includes a 45 mlrror coming within the description of the mirror 25 Figs. 2, effec~ing minimal block~ge.
Procedure Procedure following refers to a Newtonian binocular telescope as described with reference to Fig. 7, the telescope having circular off axis paraboloid reflectors of outslde diameter of 6 inchesg and of 36 l~ch focal length.
In the exemplified telescope the beam has 3 travel of about three inches through the Porros, and in manufacture provision has been made ~or such travel taking into consideration the focal length of the refleetors. The Porros have an e~fective axis, in Fig. 8 the effective axis of the Porro 26 2d is taken as the axis 90 of the spindle, so that when the tangent sere~s 96 and 97 are moved, the Porro r~tates about this axis i~q marked F and lies substantially in the optical axis of eaeh configuration ie. within the toleranee above. A ~idueial mark (not shown) is pro-vlded on the eell of eaeh ref~ee~or and eaeh refleetor has been so mounte~ that lts o~Ical axis is ali~ned with a radius throug~ ~h~ fldueial mark. T~us the effective axis of each Por_o assembly is properly located.
~e~erring to Fig. 7, heek that the tubes ~ 3~j~
52 and 62 are nic~ly aligned and par11Lel, and that the hinge works smooth]y when the th~mbwheel 76 is turned. In a telescope of this size rwn of about five eighths of an inch is satisfclctory. Set the thum~wheel in the middle of its run. Adjust the interocular distance. With the thumbwheel centered and the rays 27, 37 Fig. 5 parallel interocular distance should be 65 mm, adjust if necessary. Place the telescope on an optical bench, and look through the eye pieces 106, 107 Fig. 7. Most likely two separate images of the mirrors will be seen appearing as two separate discs. It is required that the two discs merge to one, and be centered in the field of view, when correctly set two prism faces are seen Now sight the binocular at a clearly defined distant object, ~robably a different portion of the object will appear in each eye piece due to small misalignment of the optical axes, This is corrected by slight adjustment of the X and Y
adjustment means of one (or of both) tubesO The Y axis Deing in a vertical plane, movement of rotation of a reflector about the Y axis will increase or decrease separation of the image9 With the images 25~ aligned7 movement of one mirror a~out the X axis a which is at right angles to the Y axis, will effect coinci-dence of the im~ges, the telescope then being ready for use and adiusted for an i~terpupillary distance according to that of the particular user.
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It is seen that adjustment of interocular distance is re~dily effected by means of the thumb screw 76, and as explained this adjustrnent does noL
materially effect parallelism of the optical axes.
When the thumb screw is adjusted to increase or decrease interocular distance, see now Fig. 5, the rays 27 and 37 are no longer parallel. Parallelism is recovered by a slight re-ad;justment of the tangent screws 96, 97.
Alternative confi~u_ation_~g~ 10 11 An alternative configuration 110 has a primary paraboloid reflector 111 off axis by an amount S, the optical axis being designated 112.
The re~lecting means 15 is spaced inwards of the principal focus F a distance ~A-l. An entering paraxialpencil 113 of rays from a distant object is reflected by the primary and i uninterrupted would, as before, form an image at F. The reflecting means 15 intercepts the converging rays so that the image is formed at F'.
The reflecting means 15 a depth projected on a plane normal to the entering pencil, normal to the optical axis, i.e. as seen in Fig. 11 and designated B, hereinafter blocking depth.
~A-l being such that all the reflected rays are intlercepted by the mirror, when S is equal to or greater than the blocking depth, there is no blockage of the entering pencil and the minimal blockage now becomes zero. The reflecting :. - ' . . .. .
means having ~ blocking depth B as aforesaid~ and the spacing ~A-l being as aforesaid, are thus means to effect that the minimal blocking is zero.
The configuration, or optical system, llO is thus characteri~ed by an of~-axis primary paraboloid having an off axis distance, S, equal to or greater than the blocking clepth~ B, of the reflecting means 15.
Binocular without blocka~e An off-axis primary paraboloid characterized as above is shown in broken outline at 111 in Fig. 4.
In Fig. 5 primaries so characterized a~e shown in broken outline at 114 and 115, the broken outline primaries here being of smaller diame~er than the primaries 21 and 31.
In a binocular telescope having two optical systems so characterized, but otherwise within the descriptions of Figs. 5 - 9, all rays of a paraxial pencil as the pencil 113 Fig. 10 thus enter and are reflected with no blockage loss.
Referring to Figs. 7 and 8, the tubes have inside diameters to accept the cells 101, 102. In a no blockage exemplification, the cells are of the same diameter ~with primaries of the same diameter~
but the tubes have an inside diameter larger by the off axis distance S. The no blockage exemplification is otherwise within the descriptions given.
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Field of the invention The inven~ion relates to a binocular telescope having two modiEied Newtonian viewing systems, being adapted materially to reduoe, and in one exempliication to eliminate, light blockage which is characteristic of a Newtonian telescope.
Prior art A common Newtonian telescope has a paraboloid reflector converging a parallel entering pencil to a principal focus which, if uninterrupted, would be on the optical axis. A forty-five degree reflector, which can be a front surface mirror, is placed generally central of the optical axis and spaced inwards from the principal focus towards the reflec~or by a distance in excess o~ half the diameter of the primary so as to intercept the converging reflected rays to form an image clear of the entering pencil.
As is well known, a Newtonian telescope has many advantages, and has a major disadvantage in that the reflecting mirror results in blockage of entering rays.
;~ 25 Canadian Patent 768,402 issued 2~ March 1964 to the present inventer, and equivalent foreign patents and applications, teach a Newtonian conig-uration using a half re1ector of generally semicircular orm. As is later explained in detail, the hal~
reflector has an optical axis su~stantially on a diametric cord forming an edge of the hal reflector.
3 3 ~c~j Th~ls a very ~n~lch smaller re:~lector can be used with consequent materi~l recluction of blockage.
OUTLIN~ OF THE INVEMTION
The present invention provides a Newtonian optical system with an off-axis primary reflector having an optical axis adjacent to an edge, conse-quently light blockage can be materially reduced and, in one exemplif:ication, eliminate~l. ..
A binocular telescope according to the present invention provides a left hand optical system with an off-axis parabolic reflector, and a reflecting means on the optical axis placed inwards from the principal focus towards the primary by a distance such as to intercept the reflected rays so that an image of a distant object is formed clear o the entering rays, viewing optics being provided to observe the image. A right hand optical system similar to the left hand optical system is provided, the two systems being constructed and arranged for binocular observation of the images. Means are provided to effect collimation o the binocular so that the optical axes o each system are parallel, : and means are provided to adjust the interocular distance of viewing optices so as to accommodate individual variation in interpupilliary distance without ~: materially~disturbing the parallism of the optical - axes.
In one exemplification of a binocular ~: telescope according to the present invention the of-: 30 axis primaries have off axis distances equal to or greater than an amount by which the re1ecting means ~ would, otherwise, block rays of the entering pencil, : . - 3 -, 335~
so thlt all of the rays of the pencil enter ancl are re flected by ~he off-axis primary, and are intercepted by ~he reflecting means, wi~hout blockage~
A detailed description following related to drawings gives exempli~ication of the present invention which, ho-~ever, is capable of expression in structure other than that particularly described and illustrated, DESCRIPTION OF THE DRAWINGS
Fig. 1 is an optical diagram o a prior art Newtonian re1ecting telescope, FigJ 2 is an optical,diagram illustrating a principle of the present invention, Fig. 3 is a detail perspective diagram of a known Porro type prism, Fig. 4 is an end elevation of a configuration gene-rally as Fig~ 2 seen from 4-4 of Fig. 2, and having a prism according to Fîg. 3~
Fig. 5 shows a first configuration as Fig. 4 with a second coniguration generally similar to the first configuration, the configurations ; ~orming a Newtonian binocular exemplary o~ the the present invention9 some adjustment para-meters being exaggerated for clarity, Fig. 6 is a light ray diagram of the embodiment of Fig. 5 Figso 1 through 6 are diagrammetrlc~
Fig~ 7 is a top perspective o a Newtonian binocular telescope having an optical diagram as Fig~
~30 6, ;;; - 4 -.
~ ~ 39~5 ~
Fig. 7-A is a fragmented elevation of a mounting assembly partly broken away to show a collimation adjustment means, ; 5 Fig. 8 is a perspective of the telescope of Fig. 7 seeo from 8-8 Fig, 7, Fig. 9 i5 a detail perspective of a Porro prism assembly showing adjusting means, Fig. 10 is an optical diagram illus~rating an alternative embodiment without obstruction ~o an entering pencil, Fig. 11 is an end elevation of the alternative embodiment seen from XI-XI Fig. 10, Figs. 10 and ll are diagrammatic.
`:
DETAIL DISCLOSURE
Prior Art Prior art is discussed in some detail below, in order to distinguish Canadian patent 768 ,402 aforesaid fr~m the structure of the presen~ invention.
.
The Canadian patent is also discu~sed in detail sufficient to show how the present invention distinguishes over~structure accordin~ to the : : ~
patent.
.
~33~
Prror Art Newto arl, Fl~. 1 Fig. 1 which is prior a-rt, is a diagram o~ a Newtonian reflecting telescope. The telescope 10 has a primary paraboloid re1ector 11, ~f diameter D,having ~n optical axis 12, with a prirlcipal focus F on the optical axis at a dis~ance from the primary reflector equal to its focal length. Ent:ering rays 139 13.1 from a distant object are parallel t:o the axis, striking the primary. The entering rays are reflected as seen at 14~ not interrupted, the reflected rays converge to focus at F. A 45 reflector 15 on the optical axis, spaced a distance A inwards towards the primary, A as seen being ~omewhat greater than D/2, causes the rays to converge at F' forming an inverted image of the distant object, F' being clear of the entering rays. A exceeds D/2 by a clearance ~A, Fig. 1. The image is observed by a suitable objective system, the re~lector 15 is commonly a plane ront surfaced mirror.
Canadian patent 768,402 issued 24 March 1964 to the present inventor, and equivalent foreign patents and applications, ~each a Newtonian configuration using a half reflector of generally semi-circular form. In prior known constructions such as illustrated in Fig. 1, the 45 reflector lS is spa ed inwards in the optical axis a distance in excess of D/2 so that Fl is clear of the entering rays, as explained~ In a con~iguration according~to the patent aforesaid9 the half reflector has an optical axis substantially on a diametric cord orming one edge of the half reflector.
The distance measured along the optical axis from F to the mirror l5 is designated A in Fig. 1, where A is greater than D/2 by the amount ~a. As is well known, blockage and consequently loss of light occur ~ ~ 3 ~ 5 from obstruct:ion causecl by the 45 mirror 15, which obstr~lction increases with increase of diameter of the reflector, focal length remaining constan~. It is clear that, in a construction according to the patent above, since the optical axis of the half reflector lies along an axial edge oE a pencil of parallel entering rays, A can be greatly reduced to AA with consequent reduction in blockage.
Fi~. 2, off axis Newtonian Fig. 2 is a diagram to illustrate a principle of the present invention, being also a Newtonian configuration. In Fig. 2 a telescope configuration, an optical diagram of which is designated generally 20, has an off-axis paraboloid primary reflector 21 having an optical axis 22 and a principal focus F, with the optical axis being at an edge o~ the primary. Entering rays 23, 23.1 of a pencil of rays parallel to the axis are reflected as seen at 24 and 24.1 and would, if uninter-rupted, converge at the principal focus F, the entering ray 23.1 and the reflected ray 24.1 being axial. In Figs. 1 and 2, F' is clear of the entering pencil.
Clearance is exaggerated in Fig. 1 and 2 for clarity.
Consequently with a reflecting means, namely a 45 mirror 259 placed on the optical axis 22 an image is formed at F' as before, but the 45 mirror 25 need only be spaced inwards by the distance ~A, ~A being very m~lch smaller than A Fig. 1. Thus there is minimal light blockage since the mirror 25 can be smaller than the mirror 15 in a ratio ~AjA. In Fig. 2, the entering and reflected axial rays 23.1 and 24.1, and adjacent paraxial rays are, in actuality blocked by the mirror 25, and these rays not reflected as shown. Image formation in Fig. ~ is shown thus conventionally or clarity, and is so shown ~, .
~ 3 3~j~
succeeding figwres. The optical axis is seen to be within the blockage.
Figs. 3 and 4 Fig. 3 is a detail perspective diagram of a Porro type prism 26 of a well Icnown kind, wherein li~ht is totally reflected inside two 45-90 prisms at right angles to each other, so that cm image is formed with rays emerging ~rom the prism being turned 90 relative ~o, and spaced from entering rays. In Fig. 3 Lhis is illustra~ed by the ray 24.l entering the prism emerging as a~oresaid as shown at 27 belng spaced from and at 90 to the entering ray, so that the inverted re~erted image 28 is formed at F'. The Porro 26 effectively includes a 45 reflecting means positioned as is the mirror 25 lS Fig. 2.
Fig. 4 is an end elevation of a configuration generally as Fig. 2 with a Porro type prism as 26 Fig. 3 substituted for the simple mirror reflector 25 Fig. 2.
The emerging ray 27 is spaced ~rom and at right angles to ~he entering ray as described with refer~nce to Fig. 3, the image being now formed at F' being effectively spaced ; by a distance ~A as in Fig. 2. The image is viewed by means of known ocular optics not shown in Fig. 2.
Fi~s. 5 and 6~ binocular Newtonian telescope In Fig. 5 the coniguratlon 20 Fig. 4 is shown as in Fig. ~, together with a second generally similar configuration 30 ha~ing an off-axis paraboloid reflector 31 with an optical axis 32~ a pricipal focus F', the optical axes being spaced apart and parallel. The binocular Newtonian telescope thus has two separate optical systems, namely the configurations 20 and 30, adapted for binocular observation of the images.
In Fig. 6 rays 33, 33.1 from a distant object ' ~3~3~ t~
enter paral:Lel to the axis 22, are reflecled by the paraboloid 21 as seen at 34, 34.1, pass through the Porro prism 26, and converge to form the image at F'.
In the second coniguration 30, entering rays 35, 35.1, from the distant object parallel to the optic~l axis 32 are reflected as above described and pass through a second Porro 36 forming, at F'-l, a second image oE
the distant object - a ray 37 emerging from the Porro 36 corresponding to the emerging ray 27 of the Porro 26.
An arrow 39.2 Fig. 5 represents a vertical object being viewed through the configuration 20, and an arrow 39.3 represents the same vertical object viewed through the configuration 30 The primaries 21 and 31 are each mounted in a tube (no~ shown in Figs. 5 and 6) the tubes being hinged to on~ another as indicated diagrama~ically at 41 in Fig. 5. The hinge provides means for altering separation of the parallel optical axes. In Fig. 5 it is seen that th~ emerging ray 27 is parallel to the arrow 29.2, that is to say is vertical. The Porro prism 36 and associated optic~ are mounted for rotation about the optical axis 3~ or the system 30. Thus the emerging ray 37 is adjustable for accurate parallelism with the ray 27 and this adjustment pro~ides, in combination with the hinge 41, means to alter separation of the rays 27 and 37. Range of adjustment is provided either side of 65 mm (2.5 in) being normal interpupiliary distance adjus~able as aforesaidO
A binocular telescope generally 50 has a left hand telescope assembly 51 having a tube 52 with an open ou~èr end 53. An inner end 54 has a mount assembly 55 in which the primary ~1 is adjustably mounted, as is later described, the assembly being attached to the tube . ~ .
~ 39~S ~
by screws 56-56.2. The telescope assembly 51 is a Newtonian configuration of the presen~ invention, and has an optical diagram as 20 Yig. 6.
A right telescope assembly 61 is generally similar to Lhe assembly 51, ha~ing a tube 62 with an open outer end 63, an inner end 64, a mount assembly 65 in which the off axis parabolic reflector 31 is adjustably mounted, the assembly being attached to the pri:~ms 26 and 36 are mounted respectively on - 10 the tubes 52 and 53 to be in a position as described with reference is made in the description of Fig. 5 secures the tubes 52 and 62 parallel to one another~ the hinge providing means to alter separation of the parallel tubes. Optical axes 22 and 32 of the left and right assemblies 51 and 61 respectively are shown in Fig. 7, and are adjusted for accurate parallelism by collim-ation procedure and, the optical axes being parallel, alteration o spacing between the collimated axes is eEfected by adjustment means 70 of the hinge 41, with ; 20 interocular distance being adjusted by means which have been indica~ d generally, and are described later in ` detail. The hinge 41 has an axis 71, Figs . 5, 7, and 8, and i the hinge axis be parallel to the collimated optical axes, then alteration of spacing between the optical axes does not change collimation parallelism.
Slnce, as later becomes apparent~ large alteration 1.
` ~ o~ spacing o:E the optical axes is not ordinarily required to be effected by the hinge adjustment means, parallelism :required between the hinge axis and the collimated axes is oE a lower order of precision :
than parallelism between the axes themselves e~fected ky collimation~
~ ~ 3 ~5 ~
Means to alter separation of t~e tubes ? Fi~s. 7 ancl 8 Means t~ alter separation of the tubes includes the hinge 41 and the rneans 70 to adjust the hinge.
S A fixed hinge leaf element 71-A is secured to the tube 62 as shown and hinge pin 71-P extending longitudinally through the leaf element 71-A and a second leaf element secured to the tube 52, -in 2 piano hinge like arrangement having a length about a quarter of that of the tubes~ the pin having an axis parallel to the hinge axis. Alternatively spaced binocular type hinges one adjacent each end with or without a central hinge can be used, which alternative is not shown.
The adjustment means 70, best seen in Fig. 7, includes a bracket 72 of the tube 52, a bracket 73 of the tube 62, and an adjusting screw 74 having threads 75 at an outer end, a thumbwheel 76 being mounted on the adjusting screw. An inner end of ZO the screw is received in a blind bore of the bracket 73, with a compression spring 77 surrounding the screw and bearing against opposed faces of the brackets. The threaded end 75 of the screw engaging a threaded hole of the bracket 72, rotation of the thumbwheel 76 alters separation of the tubes. With force closure by the spring, there is no backlash in the adjustment means.
: ::
, ~ 3 5 5 Means to effect Porro prism ad~ ment,_~Eæ __L_7~_~
Fig. 9 is a sub-assembly showing, in prespective, a means 80 for adjusting a Porro prism. As illustrated the numerals 26 and 36 refer to optical assemblies which include the prisms and associated viewing optics, which latter are conventional. Hereinafter terms such as "adjustment of the Porro" means adjustment, positioning, of a Porro assembly.
The Porro assembly 26 is secured in a base 81, a spindle 82 extending from an inner end 83 of the base through a journalling bracket secured to an inner side of an attachmen~ plate 84, the pla~e having dri-lled and tapped holes 85, 86 at opposite corners. The bracket, not seen in Fig. 9, is secured to the attachment plate by screws 87, 88. An ou-ter end oE the spindle 82 extends through the bracket beyond the attachment plate 84 as seen at 89 Fig. 8 only, the spindle having an axis 90.
A lever 91 is secured to the outer end.
In Fig. 7, the lever 91 is seen extending outwards through an opening in the tube 52, the attachment plate 84 (which is not seen in Fig. 7) being secured to the tube internally by ~itted screws 92 and 93 engaging the drilled and tapped holes 85, 86 of the attachment plate 84, Fig. 9.
Referring to Fig. 8, (in whlch one sub-assembly and its prism 36 has been removed) brackets secured to the tube 52 as shown have .
~ 33~ ~
opposecl ~ace elements 94, 95 which accept opposed tangent scr~ws 96 and 97 inner ends of which engage oposite faces of the lever 91 extending through the tube 52 Thus 9 tightening one tangent screw and loosening the other effects rotation of the sub-assembly 80 about the outer end of the shaft 89 Referr~lng now to Fig. 7, the tube 52 is cut to provide an openîng giving clearance to the sub-assembly 80. Fabrication is facilitated if a rectan~llar opening having ample clearance is made, a face plate 98 cut to nice clearance being provided as shown in Fig. 7. Oné prism can be fixed with one adju~table as described, although certain convenience arises when both prisms are adjustable.
Considerations with reference to adjustment ; positioning and collimation follow.
AD3USTMENT ~ND COLLIMATION
Structure :
In Fig. 5 the configuration 30 has been rotated about the hinge 41 so as to be in a posi-tion lower than the configuration 20 by an amount which is exaggerated for clarity of illustration. The ray 27 being vertical, it is seen that, notwithstanding ~ .
9 33~ D 5 rotatic)n of the configuration 30 about the hinge, the ray 37 can be made to be p~ral:Lel to the ray 27 by ro~ation of the Porro assembly 36. With the Porro prism 26 in a fixed position so th~t the ray 27 is vertical, it is seen that the hinge 41 in combination with rotation of the Porro prism 36 provides means to alter separation of the rays 27 and 37 3 that is to say provides means to adjust interocular distance ~o accomodate individual variations in interpupillary distance, this adjustment being efected withou~ materially distu~bing parallelism of the optical axes unless there be gross error in parallelism of the hinge axis 71, Fig. 7 wit~ the optical axes.
With the Porro 26 rotatable a~out F and the Porro 36 rotatable about F', it is seen that a somewhat larger range of interocular adjustment can be effected.
Provision can be made to use reflectors of small or large diameter. Suppose the reflectors 21 and 31 Fig. 5 were so large that the rays 27 and 37 could not be properly spaced as descrlbed.
In these circumstances the re~lector 21 can be mounted in a position rotated clockwise (as viewed in Fig. S) so that the optical axis is moved to a position F-A as shown. This places F-~ closer to F' compensating increased separation which, otherwise, would result from the larger diameters. Conversely, opposite rotation permits use of re1ectors of smaller diameter. Thus the possibility of mounting the reflectors wqth their axes at a sensibly constant distance apart through a large range o reflector - 14 _ 33~i5 diameters provides means for the hinge and Porro adjust~ent means aforesaid to effect interocular adjustment through a large diameter range of primary reflectors.
Consideration of the structure described shows that reflectors of diameter smaller than the smallest size ordinarily intended for serious use would not involve difEi-culty and that, as later is discussed, maximum size is limited by physical difficulty in placing one's eyes in a comfortable position ~or prolonged observation In Fig~ 7 it is seen that the parallel tubes 52 are placed one in ad-~ance of the okher so that a Line 100 joining centres o eye pieces of the observing optics is inclined as shown. This is done for comfortable viewing, in which the viewer's head is posi-tioned obliquely whilst standing beside the tubes.
~5 The reflectors 21 and 31 are moun~ed in cells, indicated at 101 and 102 in Fig. 8, of ordinary construction, the cells in turn being mounted in the tubes 52 and 62 respectively. Each primary has generally vertical and horizontal Y and X axes, not shown, these axes also being cell axes.
Usual means to effect collimation of the binocular so that the optical axes are parallel provide for ; rotation of at least one cell about the X axis and ; of at least one cell about the ~ axis.
~Means such as 99 Fig. 7-A can be used to effect collimation, the means including an assembly of a threaded stud 103 of the cell 102 extending through an outer end 65.1 of the mo~nting assembly 65 and through a compression spring between the is cell and the mounting, the stud hc7ving an external nut 104 as sh~wn. The stud 103 beir-g adjacent ~ne end of the Y axis, with an additional assembly (not shown~ adjacent an opposite end Df the Y axis and adjacent each end o~ the X axis, it is seen that the means 99 e~fect collimation as aforesaid by adjustment of the nuts~ As is knownl adjustment c~n ~e effec~ed by three means 99 at 120 , and in equivalent ways The particular means used to effect parallelism o~ the axis is unimportant~
In Fig. 2, ~A is exaggerated for clarity, accordingly ~' is shown at an exaggerated clistance from the optical axis 22. In practice F' is much ; closer than shown With a simple 45 mirror 25 being used, the positioning of the mirror is determined by a value assigned to ~A. The 45 mirror 25 Fig. 2, should be positioned so that the reflected ray 24, considered as being an outs~ e ray of the pencil, strikes the mirror If this is not the case, ~20 there will be light loss since some of the outside rays would not be re1ected by the mirror~ Since the mirror has a si~e large~ than required to intercept the out-side rays, it is seen that the positioning has only to be such that oltside rays of the pencil are intercepted.
In Figo 3, the ray 24.1 is an axial ray and~ analagously to positioning of the mirror 25, there is latitude in posi~ioning of t~e prism. I~ has b~en poin~ed ou~ that axial rays and some paraxlal ray~ are blocked. Position-ing is nevertheless axial, or substantially axial. It :
~ 3~5 ~
is required that both prisms be locate~ as descrii)ed a~ove, but some inaccuracy can be toler~ted, the limit being that owter rays of the pencil1 when reflected by the primary~ impinge upon the prism since the Porro prism effectively includes a 45 mlrror coming within the description of the mirror 25 Figs. 2, effec~ing minimal block~ge.
Procedure Procedure following refers to a Newtonian binocular telescope as described with reference to Fig. 7, the telescope having circular off axis paraboloid reflectors of outslde diameter of 6 inchesg and of 36 l~ch focal length.
In the exemplified telescope the beam has 3 travel of about three inches through the Porros, and in manufacture provision has been made ~or such travel taking into consideration the focal length of the refleetors. The Porros have an e~fective axis, in Fig. 8 the effective axis of the Porro 26 2d is taken as the axis 90 of the spindle, so that when the tangent sere~s 96 and 97 are moved, the Porro r~tates about this axis i~q marked F and lies substantially in the optical axis of eaeh configuration ie. within the toleranee above. A ~idueial mark (not shown) is pro-vlded on the eell of eaeh ref~ee~or and eaeh refleetor has been so mounte~ that lts o~Ical axis is ali~ned with a radius throug~ ~h~ fldueial mark. T~us the effective axis of each Por_o assembly is properly located.
~e~erring to Fig. 7, heek that the tubes ~ 3~j~
52 and 62 are nic~ly aligned and par11Lel, and that the hinge works smooth]y when the th~mbwheel 76 is turned. In a telescope of this size rwn of about five eighths of an inch is satisfclctory. Set the thum~wheel in the middle of its run. Adjust the interocular distance. With the thumbwheel centered and the rays 27, 37 Fig. 5 parallel interocular distance should be 65 mm, adjust if necessary. Place the telescope on an optical bench, and look through the eye pieces 106, 107 Fig. 7. Most likely two separate images of the mirrors will be seen appearing as two separate discs. It is required that the two discs merge to one, and be centered in the field of view, when correctly set two prism faces are seen Now sight the binocular at a clearly defined distant object, ~robably a different portion of the object will appear in each eye piece due to small misalignment of the optical axes, This is corrected by slight adjustment of the X and Y
adjustment means of one (or of both) tubesO The Y axis Deing in a vertical plane, movement of rotation of a reflector about the Y axis will increase or decrease separation of the image9 With the images 25~ aligned7 movement of one mirror a~out the X axis a which is at right angles to the Y axis, will effect coinci-dence of the im~ges, the telescope then being ready for use and adiusted for an i~terpupillary distance according to that of the particular user.
.
,' ' , ~
~33t~
It is seen that adjustment of interocular distance is re~dily effected by means of the thumb screw 76, and as explained this adjustrnent does noL
materially effect parallelism of the optical axes.
When the thumb screw is adjusted to increase or decrease interocular distance, see now Fig. 5, the rays 27 and 37 are no longer parallel. Parallelism is recovered by a slight re-ad;justment of the tangent screws 96, 97.
Alternative confi~u_ation_~g~ 10 11 An alternative configuration 110 has a primary paraboloid reflector 111 off axis by an amount S, the optical axis being designated 112.
The re~lecting means 15 is spaced inwards of the principal focus F a distance ~A-l. An entering paraxialpencil 113 of rays from a distant object is reflected by the primary and i uninterrupted would, as before, form an image at F. The reflecting means 15 intercepts the converging rays so that the image is formed at F'.
The reflecting means 15 a depth projected on a plane normal to the entering pencil, normal to the optical axis, i.e. as seen in Fig. 11 and designated B, hereinafter blocking depth.
~A-l being such that all the reflected rays are intlercepted by the mirror, when S is equal to or greater than the blocking depth, there is no blockage of the entering pencil and the minimal blockage now becomes zero. The reflecting :. - ' . . .. .
means having ~ blocking depth B as aforesaid~ and the spacing ~A-l being as aforesaid, are thus means to effect that the minimal blocking is zero.
The configuration, or optical system, llO is thus characteri~ed by an of~-axis primary paraboloid having an off axis distance, S, equal to or greater than the blocking clepth~ B, of the reflecting means 15.
Binocular without blocka~e An off-axis primary paraboloid characterized as above is shown in broken outline at 111 in Fig. 4.
In Fig. 5 primaries so characterized a~e shown in broken outline at 114 and 115, the broken outline primaries here being of smaller diame~er than the primaries 21 and 31.
In a binocular telescope having two optical systems so characterized, but otherwise within the descriptions of Figs. 5 - 9, all rays of a paraxial pencil as the pencil 113 Fig. 10 thus enter and are reflected with no blockage loss.
Referring to Figs. 7 and 8, the tubes have inside diameters to accept the cells 101, 102. In a no blockage exemplification, the cells are of the same diameter ~with primaries of the same diameter~
but the tubes have an inside diameter larger by the off axis distance S. The no blockage exemplification is otherwise within the descriptions given.
....
:
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1 A binocular reflecting telescope including (a) A left hand optical system having (i) an off axis parabolic primary reflector having an optical axis and a principal focus, and being adapted to reflect an entering pencil of paraxial rays, the rays being from a distant object, to converge at the principal focus, (ii)a reflecting means on the optical axis spaced inwards from the principal focus towards the primary reflector by a distance such as to intercept the reflected rays so that an image of the distant object is formed clear of the entering rays, (iii)and means to observe the image, (b) a right hand optical system similar to the left hand optical system, adapted for binocular observation of the images, (c) means to effect collimation of the binocular so that the optical axes are parallel, (d) means to adjust interocular distance to accomodate individual variations in inter-pupillary distance, constructed and arranged for minimal blockage of the entering rays by the reflecting means.
2. A telescope as defined in claim 1, wherein the means to observe the image includes a Porro prism assembly having an effective axis which lies substantially in the optical axis, the prism assembly including viewing optics.
3. A telescope according to claim 2, wherein the binocular telescope includes (e) parallel tubes each having an open outer end and inner ends with mounting assemblies at the inner ends, a primary reflector being mounted in each mounting assembly.
4. A telescope as defined in claim 3, wherein the means (c) to effect collimation of the binocular includes, (i) cells of the mounting assemblies, the primary reflectors being mounted in the cells, the primary reflectors each having generally vertical and horizontal Y and X axes these axes being also cell axes, (ii) means to rotate at least one cell about its X axis, and means to rotate at least one cell about its Y axis.
5. A telescope according to claim 4, wherein the means (d) to adjust interocular distance includes (i) hinge means for altering separation of the para-llel tubes, the hinge having an axis parallel to the optical axes, (ii) a means for adjusting a Porro prism assembly.
6. A telescope according to claim 5, wherein the hinge means for altering separation of the parallel tubes includes means to adjust the hinge including; a fixed leaf element secured to each tube; a hinge pin extending longitudinally therethrough; a bracket secured to each tube; and adjusting screw in operative engagement with the brackets, with a compression spring surrounding the screw and bearing against opposed faces of the brackets; adapted for rotation of a thumbwheel to alter separation of the tubes.
7. A telescope according to claim 6, wherein the means for adjusting a Porro prism assembly includes means to rotate the assembly about its effective axis.
8. A telescope according to claim 3 and (f) means to effect that the minimal blocking is zero.
9. A telescope according to claim 8, the reflecting means having a depth projected on a plane normal to optical axis, being a blocking depth, each system being characterized by, (g) an off axis primary paraboloid being off axis by a distance equal to or greater than the blocking depth, (h) and the reflecting means being spaced inwards as aforesaid by a distance such that all of the rays reflected by the primary reflector are intercepted by the reflecting means and brought to focus as aforesaid.
10. A telescope according to claim 7, the reflecting means having a depth projected on a plane normal to optical axis, being a blocking depth, each system be m g characterized by, (g) an off axis primary paraboloid being off axis by a distance equal to or greater than the blocking depth, (h) and the reflecting means being spaced inwards as aforesaid by a distance such that all of the rays reflected by the primary reflector are intercepted by the reflecting means and brought to focus as aforesaid, adapted to effect that the minimal blocking is zero.
11. A telescope as claimed in Claim 2 wherein the means (iii) to observe the image include:
(a) a pair of eye pieces, each eye piece having a central optical axis, the eye pieces being positioned so that a line joining the centers of the eye pieces is inclined to the optical axes 50 as to improve viewing comfort.
(a) a pair of eye pieces, each eye piece having a central optical axis, the eye pieces being positioned so that a line joining the centers of the eye pieces is inclined to the optical axes 50 as to improve viewing comfort.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA290,234A CA1093355A (en) | 1977-11-04 | 1977-11-04 | Binocular telescope with off axis reflectors |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA290,234A CA1093355A (en) | 1977-11-04 | 1977-11-04 | Binocular telescope with off axis reflectors |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1093355A true CA1093355A (en) | 1981-01-13 |
Family
ID=4109954
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA290,234A Expired CA1093355A (en) | 1977-11-04 | 1977-11-04 | Binocular telescope with off axis reflectors |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1093355A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0601565A2 (en) * | 1992-12-10 | 1994-06-15 | Shuichi Masunaga | Binocular reflecting telescope |
-
1977
- 1977-11-04 CA CA290,234A patent/CA1093355A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0601565A2 (en) * | 1992-12-10 | 1994-06-15 | Shuichi Masunaga | Binocular reflecting telescope |
| EP0601565A3 (en) * | 1992-12-10 | 1995-03-01 | Shuichi Masunaga | Binocular reflecting telescope. |
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