Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
  • G02B17/02—Catoptric systems, e.g. image erecting and reversing system
• • 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

Definitions

• the present invention comprises a way to arrange the light path in a monocular, binocular or similar instrument, to obtain in practice an instrument as compact and ergonomical as possible, at the same time as best possible optical data are maintained and the internal mirrors can be given smallest dimensions.
• the light path is located near a plane, but at least two of the image erecting mirrors are located on each side of this plane. The light from the objective strikes these two mirrors in turn, and falling lines are avoided by inclining the intersection line for said two mirrors to said plane.
• Image erection takes place in most telescopes in the conventional manner via the first Porro system.
• a disadvantage with this system is that the telescope cannot be made very compact when the objective focal length is high.
• image erection by means of a lens between objective and ocular is also known.
• the disadvantage with this, is that the instrument becomes very long, at the same time as the image erecting lens may introduce aberrations.
• the instument casing may be rather wide which makes gripping with both hands easy, but the length should not exceed the width by any greater value; ot ⁇ herwise the ergonomy becomes reduced. At the same time ought the height of the instrument be as small as possible.
• fig 1 shows the light path of the instrument in perspective
• fig 2 shows an end wiew and fig 3 shows a wiew in elevation
• fig 4 shows a wiew from the above
• fig 5 shows a tunnel diagram of the light path
• fig 6a shows, in elevation, an irregular instrument casing
• fig 6b shows, in elevation, the symmetry which is made possible for an instrument with a light path according to the invention.
• the central ray (CS from now on) is defined as a to telescope 7 entering light ray, which before entrance into the instrument is coaxial with the optical axis for objective 6.
• Central ray CS passes objective 6, is reflected in mirrors 1 , 2, 3, and 4 in turn, before it finally exits through ocular 5.
• the ocular optic axis is for best results, according to normal optic design rules, coaxial with exiting central ray CS.
• Through ocular 5 can an erect image be seen, precisely as in a conventional telescope.
• the reflecting plane for mirror 1 is from now on designated 1 '
• the reflecting plane for mirror 2 is designated 2 ', for mirror 3, 3 ', and for mirror 4, 4 ' .
• Plane SP contains the optic axis for objective 6, and a point P, located precisely between the points where central ray CS strikes mirror 2 and 3, respectively.
• the telescope casing 8 can preferably be made symmetrical with regard to plane SP.
• the ocular optic axis is in the described case, but need not be, parallel with the optic axis for objective 6. All optical elements are normally secured to casing 8.
• the border lines BL1 and BL2 are attained by optical dimensioning, in fig 5. Every one of the mirrors 1 -4 must be dimensioned so large so they reach from line BL1 to BL2 in the tunnel diagram, to make sure that at least 50% of the light from objective 6 reaches the field stop, and all of the light from the objective reaches the field center.
• the distance between mirror 1 and objective 6 in essence determines the overall length of the telescope.
• L the distance between mirror 1 and objective 6
• L the distance between mirror 1 and objective 6
• the tunnel diagram in fig 5 shows that the distance between the lines BL1 and BL2 is small, far away from objective 6.
• the mirrors 2, 3, and 4 SI IUUIU therefore be located far away from objective 6, measured along me umiudt ray CS, because they then do not need to be so large.
• all of the mirrors 2 - 4 has small sizes, because they are located relatively far away from objective 6, measured along the central ray CS. This possibility to minimize the sizes of the mirrors is a definite advantage compared to the first Porro system, where two of the four reflecting surfaces normally must be made relatively large.
• Requirement 6 above stipulated that the optical axis for ocular 5 should be located in or near plane SP. It turns out that even this requirement may be fulfilled with optics according to the invention.
• Mirror 3 throws in turn CS oblique forward-downward in the telescope, so that CS strikes mirror 4 at a location near or in plane SP. If CS strikes mirror 4 at a point lying in plane SP, the ocular optic axis should according to requirement 1 ) above also be located in plane SP, and therefore can the exterior of the telescope then with advantage be made wholly symmetrical. The angular position for mirror 4 must therefore be adjusted so that CS, after reflection in mirror 4, is parallel with in the instrument entering CS, and by that plane SP.
• Line RL (roofline) is an imaginary intersection line for the reflecting planes 2 and 3.
• Angle - is defined as the angle between line RL and plane SP.
• Imaginary axis AX is defined as the axis which intersects point P and forms the same angle to the reflecting plane 2, as to reflecting plane 3, and which is orthogonal to intersection line RL.
• the image tilt may be varied, and hence be adjusted down to zero, by adjustment of the angle o , which in practice preferably is done in such a way that the mirrors 2 and 3 as a unit are adjusted by small angular motions around the imaginary axis AX, until the right value for angle ⁇ • * . is reached.
• the light path be "mirrored", so that CS, seen from the ocular side of the telescope, is mirrored forward-upward by mirror 1 , thrown downward by mirror 2, and forward-upward by mirror 3.
• the angles /b and Y can of course be changed from their in figure 4 shown values, too.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Astronomy & Astrophysics (AREA)
• Telescopes (AREA)
• Optical Radar Systems And Details Thereof (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

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• 1989
  • 1989-08-22 SE SE8902786A patent/SE467941B/sv not_active IP Right Cessation
• 1990
  • 1990-08-21 WO PCT/SE1990/000540 patent/WO1991002995A1/en not_active Application Discontinuation
  • 1990-08-21 JP JP51219890A patent/JPH04507307A/ja active Pending
  • 1990-08-21 EP EP19900913183 patent/EP0489095A1/en not_active Withdrawn
  • 1990-08-21 AU AU62930/90A patent/AU6293090A/en not_active Abandoned

Non-Patent Citations (1)

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