Focusing system for optical instrument

Abstract

A focusing device includes a first tube, a second tube including an aperture defining surface shaped to define an aperture, where the first tube extends into the aperture, an optical element coupled to one of the first tube and the second tube for movement therewith, a plurality of rolling members coupled to the first tube and the second tube, at least one rolling member is disposed in each of the plurality of slots or grooves to contact the outer surface of the first tube and the aperture-defining surface of the second tube, wherein relative movement between the first tube and the second tube is facilitated by rolling movement of the rolling members in their respective slots or grooves in the longitudinal direction along the outer surface of the first tube and the bore-defining surface of the second tube.

Description

Focusing systems for optical instruments Technical Field

[0001] The present invention relates to the field of optical instruments, such as telescopes, etc. Some aspects of the present invention provide a focusing system for an optical instrument, such as a telescope, etc. Background Art

[0002] The focusing system of a telescope typically consists of two tubular sections of different diameters, arranged together (usually approximately coaxially), with light passing through the inner (smaller diameter) tube. One of the tubular sections is typically fixed to the main structure (base) of the telescope and is often called the fixed tube; the other tubular section can move along the common axial direction of the two tubular sections and is often called the moving tube.

[0003] The moving tube may include, support, and / or house a plurality of optical components, such as, for example, one or more lenses, one or more reflectors, etc. The moving tube may also include, support, and / or house optical devices, such as, for example, an image capture device, etc. As the moving tube moves, the position of the optical elements and / or optical devices in the optical path also changes, thereby achieving focus adjustment.

[0004] In some focusing systems, the diameter of the fixed tube may be smaller than the diameter of the moving tube, in which case the fixed tube may be referred to as the inner tube and the moving tube as the outer tube. In other focusing systems, the diameter of the fixed tube may be larger than the diameter of the moving tube, in which case the fixed tube may be referred to as the outer tube and the moving tube as the inner tube. In either case, a gap (e.g., a gap having a circumferential or annular cross-sectional shape between the outer circumferential surface of the inner tube and the inner circumferential surface of the outer tube) is typically present between the fixed tube and the moving tube to allow relative movement between the moving tube and the fixed tube.

[0005] FIG1 schematically illustrates a conventional prior art focusing system 10. The prior art focusing system 10 includes a moving tube 4 and a fixed tube 2. An optical element 6 can be coupled to the moving tube 4. Both the moving tube 4 and the fixed tube 2 extend in a longitudinal direction indicated by a double-headed arrow 9 and are generally coaxial along an axis 1 extending in the longitudinal direction 9.

[0006] In the illustrated embodiment of FIG1 , the movable tube 4 has a larger diameter than the fixed tube 2 and is therefore the outer tube 4. The movable tube 4 includes a hole-defining surface 8 that defines a hole 5, such that the fixed tube 2 extends through the hole 5 of the movable tube 4. When the fixed tube 2 extends into the hole 5 of the movable tube 4, a gap 7 having a generally annular cross-section (in a plane orthogonal to the longitudinal direction 9) is formed between the outer circumferential surface 3 of the inner tube 2 (in the focusing system 10 of the embodiment of FIG1 , the fixed tube 2) and the hole-defining surface 8 of the outer tube 4 (in the focusing system 10 of the embodiment of FIG1 , the movable tube 4). The gap 7 allows relative movement of the movable tube 4 and the fixed tube 2 in the longitudinal direction 9.

[0007] In operation, light enters the focusing system 10 along an optical axis 1. It is desirable that the optical axis 1 is substantially parallel to a longitudinal direction 9. The moving tube 4 is movable in the longitudinal direction 9 relative to the fixed tube 2. As the moving tube 4 moves, the optical element 6 coupled to the moving tube 4 can move in the longitudinal direction 9. Movement of the optical element 6 in the longitudinal direction 9 causes the optical element 6 to move to different longitudinal positions along the optical axis 1. Consequently, the focus and / or other optical properties of the optical element 6 may shift in the longitudinal direction 9, thereby allowing focus control. Various mechanisms for facilitating movement of the moving tube 4 in the longitudinal direction 9 relative to the fixed tube 2 are known in the art. Some known mechanisms are described below.

[0008] In some focusing systems, there may be surface contact between the fixed tube 2 and the moving tube 4 (e.g., between the bore-defining surface 8 of the outer tube 4 and the outer circumferential surface 3 of the inner tube 2). This surface contact may allow the fixed tube 2 to provide support for the moving tube 4. In some such focusing systems, the gap 7 between the fixed tube 2 and the moving tube 4 is filled with a lubricant to minimize friction associated with the surface contact between the two tubes 2, 4. The characteristics of the gap 7 between the fixed tube 2 and the moving tube 4 (e.g., size, shape, etc.), and any changes in these characteristics, may have a significant impact on the operation of the focusing system 10.

[0009] A large gap 7 generally facilitates smooth axial movement of the moving tube 4 relative to the fixed tube 2, but allows the moving tube 4 and any optical components 6 and / or optical devices to move radially (e.g., orthogonal to the longitudinal direction 9) relative to the fixed tube 2. Relative radial motion between the moving tube 4 and the fixed tube 2 can lead to a detrimental effect known as image drift.

[0010] A small gap 7 is beneficial for reducing the image drift of the focusing system 7, but it usually requires that the contact surfaces of the movable tube 4 and the fixed tube 2 (such as the hole-defining surface 8 of the outer tube 4 and the outer circumferential surface 3 of the inner tube 2) have higher processing accuracy and higher assembly accuracy, which correspondingly increases the manufacturing cost.

[0011] The small gap 7 between the moving tube 4 and the fixed tube 2 also makes the focusing system 10 more susceptible to mechanical failure, which can prevent the moving tube 4 from moving smoothly relative to the fixed tube 2. By way of non-limiting example, such mechanical failure may be caused by scratches on the contact surfaces, dust intrusion, a sharp increase in lubricant viscous damping at low temperatures, etc. In some cases, the moving tube 4 may become stuck due to such mechanical failure.

[0012] One conventional approach to addressing this problem is to use linear guides or bearings to achieve linear contact between the fixed and movable tubes. Preloading mechanisms can be used to eliminate backlash. However, this conventional solution is complex and expensive.

[0013] Figure 1A depicts a perspective view of a conventional prior art focusing system 10A having a rotary bearing 12A. Figure 1B depicts an enlarged fragmentary perspective view of Figure 1 A. In Figure 1A, focusing system 10A shows a preload mechanism 11A.

[0014] Focusing system 10A includes a moving (inner) tube 2A and a fixed (outer) tube 4A (shown transparently). The diameter of fixed tube 4A is larger than the diameter of moving tube 2A. A bearing 12A is positioned between an outer circumferential surface 3A of moving tube 2A and an inner (bore-defining) surface (not explicitly enumerated) of fixed tube 4A to facilitate movement of moving tube 2A relative to fixed tube 4A in a longitudinal direction 9A. A preload mechanism 11A (shown in FIG. 1B ) applies a radially oriented (relative to axis 1A) force between inner tube 2A and outer tube 4A, which tends to force outer surface 3A of inner tube 2A into engagement with bearing 12A and bearing 12A into engagement (contact) with the bore-defining surface of outer tube 4A.

[0015] The traditional focusing system 10A has the disadvantages of complex structure and high cost.

[0016] Therefore, there is still a need for a focusing system that is relatively low cost, simple, and at least improves image drift.

[0017] Summary of the Invention

[0018] The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools, and methods, which are intended to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments involve other improvements.

[0019] One aspect of the present invention provides a focusing device for an optical instrument such as a telescope. The focusing device includes a first tube extending in a longitudinal direction, a second tube extending in the longitudinal direction, the second tube including a hole-defining surface shaped to define a hole extending in the longitudinal direction, wherein the first tube extends to the hole, an optical element coupled to one of the first tube and the second tube for movement therewith, a spacer element positioned between an outer surface of the first tube and the hole-defining surface of the second tube, the spacer element shaped to define a plurality of slots therethrough, and a plurality of rolling members, at least one rolling member being disposed in each slot to contact the outer surface of the first tube and the hole-defining surface of the second tube, wherein the rolling members facilitate relative movement between the first tube and the second tube in the longitudinal direction by rolling in their respective slots along the outer surface of the first tube and the hole-defining surface of the second tube in the longitudinal direction.

[0020] The slots and rolling members may be shaped such that the slots constrain movement of the rolling members within their respective slots. The slots may extend in a longitudinal direction and the slots and rolling members may be shaped such that the slots guide rolling motion of the rolling members, which is generally confined to the longitudinal direction within their respective slots. The slots may be circular.

[0021] The plurality of slots may include at least a first pair of slots spaced apart from each other in a longitudinal direction and at least a second pair of slots spaced apart from each other in an angular direction about the longitudinally extending axis. At least one of the position and shape of the slots may be such that rolling movement of the rolling members in their respective slots along the longitudinal direction of the outer surface of the first tube and the bore-defining surface of the second tube maintains the first tube and the second tube in a substantially coaxial relationship, thereby mitigating image drift.

[0022] At least one of the position and shape of the slots can be such that rolling movement of the rolling members in their respective slots along the outer surface of the first tube and the bore-defining surface of the second tube in the longitudinal direction maintains the first and second tubes substantially coaxially along the longitudinally extending axis, thereby mitigating image drift. Contact between the rolling members and the outer surface of the first tube and contact between the rolling members and the bore-defining surface of the second tube can maintain a space between the outer surface of the first tube and the bore-defining surface of the second tube.

[0023] The space between the outer surface of the first tube and the hole-defining surface of the second tube may have an annular cross-sectional shape in a cross section perpendicular to the longitudinal direction. The rolling member may include a ball bearing. The rolling member may include a cylindrical roller (e.g., a wheel). The plurality of slots may include at least four slots. The plurality of slots may include 8 to 10 slots. At least some of the plurality of slots may be arranged to be collinear with each other in the longitudinal direction and spaced apart from each other. At least two groups of slots in the plurality of slots may be arranged to be collinear with each other in the longitudinal direction and spaced apart from each other.

[0024] At least some of the plurality of slots may be arranged to be located at the same position in the longitudinal direction and angularly spaced apart from each other about the longitudinally extending axis. At least two groups of slots in the plurality of slots may be arranged to be located at the same position in the longitudinal direction and angularly spaced apart from each other about the longitudinally extending axis. The liner element may be semi-tubular and may extend in the longitudinal direction, having a semi-circular cross-section in a plane orthogonal to the longitudinal direction, the semi-circular cross-section corresponding to an arc of less than 360°. The arc may be in the range of approximately 45°-180°. The arc may be in the range of approximately 75°-150°.

[0025] The focusing apparatus may include an orthogonal bias system operable to apply an orthogonal force to the second tube, the orthogonal force oriented to have a component orthogonal to the longitudinal direction, the orthogonal force maintaining contact between the rolling member and the outer surface of the first tube and contact between the rolling member and the aperture-defining surface of the second tube, and maintaining the first tube and the second tube in a substantially coaxial relationship, thereby mitigating image drift.

[0026] The focusing apparatus may include an orthogonal bias system operable to apply an orthogonal force to the first tube, the orthogonal force oriented to have a component orthogonal to the longitudinal direction, the orthogonal force maintaining contact between the rolling member and the outer surface of the first tube and contact between the rolling member and the aperture-defining surface of the second tube, and maintaining the first tube and the second tube in a substantially coaxial relationship, thereby mitigating image drift.

[0027] The orthogonal biasing system may include a biasing mechanism comprising a compression spring and a pressure plate, the pressure plate being directly or indirectly connected to a base of the focusing apparatus via another fixed component. The pressure plate may be adjustably connected to the base to control the amount of orthogonal force applied by the orthogonal biasing system.

[0028] The orthogonal bias system may further include a friction block coupled to one of the first tube and the second tube, the friction block including a friction surface, a focus adjustment shaft in contact with the friction surface and supported for rotation about a focus adjustment axis substantially orthogonal to the longitudinal direction, and a biasing mechanism for applying a second force that forces the focus adjustment shaft against the friction surface and thereby generates an orthogonal force.

[0029] The biasing system may include a biasing mechanism comprising a compression spring and a pressure plate, the pressure plate being directly or indirectly connected to a base of the focus arrangement via another fixed component. The pressure plate may be adjustably connected to the base to control the amount of normal force applied by the normal biasing system. The second force may be directed in a direction substantially orthogonal to both the longitudinal direction and the focus adjustment axis. The second force may be directed in a direction having a component orthogonal to both the longitudinal direction and the focus adjustment axis.

[0030] The focusing device may include an axis support block defining a recess, wherein the focus adjustment axis is supported by the axis support block within the recess. The focusing device may include one or more pivot joints, and wherein the focus adjustment axis is supported by the one or more pivot joints to rotate about the focus adjustment axis. The normal force may help promote the rolling movement of the rolling members in their respective slots along the outer surface of the first tube and the hole-defining surface of the second tube in the longitudinal direction. The normal force may help to reduce the sliding movement of the rolling members along the outer surface of the first tube and the hole-defining surface of the second tube. The focusing device may include a longitudinal force applying mechanism connected to provide a force that causes relative movement between the first tube and the second tube in the longitudinal direction. The longitudinal force applying mechanism may include a friction block, a focus adjustment axis and a biasing mechanism.

[0031] Another aspect of the present invention provides a focusing device for an optical instrument such as a telescope. The focusing device includes a first tube extending in a longitudinal direction, a second tube extending in the longitudinal direction, the second tube including a hole-defining surface shaped to define a hole extending in the longitudinal direction, wherein the first tube extends to the hole, an optical element coupled to one of the first tube and the second tube for movement therewith, an outer surface of the first tube or at least one of the hole-defining surfaces of the second tube shaped to define a plurality of grooves, and a plurality of rolling members, at least one rolling member being disposed in each groove to contact the outer surface of the first tube and the hole-defining surface of the second tube, wherein rolling movement of the rolling members in their respective grooves along the outer surface of the first tube and the hole-defining surface of the second tube in the longitudinal direction promotes relative movement between the first tube and the second tube in the longitudinal direction.

[0032] The outer surface of the first tube may be shaped to define a first plurality of grooves; the bore-defining surface of the second tube may be shaped to define a second plurality of grooves; at least one rolling member may be disposed in each groove of the first plurality of grooves and each groove of the second plurality of grooves. The grooves and rolling members may be shaped such that the grooves restrict movement of the rolling members within their respective grooves. The grooves may extend in a longitudinal direction, and the grooves and rolling members may be shaped such that the grooves guide rolling motion of the rolling members, with the rolling motion being substantially confined to the longitudinal direction within their respective grooves.

[0033] The plurality of grooves may include at least a first pair of grooves spaced apart from each other in the longitudinal direction and at least a second pair of grooves spaced apart from each other in an angular direction about the longitudinally extending axis. At least one of the position and shape of the grooves is such that rolling movement of the rolling members in their respective grooves along the outer surface of the first tube and the bore-defining surface of the second tube in the longitudinal direction maintains the first tube and the second tube in a substantially coaxial relationship, thereby mitigating image drift.

[0034] At least one of the position and shape of the grooves is such that rolling movement of the rolling members in their respective grooves along the outer surface of the first tube and the bore-defining surface of the second tube in the longitudinal direction maintains the first and second tubes in a substantially coaxial relationship along the longitudinally extending axis, thereby mitigating image drift. Contact between the rolling members and the outer surface of the first tube and contact between the rolling members and the bore-defining surface of the second tube can maintain a space between the outer surface of the first tube and the bore-defining surface of the second tube.

[0035] The space between the outer surface of the first tube and the hole-defining surface of the second tube may have an annular cross-sectional shape in a cross section perpendicular to the longitudinal direction. The rolling member may include a ball bearing. The rolling member may include a cylindrical roller (eg, a wheel).

[0036] The focusing apparatus may include an orthogonal biasing system operable to apply an orthogonal force to the second tube, the orthogonal force oriented to have a component orthogonal to the longitudinal direction, the orthogonal force maintaining contact between the rolling members and their respective grooves and maintaining the first tube and the second tube in a generally coaxial relationship, thereby mitigating image drift. The focusing apparatus may include an orthogonal biasing system operable to apply an orthogonal force to the first tube, the orthogonal force oriented to have a component orthogonal to the longitudinal direction, the orthogonal force maintaining contact between the rolling members and their respective grooves and maintaining the first tube and the second tube in a generally coaxial relationship, thereby mitigating image drift.

[0037] The orthogonal biasing system may include a biasing mechanism comprising a compression spring and a pressure plate, the pressure plate being directly or indirectly connected to a base of the focus assembly via another component. The pressure plate may be adjustably connected to the base to control the amount of orthogonal force applied by the orthogonal biasing system. The orthogonal biasing system may also include a friction block coupled to one of the first tube and the second tube, the friction block comprising a friction surface, the focus adjustment shaft contacting the friction surface and supported for rotation about a focus adjustment axis generally perpendicular to the longitudinal direction, the biasing mechanism being configured to apply a second force that urges the focus adjustment shaft against the friction surface and thereby generates the orthogonal force.

[0038] The biasing system can include a biasing mechanism comprising a compression spring and a pressure plate, the pressure plate being directly or indirectly connected to a base of the focusing device via another component. The pressure plate can be adjustably connected to the base to control the amount of normal force applied by the normal biasing system. The normal force can help maintain contact between the rolling members and the outer surface of the first tube and the aperture-defining surface of the second tube. The normal force can help promote rolling motion of the rolling members in their respective grooves in a longitudinal direction. The force can help mitigate sliding motion of the rolling members in their respective grooves.

[0039] Another aspect of the present invention provides a focusing device for an optical instrument such as a telescope. The focusing device includes a first tube extending in a longitudinal direction, a second tube extending in the longitudinal direction, the second tube including a hole-defining surface shaped to define a hole extending in the longitudinal direction, wherein the first tube extends to the hole, an optical element coupled to one of the first tube and the second tube for movement therewith, a spacer element positioned between an outer surface of the first tube and the hole-defining surface of the second tube, the spacer element shaped to define a plurality of grooves on its surface, and a plurality of rolling members, at least one rolling member being disposed in each groove to contact the spacer element surface and one of the outer surface of the first tube and the hole-defining surface of the second tube, wherein relative movement between the first tube and the second tube in the longitudinal direction is facilitated by rolling movement of the rolling members in their respective grooves along the spacer element surface and one of the outer surface of the first tube and the hole-defining surface of the second tube in the longitudinal direction.

[0040] One of the outer surface of the first tube and the bore-defining surface of the second tube may be shaped to define a second plurality of grooves; at least one rolling member may be disposed in each of the plurality of grooves and each of the second plurality of grooves. The grooves and rolling members may be shaped such that the grooves constrain movement of the rolling members within their respective grooves. The grooves may extend in a longitudinal direction, and the grooves and rolling members may be shaped such that the grooves guide rolling motion of the rolling members, the rolling motion being substantially confined to the longitudinal direction within their respective grooves.

[0041] The plurality of grooves may include at least a first pair of grooves spaced apart from each other in the longitudinal direction and at least a second pair of grooves spaced apart from each other in an angular direction about the longitudinally extending axis. At least one of the position and shape of the grooves may be such that rolling motion of the rolling members in their respective grooves along the outer surface of the first tube and the bore-defining surface of the second tube in the longitudinal direction maintains the first tube and the second tube in a substantially coaxial relationship, thereby mitigating image drift.

[0042] At least one of the position and shape of the grooves can be such that rolling movement of the rolling members in their respective grooves along one of the outer surface of the first tube and the bore-defining surface of the second tube in a longitudinal direction maintains the first and second tubes in a substantially coaxial relationship along the longitudinally extending axis, thereby mitigating image drift. Contact between the rolling members and the backing element surface and between the rolling members and one of the outer surface of the first tube and the bore-defining surface of the second tube can maintain a space between the outer surface of the first tube and the bore-defining surface of the second tube.

[0043] The space between the outer surface of the first tube and the hole-defining surface of the second tube can have an annular cross-sectional shape in a cross section perpendicular to the longitudinal direction. The rolling member can include a ball bearing. The rolling member can include a cylindrical roller (e.g., a wheel). The liner element can be semi-tubular and extend in the longitudinal direction, having a semi-annular cross-section in a plane perpendicular to the longitudinal direction, the arc corresponding to the semi-annular cross-section being less than 360°.

[0044] The focusing apparatus may include an orthogonal biasing system operable to apply an orthogonal force to the second tube, the orthogonal force oriented to have a component orthogonal to the longitudinal direction, the orthogonal force maintaining contact between the rolling members and their respective grooves and maintaining the first tube and the second tube in a generally coaxial relationship, thereby mitigating image drift. The focusing apparatus may include an orthogonal biasing system operable to apply an orthogonal force to the first tube, the orthogonal force oriented to have a component orthogonal to the longitudinal direction, the orthogonal force maintaining contact between the rolling members and their respective grooves and maintaining the first tube and the second tube in a generally coaxial relationship, thereby mitigating image drift.

[0045] The orthogonal biasing system may include a biasing mechanism comprising a compression spring and a pressure plate, the pressure plate being directly or indirectly connected to a base of the focus assembly via another component. The pressure plate may be adjustably connected to the base to control the amount of orthogonal force applied by the orthogonal biasing system. The orthogonal biasing system may also include a friction block coupled to one of the first tube and the second tube, the friction block comprising a friction surface, the focus adjustment shaft contacting the friction surface and supported for rotation about a focus adjustment axis generally perpendicular to the longitudinal direction, the biasing mechanism being configured to apply a second force that urges the focus adjustment shaft against the friction surface and thereby generates the orthogonal force.

[0046] The biasing system can include a biasing mechanism comprising a compression spring and a pressure plate, the pressure plate being directly or indirectly connected to a base of the focusing device via another component. The pressure plate can be adjustably connected to the base to control the amount of normal force applied by the normal biasing system. The normal force can help maintain contact between the rolling members and the outer surface of the first tube and the aperture-defining surface of the second tube. The normal force can help promote rolling motion of the rolling members in their respective grooves in a longitudinal direction. The normal force can help mitigate sliding motion of the rolling members in their respective grooves.

[0047] Another aspect of the present invention provides a method for focusing an optical instrument, such as a telescope, comprising providing a first tube extending in a longitudinal direction, providing a second tube extending in the longitudinal direction, the second tube including a bore-defining surface shaped to define a bore extending in the longitudinal direction, wherein the first tube extends into the bore, providing an optical element coupled to one of the first tube and the second tube for movement therewith, providing a spacer element positioned between an outer surface of the first tube and the bore-defining surface of the second tube, the spacer element shaped to define a plurality of slots extending therethrough, providing a plurality of rolling members, at least one rolling member disposed in each slot to contact the outer surface of the first tube and the bore-defining surface of the second tube, wherein relative movement between the first tube and the second tube in the longitudinal direction is facilitated by rolling movement of the rolling members in their respective slots along the outer surface of the first tube and the bore-defining surface of the second tube in the longitudinal direction.

[0048] Another aspect of the present invention provides a method for focusing an optical instrument, such as a telescope. The method includes providing a first tube extending in a longitudinal direction, providing a second tube extending in the longitudinal direction, the second tube including a bore-defining surface shaped to define a bore extending in the longitudinal direction, wherein the first tube extends into the bore, providing an optical element coupled to one of the first tube and the second tube for movement therewith, providing at least one of an outer surface of the first tube and the bore-defining surface of the second tube shaped to define a plurality of grooves, and providing a plurality of rolling members, at least one rolling member disposed in each groove to contact the outer surface of the first tube and the bore-defining surface of the second tube to facilitate relative movement between the first tube and the second tube by rolling movement of the rolling members in their respective grooves along the outer surface of the first tube and the bore-defining surface of the second tube in the longitudinal direction.

[0049] Yet another aspect of the present invention provides a method for focusing an optical instrument, such as a telescope, comprising providing a first tube extending in a longitudinal direction, providing a second tube extending in the longitudinal direction, the second tube including a bore-defining surface shaped to define a bore extending in the longitudinal direction, wherein the first tube extends into the bore, providing an optical element coupled to one of the first tube and the second tube for movement therewith, providing a spacer element positioned between an outer surface of the first tube and the bore-defining surface of the second tube, the spacer element shaped to define a plurality of grooves in its surface, providing a plurality of rolling members, at least one rolling member disposed in each groove to contact the spacer element surface and one of the outer surface of the first tube and the bore-defining surface of the second tube, and promoting relative movement between the first tube and the second tube in the longitudinal direction by rolling movement of the rolling members in their respective grooves along the spacer element surface and one of the outer surface of the first tube and the bore-defining surface of the second tube in the longitudinal direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Other features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0051] FIG1 schematically illustrates a conventional prior art focusing system.

[0052] FIG. 1A depicts a perspective view of a conventional prior art focusing system.

[0053] FIG. 1B depicts an enlarged perspective view of a portion of the conventional prior art focusing system of FIG. 1A .

[0054] FIG2 schematically illustrates a cross-sectional view of an optical instrument according to an example embodiment.

[0055] FIG3 schematically illustrates a cross-sectional view of a focusing system according to an example embodiment.

[0056] FIG4 is an exploded perspective view of a moving tube and a fixed tube of the focusing system of FIG3.

[0057] FIG. 5A schematically shows a perspective assembly diagram of the movable tube and the fixed tube shown in FIG. 4 .

[0058] FIG. 5B schematically shows another perspective assembly view of the movable tube and the fixed tube shown in FIG. 4 .

[0059] 6 schematically illustrates a partial cross-sectional view of the focusing system of FIG. 3 taken along line 6 - 6 shown in FIG. 5B , according to one embodiment.

[0060] 7 schematically illustrates a partial cross-sectional view of the focusing system of FIG. 3 taken along line 7 - 7 shown in FIG. 3 , according to one embodiment.

[0061] FIG. 8A illustrates a perspective view of a cushioning element according to an example embodiment.

[0062] 8B illustrates a cross-sectional view of another example focusing system including the spacer element shown in FIG. 8A.

[0063] 9A and 9B schematically illustrate perspective views of other cushioning elements according to other example embodiments.

[0064] FIG. 9C schematically illustrates a perspective view of a fixation tube according to an example embodiment.

[0065] FIG9D schematically illustrates a perspective view of a moving tube according to example embodiments.

[0066] It should be noted that throughout the drawings, like features are identified by like reference numerals. DETAILED DESCRIPTION

[0067] A focusing device for an optical instrument such as a telescope is disclosed. The focusing device includes: a first tube extending in a longitudinal direction; and a second tube extending in the longitudinal direction. The second tube includes a hole-defining surface that is shaped to define a hole extending in the longitudinal direction. The first tube extends into the hole. An optical element is coupled to one of the first tube and the second tube to move therewith. A padding element is located between the outer surface of the first tube and the hole-defining surface of the second tube and is shaped to define a plurality of slots passing through the padding element. The focusing device includes a plurality of rolling members, at least one rolling member being provided in each slot to contact the outer surface of the first tube and the hole-defining surface of the second tube. The rolling movement of the rolling members in their respective grooves along the outer surface of the first tube and the hole-defining surface of the second tube in the longitudinal direction promotes relative movement between the first tube and the second tube in the longitudinal direction.

[0068] Fig. 2 schematically illustrates an optical instrument (a telescope in the illustrated embodiment) 100 according to an exemplary embodiment of the invention. The telescope 100 comprises a focusing system 200 according to an exemplary embodiment of the invention.

[0069] Focusing system 200 includes a base 102. In some embodiments, base 102 includes a short tube 102A for holding an eyepiece or diagonal lens. Focusing system 200 includes a fixed tube 108 coupled to and supported by base 102, and a moving tube 106 movably coupled to fixed tube 108 for relative movement therebetween. Both moving tube 106 and fixed tube 108 are tubular and extend in a longitudinal direction (indicated by a double-headed arrow) 109. Moving tube 106 can move relative to fixed tube 108 in the longitudinal direction 109. Due to features of the focusing system 200 (described in greater detail below), this relative movement between the moving tube 106 and the fixed tube 108 along the longitudinal direction 109 is advantageous while maintaining an orientation between the moving tube 106 and the fixed tube 108 that is more coaxial than in prior art focusing systems—that is, the moving tube 106 and the fixed tube 108 are relatively closer to being coaxial (along the axis 101) during this relative movement between the moving tube 106 and the fixed tube 108 in the longitudinal direction 109 than in prior art focusing systems. It will be appreciated that deviations from this coaxial relative orientation are associated with image drift. Therefore, by maintaining an orientation between the moving tube 106 and the fixed tube 108 that is relatively more coaxial than in prior art focusing systems, the focusing system 200 mitigates image drift relative to prior art focusing systems.

[0070] In the embodiment of FIG2 , the diameter of mobile tube 106 is larger than the diameter of fixed tube 108. Therefore, mobile tube 106 includes a hole 113. Fixed tube 108 can extend into hole 113 of mobile tube 106. A gap 113A can be formed between the outer circumferential surface of fixed tube 108 and the inner hole-defining surface of mobile tube 106. In other embodiments, the diameter of mobile tube 106 can be smaller than the diameter of fixed tube 108, so that mobile tube 106 extends into the hole of fixed tube 108.

[0071] An optical element (a mirror in the embodiment shown in FIG. 2 ) 104 is rigidly coupled to and supported by the moving tube 106. In the embodiment shown in FIG. 2 , the optical element 104 includes a hole, and the moving tube 106 extends into the hole of the optical element 104 and rests on a hole-defining surface 115 of the optical element 104, thereby supporting the optical element 104. In other embodiments, the optical element 104 may additionally or alternatively be mounted to and / or supported by the moving tube 106 using any suitable technique. When the position of the moving tube 106 is adjusted along the longitudinal direction 109 (relative to the fixed tube 108), the position of the optical element 104 moves with the moving tube 106, thereby achieving focus adjustment.

[0072] In operation, light enters telescope 100 through lens 103 and travels along one of longitudinal directions 109 toward focusing system 200. As the position of optical element 104 moves along axis 101, the longitudinal position at which the light strikes optical element 104 also moves. The focus of telescope 100 changes accordingly.

[0073] FIG3 schematically illustrates a detailed view of the focusing system 200 of FIG2 , according to an example embodiment.

[0074] 3 , the focus system 200 includes a friction block 110 coupled to the moving tube 106 and a focus adjustment shaft 112 adjacent to and in contact with a friction surface 111 of the friction block 110 at a contact point 111A. The focus adjustment shaft 112 can be rotated by a user or by a motor of an autofocus system about its axis 112A (extending into and out of the page in the view of FIG. 3 and generally orthogonal to the longitudinal direction 109) to adjust the focus of the focus system 200 by moving the moving tube 106 relative to the fixed tube 108 in the longitudinal direction 109.

[0075] When the focus adjustment shaft 112 rotates, a friction force oriented in one of the longitudinal directions 109 is generated on the friction surface 111. Clockwise rotation of the focus adjustment shaft 112 generates a friction force in a first longitudinal direction 109. Counterclockwise rotation of the focus adjustment shaft 112 generates a friction force in a second longitudinal direction 109 opposite the first longitudinal direction.

[0076] The focusing system 200 also includes a shaft support block 114, which includes a recess 114A (in the illustrated embodiment, the recess has a V-shaped cross-section (in a plane including the axis 101) with generally flat side walls) that is shaped to support the focus adjustment shaft 112 and maintain the focus adjustment shaft 112 in an appropriate position in the recess 114A while allowing the focus adjustment shaft 112 to rotate about its axis 112A.

[0077] In other embodiments, the recess 114A of the shaft support block 114 may have other shapes (e.g., other cross-sectional shapes in a plane including the axis 101) to support the focus adjustment shaft 112 in position in the recess 114A while allowing such rotational movement of the focus adjustment shaft 112. In other embodiments, the shaft support block 114 may include other mechanisms for supporting the focus adjustment shaft 112 in position while allowing such rotational movement of the focus adjustment shaft 112.

[0078] The focusing system 200 also includes a biasing mechanism or force applicator 116 that forces the focus adjustment shaft 112 against the friction surface 111 (see force arrow 132a in FIG6 ) and, due to the contact between the friction block 110 and the moving tube 106 , in turn applies a force to the moving tube 106 (see force arrow 132b ). These forces are oriented in directions that are generally orthogonal to the longitudinal direction 109 or have a directional component orthogonal to the longitudinal direction 109 (and the axis 101 ). Such forces 132a, 132b (and force 132c, explained in more detail below) may be referred to herein as orthogonal forces 132a, 132b, 132c (or collectively, orthogonal forces 132 ) because they are oriented with a directional component orthogonal to the longitudinal direction 109 (and the axis 101 ). In the illustrated embodiment, the biasing mechanism 116 includes a spring 116A and a pressure plate 118 . In the embodiment of FIG3 , the spring 116A is located between the pressure plate 118 and the shaft support block 114 . The pressure plate 118 is adjustably mounted (e.g., threadedly) to the base 102 so that the adjustable position of the pressure plate 118 adjustably compresses the spring 116A, which in turn applies a normal force to the shaft support block 114 and forces the focus adjustment shaft 112 against the friction surface 111 (due to the contact between the friction block 110 and the moving tube 106), thereby applying a normal force 132a to the moving tube 106. The direction in which the biasing mechanism 116 forces the focus adjustment shaft 112 against the friction surface 111 (normal force 132a) and applies a force to the moving tube 106 (normal force 132b)) can be roughly orthogonal to the longitudinal direction 109 and the axis 101 and the rotation axis 112A of the focus adjustment shaft 112 (or has a component orthogonal to the longitudinal direction 109 and the axis 101 and the rotation axis 112A of the focus adjustment shaft 112), and can be roughly perpendicular to the friction surface 111, although such orthogonal force 132 can have a small non-orthogonal component.

[0079] When the focus adjustment shaft 112 rotates about its axis 112A, a friction force oriented along one of the longitudinal directions 109 is generated on the friction surface 111. This friction force, in turn, causes the friction block 110 to displace relative to the focus adjustment shaft 112 in the corresponding one of the longitudinal directions 109. The focus adjustment shaft 112 is held within the recess 114A by the shaft support block 114. Because the friction block 110 is rigidly coupled to the moving tube 106 and the optical element 104 is rigidly coupled to the moving tube 106, the movement of the friction block 110 causes corresponding movement of the moving tube 106 and the optical element 104 in the corresponding longitudinal direction 109.

[0080] The fixed tube 108 is rigidly fixed to the base 102. Thus, as the moving tube 106 moves along one of the longitudinal directions 109, the moving tube 106 moves relative to the fixed tube 108. In the illustrated example embodiment of the focusing system 200, the moving tube 106 can move in the longitudinal direction 109, with a range of motion between the bottom wall 102B of the base 102 and the connection end 105A of the light shielding tube 105. As described below, to ensure smooth and stable relative movement between the moving tube 106 and the fixed tube 108, the focusing system 200 may further include a suitable mechanism between the moving tube 106 and the fixed tube 108 to facilitate relative movement.

[0081] Fig. 4 schematically shows an exploded view of the focusing system 200 of Fig. 3. The illustration of Fig. 4 omits some components of the focusing system 200 to more clearly illustrate certain features of the focusing system 200.

[0082] The focusing system 200 includes a spacer element 120. In the embodiment of FIG4 , the spacer element 120 is semi-tubular (i.e., having a semi-circular cross-section in a plane normal to the axis 101, corresponding to an arc of less than 360° (in some embodiments, in the range of 45°-180° about the axis 101, and in some embodiments, in the range of 75°-150° about the axis 101) and is sized to be positioned in the gap 113A between the moving tube 106 and the fixed tube 108. The spacer element 120 includes a first (e.g., concave) surface 120a, which, in the illustrated embodiment, is disposed adjacent to the fixed (inner) tube 108, and an opposing second (e.g., convex) surface 120b, which, in the illustrated embodiment, is disposed adjacent to the moving (outer) tube 106.

[0083] The cushioning element 120 includes a first longitudinally extending edge 120c and a second longitudinally extending edge 120d, with a first surface 120a and a second surface 120b extending between the first edge 120c and the second edge 120d. The first (e.g., concave) surface 120a and the second (e.g., convex) surface 120b can be shaped to conform to (e.g., complement) the shape of the outer (convex and / or circumferential) surface 108A of the fixed tube 108 and the inner (convex, bore-defining) surface 108A of the mobile tube 106, respectively. For example, as described above, the first (e.g., concave) surface 120a and the second (e.g., convex) surface 120b can have an arcuate shape in a cross-section taken in a plane orthogonal to the axis 101.

[0084] The backing element 120 is shaped to define slots 122a-d (collectively, slots 122) extending in the longitudinal direction 109. In the embodiment of the focusing system 200 of FIG4 , the longitudinally extending slots 122 pass through the backing element 120 (from surface 120a to surface 120b). However, this is not required. The slots 122 may also be formed on the first surface 120a or the second surface 120b of the backing element 120. In other embodiments, the slots 122 may be formed on both the first surface 120a and the second surface 120b of the backing element 120.

[0085] The rolling members 124 can be located in the longitudinally extending slots 122. For example, the rolling members 124 can include ball bearings. In some embodiments, one rolling member 124 is placed in each slot 122.

[0086] The longitudinally extending slot 122 may have any suitable shape to allow the rolling member 124 to roll within the slot 122 along the longitudinal direction 109 .

[0087] The width of the slots 122 (in a direction transverse to their longitudinal extension) is sized to limit movement of the rolling member 124 in such a transverse direction. In some embodiments, the width of the slots 122 (in a direction transverse to their longitudinal extension) is sized such that there is substantially no room for lateral movement of the rolling member 124 along the width of the slots 122.

[0088] In some embodiments, the slots 122 can be arranged on the backing member 120 in certain geometric relationships. For example, in the embodiment shown in FIG4 , the focusing system 300 includes two pairs of slots ( 122a and 122b ; and 122c and 122d ), respectively, that are collinear with each other in the longitudinal direction 109. In the embodiment of FIG4 , the longitudinal distance between slots 122a and 122b is approximately the same as the distance between slots 122c and 122d. Slot 122a is located at a longitudinal position similar to slot 122c, and slot 122b is located at a longitudinal position similar to slot 122d. Other configurations of the slots 122 on the backing member 120 are possible and are described below.

[0089] The cushioning element 120 can be rigidly coupled to the mobile tube 106 or the stationary tube 108. As shown in FIG4 , the cushioning element 120 is shaped to define an opening 123 for coupling to the mobile tube 106. For example, to couple the cushioning element 120 to the mobile tube 106, the opening 123 of the cushioning element 120 is aligned with a corresponding fastening receptacle 125 of the mobile tube 106. A fastening device (e.g., a screw, rivet, etc., not shown in FIG4 ) can then be driven through the opening 123 and into the fastening receptacle 125 to securely fasten the cushioning element 120 to the mobile tube 106.

[0090] FIG5A and FIG5B (collectively, FIG5 ) schematically depict, in perspective view, an assembled view of a focusing system 200 according to an embodiment. Some portions of the focusing system 200 shown in FIG5 are shown in perspective and drawn with hidden (dashed) lines to more clearly show other features drawn with solid lines. Some portions of the focusing system 200 are not explicitly shown in FIG5 to make other portions of the focusing system 200 more visible. FIG6 is a schematic cross-sectional view of the focusing system 200 taken along section line 6-6 shown in FIG5B . FIG7 is a cross-sectional view of the focusing system 200 taken along section line 7-7 shown in FIG3 .

[0091] As shown in FIG5 , the movable tube 106 includes a hole-defining surface 106A shaped to provide a hole 113 through which the fixed tube 108 extends. An end 127 of the fixed tube 108 is fixed to the base 102 (e.g., fixedly coupled to or integrally formed with the base 102) (not shown in FIG5 ). A gasket 120 is positioned between the movable tube 106 and the fixed tube 108. As described above, the gasket 120 can be securely coupled to the movable tube 106. A rolling member 124 positioned within the slot 122 of the gasket 120 facilitates relative movement between the movable tube 106 and the fixed tube 108 in the longitudinal direction 109. Specifically, the rolling member 124 is supported on the outer (circumferential) surface 108A of the fixed (inner) tube 108 and the hole-defining surface 106A of the movable (outer) tube 106, and rolls along the slot between these two surfaces as the movable tube 106 moves relative to the fixed tube 108 in the longitudinal direction 109. The slot 122 may guide the rolling member 124 to roll in the longitudinal direction 109 and may limit movement of the rolling member 124 in other directions.

[0092] The friction block 110 is coupled to the moving tube 106 , and the focus adjustment shaft 112 is adjacent to and in contact with a friction surface 111 of the friction block 110 at a contact point 111A.

[0093] As described above, the focus adjustment shaft 112 can be rotated about its axis 112A by a user or by a motor of an autofocus system to adjust the focus of the focus system 200 by moving the moving tube 106 relative to the fixed tube 108 in the longitudinal direction 109. When the focus adjustment shaft 112 rotates, a friction force oriented along one of the longitudinal directions 109 is generated on the friction surface 111.

[0094] FIG6 is a schematic cross-sectional view of focusing system 200 taken along section line 6-6 shown in FIG5B. Referring to FIG6, focusing system 200 is symmetrical about a midplane 128 that divides focusing system 200 into a left half and a right half. Both friction block 110 and focus adjustment shaft 112 are symmetrical about midplane 128. Similarly, movable tube 106, fixed tube 108, and pad element 120 are also symmetrical about midplane 128. Midplane 128 of symmetry is preferably aligned with the direction of gravity, although this is not required.

[0095] 6 , due to the presence of rolling members 124, a gap space 130 exists between the pad element 120 and the fixed tube 108. Gap space 130 ensures that only the rolling members 124 are in physical contact with the fixed tube 108. Due to the presence of pad 120 and rolling members 124, a gap 113A exists between the mobile tube 106 and the fixed tube 108.

[0096] As described above, normal forces 132a are applied to the focus adjustment shaft 112 by the biasing mechanism 116 (not shown in FIG6 ), which in turn (through its contact with the friction block 110 and the contact of the friction block 110 with the moving tube 106) applies normal forces 132b to the moving tube 106. As also described above, these normal forces 132 can be directed orthogonal to the longitudinal direction 109 and the axis 101, or at least have components orthogonal to the longitudinal direction 109 and the axis 101, and tend to urge the moving tube 106 toward the fixed tube 108. Thus, the combination of the biasing mechanism 116, the shaft support block 114, the focus adjustment shaft 112, and the friction block 110 can be considered an orthogonal biasing system 121 (see FIG3 ) that urges the moving tube 106 toward the outer (circumferential) surface 108A of the fixed tube 108 (see normal force arrows 132c in FIG6 ). In this manner, the orthogonal force 132a applied by the orthogonal biasing system 121 applies a corresponding orthogonal force 132b on the moving tube 106, which applies a corresponding orthogonal force 132c to maintain contact between the bore-defining surface 106A of the moving tube 106 and the rolling member 124, and thereby maintain contact between the rolling member 124 and the outer (circumferential) surface 108A of the fixed tube 108. By applying these orthogonal forces 132, the orthogonal biasing system 121 maintains contact between the bore-defining surface 106A of the moving tube 106 and the rolling member 124, and thereby maintains contact between the rolling member 124 and the outer (circumferential) surface 108A of the fixed tube 108, which in turn minimizes play (e.g., radially relative to the axis 101) between the tubes 106, 108.

[0097] Advantageously (as discussed in more detail below), the orthogonal biasing system 121 allows longitudinal movement of the moving tube 106 relative to the fixed tube 108 while maintaining these orthogonal forces 132. In the illustrated embodiment, the orthogonal biasing system 121 allows movement due to a rolling relationship between the focus adjustment shaft 112 and the friction block 110 (as described in more detail below), but in other embodiments, this longitudinal movement between the tubes 106, 108 can be achieved using a suitable low-friction contact (e.g., sliding). In some embodiments, particularly where other components are used to implement the longitudinal force applying mechanism 119 (discussed in more detail below), the orthogonal biasing system 121 can be implemented using other suitable additional or alternative components that apply orthogonal forces 132b to the moving tube 106, and normal forces 132c that maintain contact between the bore-defining surface 106A of the moving tube 106 and the rolling member 124, and thus between the rolling member 124 and the outer (circumferential) surface 108A of the fixed tube 108.

[0098] The focusing apparatus 200 includes a longitudinal force applying mechanism 119 that allows focus adjustment by providing a longitudinally directed force that causes the moving tube 106 (and correspondingly the optical element 104) to move relative to the fixed tube in a longitudinal direction 109 (axial direction 101). Advantageously, in the particular case of the illustrated embodiment, the biasing mechanism 116 (spring 116A and pressure plate 118) provides the force used by both the longitudinal force applying mechanism 119 and the orthogonal biasing system 121 (although this is not required). More specifically, both the longitudinal force applying mechanism 119 and the orthogonal biasing system 121 derive their force from the biasing system 116 and both include the biasing mechanism 116, the focus adjustment shaft 112, and the friction block 110. The operation of the longitudinal force applying mechanism 119 will now be described in more detail.

[0099] The longitudinal force applying mechanism 119 of the illustrated embodiment includes the biasing mechanism 116, the focus adjustment shaft 112, and the friction block 110. As described above, the normal force 132a applied by the biasing mechanism 116 to the focus adjustment shaft 112 and, through the focus adjustment shaft 112, to the friction block 110 includes a force component oriented perpendicular to the friction surface 111 of the friction block 110. When the focus adjustment shaft rotates about its axis 112A, the normal force 132a causes friction (i.e., rolling friction) to exist between the friction surface 111 and the focus adjustment shaft 112.

[0100] 5, 6, and 7, a rotational torque about a rotational axis 112A can be applied to the focus adjustment shaft 112 by a user or by a motor of an autofocus system. The rotational torque generated by the user or the autofocus system on the focus adjustment shaft 112 generates a longitudinally oriented force (in one of the longitudinal directions 109) through rolling friction between the focus adjustment shaft 112 and the friction surface 111 of the friction block 110.

[0101] In some embodiments, the surface of the recess 114A of the shaft support block 114 includes a low-friction surface to facilitate sliding motion of the focus adjustment shaft 112 as it rotates about its axis 112A. In other embodiments, the focus system 200 includes one or more pivot joint mechanisms (not visible in the illustrated cross-sectional view) that facilitate rotation of the focus adjustment shaft 112 within the shaft support block 114. Such pivot joint mechanisms can maintain the focus adjustment shaft 112 spaced apart from the surface of the shaft support block 114 (except at the location of the pivot joint). Such pivot joint mechanisms can include a pair of pivot joint mechanisms spaced apart from each other in the direction of the axis 112A.

[0102] The friction block 110 can be rigidly coupled to the mobile tube 106 or integrally formed with the mobile tube 106 such that a longitudinal force on the friction block 110 (caused by rotation of the adjustment shaft 112) generates a corresponding longitudinal force on the mobile tube 106. Due to the longitudinal force on the mobile tube 106, the mobile tube 106 moves in the longitudinal direction 109 relative to the fixed tube 108.

[0103] The longitudinal force applying mechanism 119 of the illustrated embodiment is a non-limiting example of a mechanism for applying a force that causes relative longitudinal movement between the tubes 106 and 108. In other embodiments, such a longitudinal force may be provided by any of a variety of other systems. As a non-limiting example, the focus adjustment shaft 112 may be provided with a gear that is rotatable relative to a rack located on the outer surface of the moving tube 106 to allow the longitudinally directed force to be transmitted to the moving tube 106.

[0104] When a longitudinally directed force is applied to the mobile tube 106 by the longitudinal force applying mechanism 119, relative movement between the mobile tube 106 and the fixed tube 108 is facilitated by the rolling member 124 (within the narrow groove 122) rolling against the outer (circumferential) surface 108A of the fixed tube 108 and the hole defining surface 106A of the mobile tube 106.

[0105] In the embodiment shown in FIG6 , a normal force 132c acts on rolling member 124, forcing rolling member 124 against outer surface 108A of stationary tube 108 and aperture-defining surface 106A of mobile tube 106, thereby facilitating rolling member 124 rolling against both surfaces. In some embodiments, the component of normal force 132c aligned with force 132a can be generated in part by force 132a. In a currently preferred embodiment, the forces between tubes 106, 108 and rolling member 124, as well as the surface characteristics of rolling member 124 and surfaces 106A, 108A, cause rolling member 124 to roll relative to surfaces 106A, 108A without sliding, although this is not required. In some embodiments, in addition to or as an alternative to rolling, rolling member 124 can slide relative to one or both of surfaces 106A, 108A. In some embodiments, when the rolling member 124 rolls or otherwise moves within the slot 122 , the rolling member 124 moves longitudinally along the slot 122 and is guided to move longitudinally by the slot 122 .

[0106] The mechanism for enabling longitudinal movement between the moving tube 106 and the fixed tube 108 in the focus system 200 (e.g., the slotted pad 120 and the rolling member 124) allows the moving tube 106 and the fixed tube to maintain a coaxial orientation (at axis 101) relative to each other even with repeated relative longitudinal movement, thereby ameliorating image drift present in many prior art focus system designs. As described above, the slotted pad 120 and the rolling member 124 can be aided by the orthogonal biasing system 121, which forces the tubes 106, 108 into contact with the rolling member 124. Furthermore, the mechanism for enabling longitudinal movement between the moving tube 106 and the fixed tube 108 in the focus system 200 (e.g., the slotted pad 120, the rolling member 124, and the orthogonal biasing system 121) provides an inexpensive system for mitigating image drift and is less likely to tighten or damage itself with repeated use.

[0107] Referring now to FIG. 7 , focus system 200 includes a knob 134 coupled to focus adjustment shaft 112 on each side thereof such that knob 134 is substantially coaxial with focus adjustment shaft 112 about axis 112A. Knob 134 is rotatable about axis 112A. When knob 134 rotates about axis 112A, focus adjustment shaft 112 also rotates about axis 112A due to its fixed coupling with knob 134. Knob 134 can be used, for example, for manual focus adjustment.

[0108] Other configurations of spacer elements 120 and slots 122 are possible.

[0109] Figure 8A is a perspective view of a spacer element 820A according to another example embodiment. Figure 8B is a cross-sectional view of a spacer element 820A in a focusing system 800B according to an example embodiment.

[0110] 8A is formed with a plurality (eg, four) slots 822A-D defined therein. The slots 822A-D may be shaped (eg, longitudinally extending) substantially similar to the slots 122a-d described above.

[0111] For the cushion element 820A, a pair of slots 822A and 822B are non-collinear (e.g., the slots 822A, 822B are angularly offset from each other about the longitudinally extending axis 801). As shown in FIG. 8B , the slot 822A forms an angle 803 with the median plane 128. The slot 822B forms an angle 805 with the median plane 128 such that the angle 805 is greater than the angle 803. In the embodiment shown in FIG. 8A , because the angle 805 is greater than the angle 803, the slot 822B is closer to the edge 821A of the cushion element 820A than the slot 822A. However, this is not necessary. Required. In other embodiments, slot 822A can be more angularly offset (from midplane 128) than slot 822B, and thus closer to edge 821A than slot 822B. Similarly, slots 822C and 822D are angularly offset from each other about longitudinally extending axis 801. As shown in FIG8B , slot 822C forms an angle 807 with midplane 128. Slot 822D forms an angle 809 with midplane 128, such that angle 809 is greater than angle 807. In other words, liner 820A includes two pairs of non-collinear slots, namely, pair 822A-B and pair 822C-D.

[0112] In some embodiments, the longitudinal distance 823A between slot 822A and slot 822B can be different than the distance 823B between slot 822C and slot 822D.

[0113] As best shown in FIG8B , arc 825A represents the arc length between slots 822B and 822A. In some embodiments, the arc corresponding to arc 825A is less than 30 degrees. Arc 825B represents the arc length between slots 822D and 822C. In some embodiments, the arc corresponding to arc 825B is less than 30 degrees. Arc 825C represents the arc length between slots 822A and 822C. In exemplary focusing system 800B, arcs 825A and 825B are shorter (have shorter arc lengths or smaller corresponding angles) than arc 825C. In some embodiments, the arc corresponding to arc 825C is less than 180 degrees. In some embodiments, arc 825C spans approximately 120 degrees. The operation of focusing system 800B can be substantially similar to the operation of focusing system 200 described above, except that rolling member 124 rolls in a different slot 822 of backing element 820A. The angled offset nature of the slots 822 can provide additional support between the fixed tube 108 and the moving tube 106 and can help ensure that the tubes 106, 108 remain coaxial (at axis 101) during longitudinal movement of the moving tube 106 relative to the fixed tube 108, which can further reduce image drift.

[0114] Figure 9A is a perspective view of a cushioning element 900A according to another example embodiment. Figure 9B is a perspective view of another cushioning element 900B according to another example embodiment.

[0115] 9 embodiment is formed to have a plurality (e.g., eight) slots 922A-1 to 922A-8 (collectively referred to as slots 922A) defined spaced apart on the padding element 900A. The shape of the slots 922A (e.g., longitudinally extending) can be substantially similar to the shape of the slots 122a-d described above.

[0116] The cushion element 900A is formed with two sets of collinear slots defined along each edge (920A, 920B) of the cushion 900A. For example, slot 922A-1 and slot 922A-3 are arranged proximate to edge 920A and are collinear along the longitudinal direction 109. Similarly, slot 922A-2 is collinear with slot 922A-4 along the longitudinal direction 109. Slots 922A-1 and 922A-2 are positioned at substantially similar longitudinal locations along the longitudinal direction 109 and are angularly offset from one another by an arcuate distance 923. Similarly, slots 922A-3 and 922A-4 are positioned at substantially similar longitudinal locations along the longitudinal direction 109 and are angularly offset from one another by an arcuate distance 923. Slots 922A-5 through 922A-8 are arranged along edge 920B in a manner substantially similar to the arrangement of slots 922A-1 through 922A-4 along edge 920A.

[0117] 9 , the pad element 900B is shaped to define a plurality of circular slots 902 arranged along edges 920A and 920B. The circular slots 902 extend through the pad element 900B. The circular slots 902 are circular to allow a ball bearing (not shown) to rotate within the circular slots 902 about an axis of rotation that is generally perpendicular to the longitudinal direction 109 (e.g., axis 901). In some embodiments, a rolling member (e.g., ball bearing) 124 is positioned within each of the plurality of circular slots 902.

[0118] In the embodiment shown in Figure 9B, five circular slots 902 are shown on each edge 920A and 920B of the cushion element 900B. However, this is not required. Any suitable number of circular slots 902 may be arranged on each edge 920A and 920B of the cushion element 900B.

[0119] Figure 9C is a perspective view of a fixed tube 908 according to another example embodiment. Figure 9D is a perspective view of a mobile tube 906 according to another example embodiment.

[0120] In configuration 900C, the fixed tube 908 includes an outer surface 908A shaped to define a plurality of grooves 922C-1 through 922C-4 (collectively, grooves 922C). Rolling members 124 can be positioned within the grooves 922C to allow the rolling members 124 to roll within the grooves 922C along the longitudinal direction 109, thereby facilitating relative movement between the fixed tube 908 and the corresponding mobile tube. In embodiments of the fixed tube 908 incorporating the embodiment of FIG. 9C , a spacer element may or may not be used between the fixed tube 908 and the corresponding mobile tube. In configuration 900C, grooves 922C-1 and 922C-2 are substantially collinear in the longitudinal direction 109. Similarly, grooves 922C-3 and 922C-4 are substantially collinear in the longitudinal direction 109. However, this is not required. Other geometric configurations for grooves 922C, as described above with respect to slots 122, 822, 922A, and 902, are also possible.

[0121] In FIG9D , mobile tube 906 includes an inner surface 906A shaped to define grooves 922D-1 and 922D-2. Rolling members 124 can be placed in grooves 922D-1 and 922D-2 to allow rolling members 124 to roll within grooves 922D-1 and 922D-2 along longitudinal direction 109 to facilitate relative movement between mobile tube 906 and the corresponding fixed tube. In embodiments of mobile tube 906 incorporating the embodiment of FIG9D , a spacer element may or may not be used between mobile tube 906 and the corresponding fixed tube. In some embodiments, a mobile tube including grooves similar to those in FIG9D can be used with a fixed tube having grooves similar to those in FIG9C . Such grooves can be positioned so that the rolling members roll simultaneously within the grooves on both the fixed tube and the mobile tube.

[0122] Those skilled in the art will appreciate that the embodiments described herein include a moving tube as one of the inner and outer tubes of the focusing system and a fixed tube as the other of the inner and outer tubes, however, in any embodiment, this relationship can be reversed. For example, in the embodiments of Figures 3-8, the moving tube 106 is the outer tube and the fixed tube 108 is the inner tube. In some embodiments, the moving tube can be the inner tube and the fixed tube can be the outer tube. In such embodiments, a slotted pad 120 (or any other slotted and / or grooved pad described herein) and a rolling member 124 (or any other rolling member described herein) can be disposed between the outer surface of the moving (inner) tube and the aperture-defining surface of the fixed (outer) tube. Such slotted and / or grooved pads and rolling members can facilitate longitudinal movement of the moving (inner) tube relative to the fixed (outer) tube in a longitudinal direction while maintaining axial alignment of the two tubes and mitigating image drift in a manner similar to that described herein below. In such an embodiment, the orthogonal biasing system can be similar to and include similar components as the orthogonal biasing system 121 described above, but can be modified (e.g., by appropriate positional changes) to provide a force against the inner (moving) tube (having a directional component orthogonal to the orthogonal biasing system). In such an embodiment, the longitudinal force applying mechanism can be similar to and include similar components as the longitudinal force applying mechanism 119 described above, but can be modified (e.g., by appropriate positional changes) to provide a longitudinal force against the inner (moving) tube.

[0123] Explanation of terms

[0124] Throughout the specification and claims, unless the context clearly requires otherwise:

[0125] "Include", "including", etc. should be interpreted as inclusive rather than exclusive or exhaustive; that is, the meaning is "including but not limited to";

[0126] "Connect," "couple," or any variation thereof, means any direct or indirect connection or coupling between two or more elements; the connection or coupling between elements may be physical, logical, or a combination thereof;

[0127] "Herein," "above," "hereunder," and words of similar meaning, when used to describe this specification, shall refer to this specification as a whole rather than to any particular part of this specification;

[0128] · “or” when referring to a list of two or more items includes all of the following interpretations of the word: any item in the list, all items in the list, and any combination of items in the list;

[0129] The singular forms "a", "an" and "the" also include the meaning of any appropriate plural forms. Unless otherwise specified, these terms ("a", "an" and "the") mean one or more;

[0130] "And / or" is used to indicate that one or both situations may occur, for example, A and / or B includes (A and B) and (A or B);

[0131] When applied to numerical values, “approximately” means ±10% of the numerical value;

[0132] Where a feature is described as being "optional" or "optionally" present, or as being present "in some embodiments," it is intended that the disclosure encompass embodiments in which the feature is present and other embodiments in which the feature is not necessarily present, as well as other embodiments in which the feature is excluded. Furthermore, where any combination of features is described in this application, this statement is intended to serve as antecedent basis for use of exclusive terminology related to that combination of features, such as "solely," "only," and the like in connection with that combination of features and the use of "negative" or "limitations" to exclude the presence of other features.

[0133] “First” and “second” are used for descriptive purposes and should not be understood as indicating or implying relative importance or the quantity of the technical features referred to.

[0134] As used in this specification and any appended claims (if any), directional words such as "vertical," "lateral," "horizontal," "upward," "downward," "forward," "backward," "inward," "outward," "left," "right," "front," "backward," "top," "bottom," "under," "above," "below," and the like, will depend on the particular orientation of the device being described and illustrated. The subject matter described herein can assume various alternative orientations. Accordingly, these directional terms are not strictly defined and should not be interpreted narrowly.

[0135] Where a range of values ​​is specified, the range includes all subranges of that range. The statement of a range is intended to support the values ​​at the end points of the range and any intermediate values ​​to the tenth of the lower limit of the range, as well as any subrange or set of subranges of that range, and any portion of the range is specifically excluded unless the context clearly dictates otherwise. Where the stated range includes one or both of the endpoints, ranges excluding one or both of those included endpoints are also included in the invention.

[0136] For purposes of illustration, specific examples of systems, methods, and apparatus have been described herein. These are merely examples. The techniques provided herein can be applied to systems other than the example systems described above. In the practice of the present invention, many changes, modifications, additions, omissions, and substitutions are possible. The present invention includes variations of the described embodiments that will be apparent to those skilled in the art, including variations obtained by: replacing features, elements, and / or actions with equivalent features, elements, and / or actions; mixing and matching features, elements, and / or actions from different embodiments; combining features, elements, and / or actions from the embodiments described herein with features, elements, and / or actions of other technologies; and / or omitting combined features, elements, and / or actions from the described embodiments.

[0137] As will be apparent to those skilled in the art upon reading this disclosure, each of the various embodiments described and illustrated herein has discrete components and features that can be readily separated or combined with the features of any other described embodiment without departing from the scope of the invention.

[0138] Various features are described herein as being present in “some embodiments”. Such features are not mandatory and may not be present in all embodiments. Embodiments of the invention may include zero, any one, or any combination of two or more such features. Even if these features are shown in different figures and / or described in different parts or paragraphs, the present disclosure covers all possible combinations of these features. This is limited to the extent that some of such features are incompatible with other features of these features, i.e., it is impossible for a person of ordinary skill in the art to construct a practical embodiment that combines these incompatible features. Therefore, the description that “some embodiments” have feature A and “some embodiments” have feature B should be interpreted as explicitly indicating that the inventor also envisions embodiments that combine features A and B (unless the description states otherwise or features A and B are not compatible at all). This is true even if features A and B are shown in different figures and / or mentioned in different paragraphs, parts or sentences.

[0139] It is therefore intended that the following appended claims and claims introduced below be interpreted to include all such modifications, permutations, additions, omissions, and sub-combinations as can reasonably be inferred. The scope of the claims should not be limited to the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the entire description.

[0140] The embodiments of the present invention described above are intended to be exemplary only. Accordingly, the scope of the present invention is intended to be limited solely by the scope of the appended claims.

Claims

1. A focusing device for an optical instrument such as a telescope, the focusing device comprising: a first tube extending in a longitudinal direction; a second tube extending in the longitudinal direction, the second tube including a bore-defining surface shaped to define a bore extending in the longitudinal direction, wherein the first tube extends into the bore; an optical element coupled to one of the first tube and the second tube to move therewith; a spacer element positioned between an outer surface of the first tube and a bore-defining surface of the second tube, the spacer element being shaped to define a plurality of slots therethrough; a plurality of rolling members, at least one rolling member disposed in each slot to contact an outer surface of the first tube and a bore-defining surface of the second tube; Relative movement between the first and second tubes in the longitudinal direction is facilitated by rolling movement of the rolling members in their respective slots along the outer surface of the first tube and the bore-defining surface of the second tube in the longitudinal direction.

2. A focusing device according to claim 1 or any other claim herein, wherein: The slots and the rolling members are shaped such that the slots restrict the rolling members from moving with their respective slots.

3. A focusing apparatus according to any one of claims 1 and 2 or any other claim herein, wherein: The slots extend in the longitudinal direction, and wherein the slots and the rolling members are shaped such that the slots guide the rolling members in rolling motion that is substantially confined to the longitudinal direction within their respective slots.

4. The focusing device of claims 1 and 2 or any other claim herein, wherein the slot is circular.

5. A focusing device according to any one of claims 1 to 4 or any other claim herein, wherein the plurality of slots include at least a first pair of slots spaced apart from each other in the longitudinal direction and at least a second pair of slots spaced apart from each other in an angular direction about the longitudinal extension axis.

6. A focusing apparatus according to any one of claims 1 to 5 or any other claim herein, wherein: At least one of the position and shape of the slots is such that rolling movement of the rolling members in their respective slots along the outer surface of the first tube and the hole-defining surface of the second tube in the longitudinal direction maintains the first tube and the second tube in a substantially coaxial relationship, thereby mitigating image drift.

7. A focusing apparatus according to claim 5 or any other claim herein, wherein: At least one of the position and shape of the slots is such that rolling motion of the rolling members in their respective slots in the longitudinal direction maintains the first tube and the second tube in a substantially coaxial relationship along the outer surface of the first tube and the hole-defining surface of the second tube, thereby mitigating image drift.

8. A focusing device according to any one of claims 1 to 7 or any other claim herein, wherein the contact between the rolling member and the outer surface of the first tube and the contact between the rolling member and the hole-defining surface of the second tube are maintained in the space between the outer surface of the first tube and the hole-defining surface of the second tube.

9. A focusing apparatus according to claim 8 or any other claim herein, wherein: The space between the outer surface of the first tube and the hole-defining surface of the second tube has a circular cross-sectional shape in a cross section orthogonal to the longitudinal direction.

10. A focusing apparatus according to any one of claims 1 to 9 or any other claim herein, wherein the rolling member comprises a ball bearing.

11. A focusing apparatus according to any one of claims 1 to 9 or any other claim herein, wherein the rolling members comprise cylindrical rollers (eg, wheels).

12. The focusing device of any one of claims 1 to 11 or any other claim herein, wherein the plurality of grooves comprises at least four grooves.

13. The focusing device of any one of claims 1 to 12 or any other claim herein, wherein the plurality of grooves comprises 8 to 10 grooves.

14. A focusing device according to any one of claims 1 to 13 or any other claim herein, wherein at least some of the plurality of slots are arranged to be collinear with each other in the longitudinal direction and to be spaced apart from each other.

15. A focusing device according to any one of claims 1 to 14 or any other claim herein, wherein at least two groups of slots in the plurality of slots are arranged to be collinear with each other in the longitudinal direction and spaced apart from each other.

16. A focusing device according to any one of claims 1 to 15 or any other claim herein, wherein at least some of the plurality of slots are arranged to be located at the same position in the longitudinal direction and are angularly spaced apart from each other around the longitudinal extension axis.

17. A focusing device according to any one of claims 1 to 16 or any other claim herein, wherein at least two groups of slots among the plurality of slots are arranged to be located at the same position in the longitudinal direction and are angularly spaced apart from each other around the longitudinal extension axis.

18. A focusing device according to any one of claims 1 to 17 or any other claim herein, wherein the pad element is semi-tubular and extends in the longitudinal direction, having a semi-annular cross-section in a plane orthogonal to the longitudinal direction, and the arc corresponding to the semi-annular cross-section is less than 360°.

19. The focusing apparatus of claim 18 or any other claim herein, wherein the arc is in the range of approximately 45°-180°.

20. The focusing apparatus of claim 19 or any other claim herein, wherein the arc is in the range of approximately 75°-150°.

21. A focusing apparatus according to any one of claims 1 to 20 or any other claim herein, comprising an orthogonal biasing system operable to apply an orthogonal force to the second tube, the orthogonal force oriented to have a component orthogonal to the longitudinal direction, the orthogonal force maintaining contact between the rolling member and the outer surface of the first tube and contact between the rolling member and the hole-defining surface of the second tube, and maintaining the first tube and the second tube in a substantially coaxial relationship, thereby mitigating image drift.

22. A focusing apparatus according to any one of claims 1 to 20 or any other claim herein, comprising an orthogonal biasing system operable to apply an orthogonal force to the first tube, the orthogonal force oriented to have a component orthogonal to the longitudinal direction, the orthogonal force maintaining contact between the rolling member and the outer surface of the first tube and contact between the rolling member and the hole-defining surface of the second tube, and maintaining the first tube and the second tube in a substantially coaxial relationship, thereby mitigating image drift.

23. A focusing arrangement according to any one of claims 21 to 22 or any other claim herein, wherein: The quadrature biasing system includes a biasing mechanism comprising a compression spring and a pressure plate, the pressure plate being directly or indirectly connected to a base of the focusing device via another fixed component.

24. A focusing apparatus according to claim 23 or any other claim herein, wherein: The pressure plate is adjustably coupled to the base to control the amount of normal force applied by the normal biasing system.

25. The focusing apparatus of any one of claims 21 to 22 or any other claim herein, wherein the quadrature bias system further comprises: a friction block coupled to one of the first tube and the second tube, the friction block including a friction surface; a focus adjustment shaft in contact with the friction surface and supported for rotation about a focus adjustment axis substantially orthogonal to the longitudinal direction; A biasing mechanism for applying a second force that urges the focus adjustment shaft against the friction surface and thereby generates the normal force.

26. A focusing apparatus according to claim 25 or any other claim herein, wherein: The biasing system includes a biasing mechanism including a compression spring and a pressure plate, which is directly or indirectly connected to the base of the focusing device through another fixed component.

27. A focusing apparatus according to claim 26 or any other claim herein, wherein: The pressure plate is adjustably coupled to the base to control the amount of normal force applied by the normal biasing system.

28. A focusing apparatus according to any one of claims 25 to 27 or any other claim herein, wherein the second force is directed in a direction substantially orthogonal to both the longitudinal direction and the focus adjustment axis.

29. A focusing apparatus according to claim 25 or any other claim herein, wherein the second force is oriented in a direction having a component orthogonal to both the longitudinal direction and the focus adjustment axis.

30. A focusing apparatus according to any one of claims 25 to 29 or any other claim herein, comprising a shaft support block defining a recess, wherein: The focus adjustment shaft is supported in the recess by the shaft support block.

31. A focusing device according to any one of claims 25 to 29 or any other claim herein, comprising one or more pivot joints, and wherein the focus adjustment shaft is supported by the one or more pivot joints for rotation about the focus adjustment axis.

32. A focusing device according to any one of claims 21 to 31 or any other claim herein, wherein the orthogonal force helps to promote rolling movement of the rolling members in their respective slots in the longitudinal direction along the outer surface of the first tube and the hole-defining surface of the second tube.

33. A focusing apparatus according to any one of claims 21 to 32 or any other claim herein, wherein: The normal force helps mitigate sliding motion of the rolling member along the outer surface of the first tube and the bore-defining surface of the second tube.

34. A focusing apparatus according to any one of claims 25 to 33 or any other claim herein, comprising a longitudinal force applying mechanism connected to provide a force to cause relative movement between the first tube and the second tube in the longitudinal direction.

35. The focusing apparatus of claim 34 or any other claim herein, wherein the longitudinal force applying mechanism comprises the friction block, the focus adjustment shaft, and the biasing mechanism.

36. A focusing device for an optical instrument such as a telescope, the focusing device comprising: a first tube extending in a longitudinal direction; a second tube extending in the longitudinal direction, the second tube including a bore-defining surface shaped to define a bore extending in the longitudinal direction, wherein the first tube extends into the bore; an optical element coupled to one of the first tube and the second tube to move therewith; at least one of the outer surface of the first tube and the bore-defining surface of the second tube is shaped to define a plurality of grooves; a plurality of rolling members, at least one rolling member being disposed in each groove to contact an outer surface of the first tube and a bore-defining surface of the second tube; wherein relative movement between the first and second tubes in the longitudinal direction is facilitated by rolling movement of the rolling members in their respective grooves along the outer surface of the first tube and the hole-defining surface of the second tube in the longitudinal direction.

37. A focusing apparatus according to claim 36 or any other claim herein, wherein: the outer surface of the first tube being shaped to define a first plurality of grooves; the bore-defining surface of the second tube being shaped to define a second plurality of grooves; At least one rolling member is disposed in each groove of the first plurality of grooves and in each groove of the second plurality of grooves.

38. A focusing device according to any one of claims 36 to 37 or any other claim herein, wherein the grooves and the rolling members are shaped such that the grooves restrict movement of the rolling members in their respective grooves.

39. A focusing device according to any one of claims 36 to 38 or any other claim herein, wherein the grooves extend in the longitudinal direction, and wherein the grooves and the rolling members are formed so that the grooves guide the rolling members in rolling motion, the rolling motion being substantially confined to the longitudinal direction within their respective grooves.

40. A focusing device according to any one of claims 36 to 39 or any other claim herein, wherein the plurality of grooves comprises at least a first pair of grooves spaced apart from each other in the longitudinal direction and at least a second pair of grooves spaced apart from each other in an angular direction about the longitudinal extension axis.

41. A focusing device according to any one of claims 36 to 40 or any other claim herein, wherein at least one of the position and shape of the grooves causes the rolling movement of the rolling members in their respective grooves along the outer surface of the first tube and the hole-defining surface of the second tube in the longitudinal direction to maintain the first tube and the second tube in a substantially coaxial relationship, thereby reducing image drift.

42. A focusing device according to claim 40 or any other claim herein, wherein at least one of the position and shape of the grooves causes the rolling movement of the rolling members in their respective grooves along the outer surface of the first tube and the hole-defining surface of the second tube in the longitudinal direction to maintain the first tube and the second tube in a substantially coaxial relationship along the longitudinal extension axis, thereby reducing image drift.

43. A focusing device according to any one of claims 36 to 43 or any other claim herein, wherein the contact between the rolling member and the outer surface of the first tube and the contact between the rolling member and the hole-defining surface of the second tube maintain a space between the outer surface of the first tube and the hole-defining surface of the second tube.

44. A focusing device according to claim 43 or any other claim herein, wherein the space between the outer surface of the first tube and the hole-defining surface of the second tube has an annular cross-sectional shape in a cross section orthogonal to the longitudinal direction.

45. A focusing apparatus according to any one of claims 36 to 44 or any other claim herein, wherein the rolling member comprises a ball bearing.

46. ​​A focusing apparatus according to any one of claims 36 to 44 or any other claim herein, wherein the rolling members comprise cylindrical rollers (eg wheels).

47. A focusing device according to any one of claims 36 to 46 or any other claim herein, comprising an orthogonal biasing system operable to apply an orthogonal force to the second tube, the orthogonal force oriented to have a component orthogonal to the longitudinal direction, the orthogonal force maintaining contact between the rolling members and their respective grooves and maintaining the first tube and the second tube in a substantially coaxial relationship, thereby reducing image drift.

48. A focusing apparatus according to any one of claims 36 to 46 or any other claim herein, comprising an orthogonal biasing system operable to apply an orthogonal force to the first tube, the orthogonal force oriented to have a component orthogonal to the longitudinal direction, the orthogonal force maintaining contact between the rolling members and their respective grooves and maintaining the first tube and the second tube in a substantially coaxial relationship, thereby mitigating image drift.

49. A focusing device according to any one of claims 47 to 48 or any other claim herein, wherein the orthogonal biasing system comprises a biasing mechanism comprising a compression spring and a pressure plate connected directly or indirectly to a base of the focusing device via another component.

50. The focusing apparatus of claim 49 or any other claim herein, wherein: The pressure plate is adjustably coupled to the base to control the amount of normal force applied by the normal biasing system.

51. The focusing apparatus of any one of claims 47 to 50 or any other claim herein, wherein the quadrature bias system further comprises: a friction block coupled to one of the first tube and the second tube, the friction block including a friction surface; a focus adjustment shaft in contact with the friction surface and supported for rotation about a focus adjustment axis substantially orthogonal to the longitudinal direction; A biasing mechanism for applying a second force that urges the focus adjustment shaft against the friction surface and thereby generates the normal force.

52. The focusing apparatus of claim 51 or any other claim herein, wherein: The biasing system includes a biasing mechanism including a compression spring and a pressure plate connected directly or indirectly to a base of the focusing device through another component.

53. A focusing apparatus according to claim 52 or any other claim herein, wherein the pressure plate is adjustably connected to the base to control the amount of orthogonal force applied by the orthogonal biasing system.

54. A focusing device according to any one of claims 51 to 53 or any other claim herein, wherein the normal force helps to maintain contact between the rolling member and the outer surface of the first tube and the hole defining surface of the second tube.

55. A focusing device according to any one of claims 51 to 54 or any other claim herein, wherein the normal force helps to promote rolling movement of the rolling members in their respective grooves in the longitudinal direction.

56. A focusing device according to any one of claims 51 to 55 or any other claim herein, wherein the force helps to mitigate sliding movement of the rolling members in their respective grooves.

57. A focusing device for an optical instrument such as a telescope, the focusing device comprising: a first tube extending in a longitudinal direction; a second tube extending in the longitudinal direction, the second tube including a bore-defining surface shaped to define a bore extending in the longitudinal direction, wherein the first tube extends into the bore; an optical element coupled to one of the first tube and the second tube to move therewith; a spacer element positioned between an outer surface of the first tube and a bore-defining surface of the second tube, the spacer element being shaped to define a plurality of grooves in a surface thereof; a plurality of rolling members, at least one rolling member disposed in each groove to contact the spacer element surface and one of the outer surface of the first tube and the bore-defining surface of the second tube; Wherein relative movement between the first tube and the second tube in the longitudinal direction is facilitated by rolling movement of the rolling members in their respective grooves along the surface of the spacer element and one of the outer surface of the first tube and the hole defining surface of the second tube in the longitudinal direction.

58. The focusing apparatus of claim 57 or any other claim herein, wherein: said one of the outer surface of the first tube and the bore-defining surface of the second tube being shaped to define a second plurality of grooves; At least one rolling member is disposed in each groove of the plurality of grooves and each groove of the second plurality of grooves.

59. A focusing device according to any one of claims 57 to 58 or any other claim herein, wherein the grooves and the rolling members are shaped such that the grooves restrict movement of the rolling members in their respective grooves.

60. A focusing device according to any one of claims 57 to 59 or any other claim herein, wherein the grooves extend along the longitudinal direction, and wherein the grooves and the rolling members are formed so that the grooves guide the rolling members in rolling motion, the rolling motion being substantially confined to the longitudinal direction within their respective grooves.

61. A focusing device according to any one of claims 57 to 60 or any other claim herein, wherein the plurality of grooves comprises at least a first pair of grooves spaced apart from each other in the longitudinal direction and at least a second pair of grooves spaced apart from each other in an angular direction about the longitudinal extension axis.

62. A focusing device according to any one of claims 57 to 61 or any other claim herein, wherein at least one of the position and shape of the grooves is such that rolling movement of the rolling members in their respective grooves along the outer surface of the first tube and the hole-defining surface of the second tube in the longitudinal direction maintains the first tube and the second tube in a substantially coaxial relationship, thereby reducing image drift.

63. A focusing device according to claim 61 or any other claim herein, wherein at least one of the position and shape of the grooves causes the rolling movement of the rolling members in their respective grooves along the outer surface of the first tube and the hole-defining surface of the second tube in the longitudinal direction to maintain the first tube and the second tube in a substantially coaxial relationship along the longitudinal extension axis, thereby reducing image drift.

64. A focusing device according to any one of claims 57 to 63 or any other claim herein, wherein the contact between the rolling member and the surface of the cushioning element and the contact between the rolling member and the outer surface of the first tube and one of the hole-defining surfaces of the second tube maintain a space between the outer surface of the first tube and the hole-defining surface of the second tube.

65. The focusing apparatus of claim 64 or any other claim herein, wherein: The space between the outer surface of the first tube and the hole-defining surface of the second tube has a circular cross-sectional shape in a cross section orthogonal to the longitudinal direction.

66. A focusing device according to any one of claims 57 to 65 or any other claim herein, wherein the rolling member comprises a ball bearing.

67. A focusing apparatus according to any one of claims 57 to 65 or any other claim herein, wherein the rolling members comprise cylindrical rollers (e.g., wheels).

68. A focusing device according to any one of claims 57 to 67 or any other claim herein, wherein the padding element is semi-tubular and extends in the longitudinal direction, and has a semi-circular cross-section in a plane orthogonal to the longitudinal direction, and the arc corresponding to the semi-circular cross-section is less than 360°.

69. A focusing device according to any one of claims 57 to 68 or any other claim herein, comprising an orthogonal biasing system operable to apply an orthogonal force to the second tube, the orthogonal force oriented to have a component orthogonal to the longitudinal direction, the orthogonal force maintaining contact between the rolling members and their respective grooves and maintaining the first tube and the second tube in a substantially coaxial relationship, thereby reducing image drift.

70. A focusing device according to any one of claims 57 to 68 or any other claim herein, comprising an orthogonal biasing system operable to apply an orthogonal force to the first tube, the orthogonal force oriented to have a component orthogonal to the longitudinal direction, the orthogonal force maintaining contact between the rolling members and their respective grooves and maintaining the first tube and the second tube in a substantially coaxial relationship, thereby reducing image drift.

71. A focusing device according to any one of claims 69 to 70 or any other claim herein, wherein the orthogonal biasing system comprises a biasing mechanism comprising a compression spring and a pressure plate connected directly or indirectly to a base of the focusing device via another component.

72. The focusing apparatus of claim 71 or any other claim herein, wherein: The pressure plate is adjustably coupled to the base to control the amount of normal force applied by the normal biasing system.

73. The focusing apparatus of any one of claims 69 to 72 or any other claim herein, wherein the quadrature bias system further comprises: a friction block coupled to one of the first tube and the second tube, the friction block including a friction surface; a focus adjustment shaft in contact with the friction surface and supported for rotation about a focus adjustment axis substantially orthogonal to the longitudinal direction; A biasing mechanism for applying a second force that urges the focus adjustment shaft against the friction surface and thereby generates the normal force.

74. A focusing device according to claim 73 or any other claim herein, wherein the biasing system includes a biasing mechanism, the biasing mechanism including a compression spring and a pressure plate, which is directly or indirectly connected to the base of the focusing device through another component.

75. The focusing apparatus of claim 74 or any other claim herein, wherein: The pressure plate is adjustably coupled to the base to control the amount of normal force applied by the normal biasing system.

76. A focusing device according to any one of claims 73 to 75 or any other claim herein, wherein the normal force helps to maintain contact between the rolling member and the outer surface of the first tube and the hole defining surface of the second tube.

77. A focusing device according to any one of claims 73 to 76 or any other claim herein, wherein the normal force helps to promote rolling movement of the rolling members in their respective grooves in the longitudinal direction.

78. A focusing apparatus according to any one of claims 73 to 77 or any other claim herein, wherein: The normal forces help to mitigate sliding motion of the rolling members in their respective grooves.

79. A method for focusing an optical instrument such as a telescope, the method comprising: providing a first tube extending in a longitudinal direction; providing a second tube extending in the longitudinal direction, the second tube including a bore-defining surface shaped to define a bore extending in the longitudinal direction, wherein the first tube extends into the bore; providing an optical element coupled to one of the first tube and the second tube for movement therewith; providing a spacer element positioned between an outer surface of the first tube and a bore-defining surface of the second tube, the spacer element being shaped to define a plurality of slots therethrough; providing a plurality of rolling members, at least one rolling member disposed in each slot to contact an outer surface of the first tube and a bore-defining surface of the second tube; Relative movement between the first and second tubes in the longitudinal direction is facilitated by rolling movement of the rolling members in their respective slots along the outer surface of the first tube and the bore-defining surface of the second tube in the longitudinal direction.

80. A method for focusing an optical instrument such as a telescope, the method comprising: providing a first tube extending in a longitudinal direction; providing a second tube extending in the longitudinal direction, the second tube including a bore-defining surface shaped to define a bore extending in the longitudinal direction, wherein the first tube extends into the bore; providing an optical element coupled to one of the first tube and the second tube for movement therewith; providing at least one of an outer surface of the first tube and a bore-defining surface of the second tube shaped to define a plurality of grooves; providing a plurality of rolling members, at least one rolling member being disposed in each groove to contact an outer surface of the first tube and a bore-defining surface of the second tube; Relative movement between the first and second tubes in the longitudinal direction is facilitated by rolling movement of the rolling members in their respective grooves along the outer surface of the first tube and the bore-defining surface of the second tube in the longitudinal direction.

81. A method for focusing an optical instrument such as a telescope, the method comprising: providing a first tube extending in a longitudinal direction; providing a second tube extending in the longitudinal direction, the second tube including a bore-defining surface shaped to define a bore extending in the longitudinal direction, wherein the first tube extends into the bore; providing an optical element coupled to one of the first tube and the second tube for movement therewith; providing a spacer element positioned between an outer surface of the first tube and a bore-defining surface of the second tube, the spacer element being shaped to define a plurality of grooves in a surface thereof; providing a plurality of rolling members, at least one rolling member disposed in each groove to contact the spacer element surface and one of the outer surface of the first tube and the bore-defining surface of the second tube; Relative movement between the first and second tubes in the longitudinal direction is facilitated by rolling movement of the rolling members in their respective grooves along the spacer element surface and one of the outer surface of the first tube and the bore-defining surface of the second tube in the longitudinal direction.

82. A method according to any one of claims 79 to 81 , comprising method features corresponding to any one of claims 1 to 78.

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