Abstract: An optical instrument comprises: an openable housing and a cover portion which together define an optical path cavity through which light travels for operation of the optical instrument; and one or more optical components mounted to the openable cover portion and located within or at least partially within the optical path cavity. The openable housing defines a housing aperture. The cover portion is moveable relative to the openable housing between: a closed position where the cover portion is located to cover the housing aperture to visually conceal the one or more optical components or at least portions of the one or more optical components; and an open position where the cover portion is located to uncover the housing aperture and visually expose the one or more optical elements or at least portions of the one or more optical components via the housing aperture.

Abstract: An optical instrument comprises: an openable housing and a cover portion which together define an optical path cavity through which light travels for operation of the optical instrument; and one or more optical components mounted to the openable cover portion and located within or at least partially within the optical path cavity. The openable housing defines a housing aperture. The cover portion is moveable relative to the openable housing between: a closed position where the cover portion is located to cover the housing aperture to visually conceal the one or more optical components or at least portions of the one or more optical components; and an open position where the cover portion is located to uncover the housing aperture and visually expose the one or more optical elements or at least portions of the one or more optical components via the housing aperture.

Abstract: A method for manufacturing a mirror blank comprises: providing a primary piece of glass comprising a primary planar surface and a backing piece of glass comprising a backing planar surface; assembling a mirror blank assembly, wherein assembling the mirror blank assembly comprises interposing a plurality of glass splines between the primary glass and the backing glass. Interposing the plurality of glass splines comprises: for each glass spline, respectively abutting first and second opposed surfaces of the glass spline against the primary planar surface of the primary glass and against the backing planar surface of the backing glass. The mirror blank assembly is then heated to fuse the interposed glass splines to the primary glass and the backing glass while the primary glass and the secondary glass remain spaced apart from one another by the interposed glass splines to thereby provide the mirror blank.

Abstract: Apparatus and methods are provided for time-lapse astrophotography. One embodiment of the invention comprises a method for capturing a time-lapse image sequence. The method comprises capturing a first plurality of photographs, wherein capturing each photograph of the first plurality of photographs comprises opening a shutter of an image-capture device; while the shutter of the image-capture device is open, moving the image-capture device to reduce the movement of a celestial object or coordinate within the field of view of the image-capture device; closing the shutter of the image-capture device; and moving the image-capture device to a subsequent orientation.

Abstract: A method for manufacturing a mirror blank comprises: providing a primary piece of glass comprising a primary planar surface and a backing piece of glass comprising a backing planar surface; assembling a mirror blank assembly, wherein assembling the mirror blank assembly comprises interposing a plurality of glass splines between the primary glass and the backing glass. Interposing the plurality of glass splines comprises: for each glass spline, respectively abutting first and second opposed surfaces of the glass spline against the primary planar surface of the primary glass and against the backing planar surface of the backing glass. The mirror blank assembly is then heated to fuse the interposed glass splines to the primary glass and the backing glass while the primary glass and the secondary glass remain spaced apart from one another by the interposed glass splines to thereby provide the mirror blank.

Abstract: A method for manufacturing an etalon is disclosed. The method comprises arranging a plurality of first spacers between a flat surface of a first optical plate and a concave surface of a second optical plate. For each of the spacers, the flat surface bears on a first abutment surface of the spacer and the concave surface bears on a second abutment surface of the spacer. The concave surface is deformed to be parallel to the second abutment surfaces. For each of the spacers, the flat surface is bonded to the first abutment surface and the concave surface is bonded to the second abutment surface.

Abstract: A method for manufacturing a mirror blank comprises: providing a primary piece of glass comprising a primary planar surface and a backing piece of glass comprising a backing planar surface; assembling a mirror blank assembly, wherein assembling the mirror blank assembly comprises interposing a plurality of glass splines between the primary glass and the backing glass. Interposing the plurality of glass splines comprises: for each glass spline, respectively abutting first and second opposed surfaces of the glass spline against the primary planar surface of the primary glass and against the backing planar surface of the backing glass. The mirror blank assembly is then heated to fuse the interposed glass splines to the primary glass and the backing glass while the primary glass and the secondary glass remain spaced apart from one another by the interposed glass splines to thereby provide the mirror blank.

Abstract: An apparatus for providing a frameless hollow roof mirror comprises: a first element having a first mirrored surface and a first abutment surface; a second element having a second mirrored surface and a second abutment surface, the first and second elements arranged in a roof mirror configuration wherein the second abutment surface abuts against the first abutment surface and the first and second mirrored surfaces meet at a generally linear junction and are oriented relative to one another at a desired roof mirror angle; and a plurality of fasteners extending through the first and second abutment surfaces. The plurality of fasteners exerts a force to cause the first and second abutment surfaces to bear against each other.

Abstract: A method for manufacturing an etalon is disclosed. The method comprises arranging a plurality of first spacers between a flat surface of a first optical plate and a concave surface of a second optical plate. For each of the spacers, the flat surface bears on a first abutment surface of the spacer and the concave surface bears on a second abutment surface of the spacer. The concave surface is deformed to be parallel to the second abutment surfaces. For each of the spacers, the flat surface is bonded to the first abutment surface and the concave surface is bonded to the second abutment surface.

Abstract: A method for manufacturing a mirror blank comprises: providing a primary piece of glass comprising a primary planar surface and a backing piece of glass comprising a backing planar surface; assembling a mirror blank assembly, wherein assembling the mirror blank assembly comprises interposing a plurality of glass splines between the primary glass and the backing glass. Interposing the plurality of glass splines comprises: for each glass spline, respectively abutting first and second opposed surfaces of the glass spline against the primary planar surface of the primary glass and against the backing planar surface of the backing glass. The mirror blank assembly is then heated to fuse the interposed glass splines to the primary glass and the backing glass while the primary glass and the secondary glass remain spaced apart from one another by the interposed glass splines to thereby provide the mirror blank.

Abstract: An object-finder-mounting apparatus comprises: a base for mounting the object-finder-mounting apparatus to an optical instrument; an object-finder-holder assembly coupled to the base and comprising one or more object-finder holders for removably holding an object finder; a projection plate moveably coupled to the base and/or the object-finder-holder assembly for movement between first and second positions; and a shadow-casting member. The object-finder-mounting apparatus is convertible between first and second working modes. In the first working mode, the projection plate is moved to the first position which permits use of the object finder held by the object-finder holders to locate objects. In the second working mode, the object finder is removed from the object-finder holders and the projection plate is moved to the second position. In the second working mode, the shadow-casting member casts a shadow onto the projection plate when the optical instrument is directed toward a luminous object.

Abstract: Apparatus and methods are provided for time-lapse astrophotography. One embodiment of the invention comprises a method for capturing a time-lapse image sequence. The method comprises capturing a first plurality of photographs, wherein capturing each photograph of the first plurality of photographs comprises opening a shutter of an image-capture device; while the shutter of the image-capture device is open, moving the image-capture device to reduce the movement of a celestial object or coordinate within the field of view of the image-capture device; closing the shutter of the image-capture device; and moving the image-capture device to a subsequent orientation.

Abstract: A container for housing optical instruments is described. The container includes a case having an interior surface shaped to define a container cavity for holding an optical instrument. The interior surface is further shaped to define a plurality of ball-receiving concavities which open into the container cavity. Each ball-receiving concavity is shaped to have an opening at its edge and an interior region. The container also includes a plurality of elastically deformable balls, each ball located in a corresponding ball-receiving concavity and projecting from the interior region of the corresponding ball-receiving concavity through the opening and into the container cavity such that the balls are deformed to accommodate the optical instrument in the container cavity.

Abstract: An apparatus for providing a frameless hollow roof mirror comprises: a first element having a first mirrored surface and a first abutment surface; a second element having a second mirrored surface and a second abutment surface, the first and second elements arranged in a roof mirror configuration wherein the second abutment surface abuts against the first abutment surface and the first and second mirrored surfaces meet at a generally linear junction and are oriented relative to one another at a desired roof mirror angle; and a plurality of fasteners extending through the first and second abutment surfaces. The plurality of fasteners exerts a force to cause the first and second abutment surfaces to bear against each other.

Abstract: A container for housing optical instruments is described. The container includes a case having an interior surface shaped to define a container cavity for holding an optical instrument. The interior surface is further shaped to define a plurality of ball-receiving concavities which open into the container cavity. Each ball-receiving concavity is shaped to have an opening at its edge and an interior region. The container also includes a plurality of elastically deformable balls, each ball located in a corresponding ball-receiving concavity and projecting from the interior region of the corresponding ball-receiving concavity through the opening and into the container cavity such that the balls are deformed to accommodate the optical instrument in the container cavity.

Abstract: A multi-layer mirror comprising a front plate, a backing plate and spacers coupled between the front plate and the backing plate. The spacers are closely packed with one another and arranged in a manner where adjacent spacers contact one another and packing spaces are defined between groups of spacers in contact with one another. Each of the spacers comprises a plurality of ventilation holes extending between a bore of the spacer and an exterior of the spacer. For each spacer, the plurality of ventilation holes comprises a first ventilation hole in fluid communication with a first packing space defined at least in part by the spacer and a second ventilation hole, spaced apart from the first ventilation hole and in fluid communication with a second packing space defined at least in part by the spacer.

Abstract: Method and apparatus are provided for a hand-held planetarium which displays a sky pattern comprising graphical representations of celestial objects. A sensing system comprising sensors provides information about an orientation of the device. A controller receives such information and determines an altitude angle of a pointing axis and an azimuthal angle of the pointing axis. The controller accesses a database of celestial objects and determines celestial objects for display based at least in part on a measure of proximity of the celestial objects to the pointing axis. Graphical representations of the celestial objects are displayed on a screen. Additional information for the celestial objects is displayed on the screen over a plurality of display slices. Based at least in part on sensed orientation information, the orientation of a motorized telescope is controlled so that the celestial objects displayed on the screen come within the telescope's field of view.

Abstract: An alt-az mount for supporting and orienting optical instruments comprises: a generally horizontally extending arm couple to a level surface by an azimuthal pivot joint which permits pivotal movement of the horizontally extending arm with respect to the level surface about a vertical azimuthal axis; a generally vertically extending arm pivotally coupled to the horizontally extending arm by an inter-arm pivot joint which permits pivotal movement of the vertically extending arm with respect to the horizontally extending arm about a vertical inter-arm axis; and an instrument coupling mechanism for coupling the mount to an optical instrument, the instrument coupling mechanism comprising an altitude pivot joint which permits pivotal movement of the optical instrument with respect to the vertically extending arm about a horizontal altitude axis.

Abstract: Method and apparatus are provided for a hand-held planetarium which displays a sky pattern comprising graphical representations of one or more celestial objects. A sensing system comprising one or more sensors provides information about an orientation of the device. A controller receives the information about the orientation of the device from the sensing system and determines therefrom an altitude angle of a pointing axis and an azimuthal angle of the pointing axis. The controller accesses a database of celestial objects and determines, from within the database, one or more selected celestial objects for display based at least in part on a measure of proximity of the celestial objects to the pointing axis. Graphical representations of the one or more selected celestial objects are displayed on a display screen. The planetarium may switch between a normal orientation mode and a downward facing orientation mode.

Abstract: An object-finder-mounting apparatus comprises: a base for mounting the object-finder-mounting apparatus to an optical instrument; an object-finder-holder assembly coupled to the base and comprising one or more object-finder holders for removably holding an object finder; a projection plate moveably coupled to the base and/or the object-finder-holder assembly for movement between first and second positions; and a shadow-casting member. The object-finder-mounting apparatus is convertible between first and second working modes. In the first working mode, the projection plate is moved to the first position which permits use of the object finder held by the object-finder holders to locate objects. In the second working mode, the object finder is removed from the object-finder holders and the projection plate is moved to the second position. In the second working mode, the shadow-casting member casts a shadow onto the projection plate when the optical instrument is directed toward a luminous object.