Abstract: A lens barrel includes a fixed tube, a moving tube arranged to move in the direction of an optical axis over the outer circumference of the fixed tube and to have a cutout part, and a band-like circuit board disposed around the optical axis on the outside of the fixed tube and having a part located inside the moving tube within an area corresponding to the cutout part and a part located outside the moving tube within an area other than the area corresponding to the cutout part.

Abstract: An adaptor detachably mounted on an ocular of night vision goggles for quly adjusting the objective lens focus to clearly view far and near objects. The adaptor includes a positive optical power or close-up lens mounted in a holder pivotally mounted between a stowed, inoperative position and an operative position locating the close-up lens in axial alignment with the objective lens of the ocular. The close-up lens has an effective diameter substantially smaller than the diameter of the objective lens to raise the F/number of the objective lens/close-up lens combination for increasing the depth of focus for enhanced near viewing. Auxiliary illumination is provided by a battery powered infra-red Light Emitting Diode (LED) mounted in the adaptor and energized by a switch as the lens holder moves toward its operative position.

Abstract: A night vision monocular that includes an objective lens subassembly for receiving low intensity and/or infrared light. The objective lens subassembly focuses the light onto an image intensifier tube that converts the light into a visible image. The visible image passes through a collimator subassembly that collimates the visible image. Finally, the collimated image is viewed through an eyepiece subassembly. The objective lens subassembly, image intensifier tube, collimator subassembly and eyepiece subassembly are each separately manufactured subassemblies that are encased in subhousings and are ready to be assembled into a larger optical device. The housing of the present invention night vision monocular is a two piece structure, having a first half and an opposite second half. Partitions extend inwardly from a plurality of locations on both halves of the housing. The partitions are contoured and positioned to abut against and retain the various subassemblies within the night vision device.

Abstract: A lens 2 is mechanically connected to an image processor 3 having a different mount from that of the lens 2 via a converting adapter 1. A computer 4 is electrically connected to the converting adapter 1 and the lens 2 via electrical terminals 6 and 7. A command transmitted from the computer 4 is converted by an internal converter 8 of the converting adapter 1. The computer 4 controls an internal actuator 2c of the lens 2 by transmitting a command through communication.

Abstract: An electric revolver apparatus of a microscope comprises a revolver holding a plurality of objective lenses, a drive device for driving and braking the revolver based on a command signal from the outside of the electric revolver apparatus, a detection device for detecting a predetermined amount of rotation of the revolver and outputting a detection signal to brake the drive device, and a delay circuit for delaying the detection signal for a predetermined period of time and outputting it to the outside to delay the brake starting time of the drive device based on the command signal from the outside.

Abstract: A magnetically actuated optical focusing device is provided. The focusing device comprises a housing with an optical component being displaceably and rotatably arranged therein. The optical component is ferromagnetically coupled, via an internal magnet arranged thereon, to an external magnet arranged outside of the housing, the external magnet being fixed to a focusing ring which is rotatably mounted on the housing. When the focusing ring is rotated, the ferromagnetic attraction between the magnets is sufficient to drive the internal magnet through a helical channel defined on the internal surface of the housing, thus causing the optical component to be longitudinally displaced within the housing. The helical channel exerts sufficient restraining force on the inner magnet so that the inner magnet remains in a particular position along the channel even if the ferromagnetic coupling between the magnets is broken down.

Abstract: A mounting adapter for coupling a TV lens or other type of lens to a night vision device is provided. The mounting adapter is a longitudinal tubular member that has an exterior surface that tapers from a wider first end to a narrower second end. The interior surface of the wider first end includes a first threaded region to removably couple the mounting adapter to a night vision device. A second threaded region is located on the interior surface of the narrower second end for removably coupling a TV lens or other optical device to the mounting adapter. The mounting adapter defines a cavity for receiving a portion of an image intensifier tube, this cavity being located just past the first threaded region. At the end of the cavity there is defined an annular-shaped seat which abuts against the image intensifier tube when the mounting adapter is coupled to the night vision device.

Abstract: A lens apparatus, such as a lens barrel for a camera, allows different optical systems to be easily removed and installed. The lens apparatus has first and second optical systems with an optical axis of the lens apparatus extending thorough the first and second optical systems. First and second lens compartments respectively retain the first and second optical systems. First and second lens frames respectively correspond to, and respectively retain, the first and second lens compartments. The first and second lens compartments are independent structures from the first and second lens frames to allow the first and second lens compartments to be removed from, and inserted into, the respectively corresponding first and second lens frames. The present invention also relates to a method of assembling the lens apparatus.

Abstract: A thermal imaging device (10) provides for its use with a variety of accessory telescopic lenses (12). Each of the accessory telescopic lenses (12) and the thermal imaging device (10) include cooperating physical features allowing the lenses (12) to be mated with the device (10) in a single relative position. Each lens (12) also carries a uniquely positioned magnet (176), and the thermal imaging device (10) includes a plurality of magnetically-responsive sensors (178) responding to the magnets (176) of the various lenses (12) to identify which (if any) of the accessory lens (12) is installed on the device (10). Some of the accessory lenses (12) also include a variable-power feature. These variable-power lenses (12) have an additional magnet (182) moving between an effective position and an ineffective position in response to a user-selected power setting for the lens (12).

Abstract: In the optical coupling system where the space between projection lens and CRT is connected with a liquid, this invention aims to offer a projection lens unit wherein the angle of CRT relative to the optical axis of projection lens (tilt angle) may be changed by quite a simple operation; thereby the CRT tilt angle can be reset to an optimum when the angle of projection oblique to a screen shifts. Namely, a first housing and a second housing in which an optical coupling liquid is contained and sealed are coupled together with an watertight structure like a piston and cylinder and fixed, and a ring cam for regulating the relative space and tilt is held between the two housings; by fastening the two housings together with bolts, etc. the two housings can be set at a desired relative positioning.

Abstract: A lens supporting assembly for use in a photoprinting machine can position a varifocal lens with high accuracy over a long period time. A lens plate carrying a varifocal lens has bent portions along both side edges and is formed with a plurality of positioning holes. A lens support table has positioning pins adapted to be engaged in the positioning holes. It is further provided with first magnets for attracting the bottom of the lens plate and a second magnet for attracting one of the bent portions. By lowering the lens plate onto the lens support table, the positioning pins engage in the positioning holes, so that the varifocal lens can be set in position with high accuracy. In this state, the first magnets attract the bottom of the lens plate, while the second magnet attracts the bent portion, so that the varifocal lens can be stably held in position.

Abstract: A lens mount for a TV camera for mounting a lens having a bayonet ring on its rear face and a cylindrical projection which is smaller in diameter than the bayonet ring and extends rearward coaxially with the optical axis of the lens is provided with a camera-side bayonet ring which is movable between an engagement position where the camera-side bayonet ring is engaged with the lens side bayonet ring to hold the lens on the camera and a disengagement position where the bayonet rings are disengaged from each other to permit removal of the lens from the camera.

Abstract: A lens having radially extending members provided with convex engaging projections is positioned and secured in a lens supporting sleeve having L-shaped openings with recessed engaging grooves. The radially extending members are positioned with respect to a reference surface of the sleeve, and subsequently elastically deform circumferentially extending clamping arms of the sleeve as they are rotated into clamping portions of the L-shaped openings. The convex engaging projections are then snapped into the engaging grooves, holding the lens in position.

Abstract: A projection type exposure apparatus is provided for illuminating a mask formed with a pattern with an illumination light having a predetermined wavelength area and forming an image of the pattern on a substrate through a projection optical system. This apparatus comprises a projection optical system incorporating a plurality of lens barrel units each housing one or more optical elements. Each lens barrel unit is so mounted in the projection optical system as to be attachable thereto and detachable therefrom.

Abstract: A lens assembly including a printed circuit board having a longitudinal series of light emitting diodes, a casing mounted on the printed circuit board and covered over the light emitting diodes and having a glass cover, and a lens having a bottom side mounted on the glass cover, a plane top surface, and a sand finished, peripheral surface which confines the light of the LEDs to the plane top surface of the lens.

Abstract: A variable focus adapter is disclosed that comprises the combination of a ns and an aperture provided by a plate all lodged in a housing that is placed so that the lens is in proximity with each objective lens of a binocular arrangement to change the focal range from greater than 20 ft. to seven (7) ft. with a depth of field spanning from 5 to 15 ft.

Abstract: The invention relates to a device for inserting optical and mechanical components into mounting sleeves. The components are introduced upward from below into the mounting sleeve through a lead-through opening having movable locking elements. Although the locking elements allow the insertion of the components, they prevent the locking elements from leaving the mounting sleeve. The mounting sleeve is thus successively filled with insert parts. This type of insertion to a large extent counteracts the generation of dirt particles, in particular between the insert parts, and is outstandingly suitable for automation.

Abstract: A lens barrel includes a fixed tube, a moving tube arranged to move in the direction of an optical axis over the outer circumference of the fixed tube and to have a cutout part, and a band-like circuit board disposed around the optical axis on the outside of the fixed tube and having a part located inside the moving tube within an area corresponding to the cutout part and a part located outside the moving tube within an area other than the area corresponding to the cutout part.

Abstract: A lens barrel comprises a barrel body, inside and outside fitting members disposed within the barrel body at a predetermined interval in a direction along an axis thereof and each formed with a female screw, an inside lens holding frame having a male screw screwed into the female screw of the inside fitting member and an outside lens holding frame having a male screw screwed into the female screw of the outside fitting member. An external diameter of the male screw of the inside lens holding frame is larger than an internal diameter of the female screw of the outside fitting member. The male screw of the inside lens holding frame is segmented into a plurality of portions by a plurality of notches having an internal diameter smaller than the internal diameter of the female screw. The lens barrel also comprises a plurality of recesses formed in the outside fitting member and admitting passages of the plurality of segmented male screw portions of the inside lens holding frame.

Abstract: An apparatus and method for aligning the optical elements of a microscope are disclosed wherein a fixture is provided for locating and mounting a plurality of mirrors for reflecting an object image along an optical path to an adjacent eyepiece connected to the fixture by an eyepiece holder. The eyepiece holder includes an outer sleeve attachable to the fixture, an inner sleeve transversely movable within the outer sleeve for slidably receiving the eyepiece, and positioning means comprising a plurality of angularly spaced screws extending through the outer sleeve for engaging the inner sleeve, whereby the eyepiece may be aligned on the optical path by selectively adjusting the screws.

Abstract: The present invention is directed to an apparatus for aligning optical elements and a method used to test aspheric components using a conventional interferometer. The apparatus comprises an optical mount having a base and a mount plate used for adjustably mounting an optical element. The mount plate is adjustable relative to the base and includes an assembly surface and several side surfaces. The base is attachable to a bench, table, rail, or the like. An optical element, such as a pre-aligned alignment CGH, is positioned within a first frame, which in turn is releasably coupled to the mount plate. The interferometer generates a spherical test beam which is diffracted by the reflective alignment CGH to create an interferogram. The mount plate is adjusted relative to the base to diffract the test beam onto itself, thus producing null interference fringes.

Abstract: An optical element support for supporting optical elements adjacent to a lens of a camera. The support comprises an optical element holder assembly which is mountable to the camera lens housing. The holder assembly includes at least one stack of discrete holder members configured so that adjacent ones of the holder members together define grooves therebetween to hold a desired selection, by number and dimension, of optical elements. The holder members are removably connectable and further configured such that a rearrangement of the holder members in the stack permits variation in the number and/or width of the grooves and the accommodation in the grooves of optical elements of different number and/or thickness.

Abstract: An optical element holder holds an optical element while minimizing the profile irregularity of the optical element. The optical element holder is provided with three holding portions which abut and engage the peripheral side surface of the optical element at first, second and third positions, respectively. One of the holding portions is movable and can be moved to and away from the peripheral side surface of the optical element, thereby securing the optical element in the optical element holder and releasing the optical element from the optical element holder, respectively.

Abstract: A connector including a first connector cover having a first engaging portion, a second connector cover having a second engaging portion for engaging with the first engaging portion and adapted to be mounted in a superposed manner on the first connector cover, plural contact members positioned between the first and second connector covers and having plural movable contact pins biased as to protrude from the external face of the first connector cover, and a conductive pattern bearing member positioned partly between the first and second connector covers and provided with conductive patterns on a face contacting the movable contact pins. The first connector cover is further provided with a third engaging portion, while the conductive pattern bearing member is provided with a fourth engaging portion for positioning the conductive pattern bearing member relative to the first connector cover by engagement with the third engaging portion.

Abstract: A binocular includes an eye-piece tube, a first lens system associated with the eye-piece tube for providing a base magnification as seen through the eye-piece tube, and an eye-piece module having a second lens system therein which is interchangeably installed in the eye piece tube for changing the position of the first lens system to a position of a preset increase in magnification.

Abstract: A lens accessory attaching mechanism is provided to attach a lens accessory to a lens barrel. The lens attaching mechanism has four pairs of first and second rollers attached to the proximal end portion of the lens accessory into which the distal end of the lens barrel is inserted. The first and second rollers are equiangularly spaced in the circumferential direction of the lens accessory and are movable in a radial direction thereof. A ring spring arranged around all of the first and second rollers urges the rollers radially inwardly. An outer flange portion formed on the outer periphery of the lens barrel abuts the first and second rollers to restrict the movement of the lens accessory in the axial direction of the lens barrel.

Abstract: An optical holder for mounting and orienting a lens or lens subassembly by se of a removable retaining lens within a mount ring. Two adjustment set screws and a pressure pin mechanism hold the retaining lens. A constant pressure is applied against the set screws which is releasable. The retaining lens ring can then be removed and replaced without loss of alignment.

Abstract: A coupling device and associated method for coupling an unassociated afocal optical assembly to a night vision apparatus in order to alter the optical power normally associated with the night vision. The coupling device includes two separate adapter rings that threadably connect to each other. The first adaptor ring is sized and shaped to threadably engage the night vision apparatus proximate the objective lens of the night vision apparatus. The second adaptor ring is sized and shaped to screw onto the output end of the afocal optical assembly. Accordingly, when the first adaptor ring is joined to the second adaptor ring, the output end of the afocal optical assembly is optically aligned with the objective lens of the night vision apparatus. Consequently, the afocal optical assembly enhances the optical power associated with the night vision apparatus.

Abstract: Compact and lightweight portable collimator for adjusting an optical system of a video camera is disclosed, the collimator comprises a chart piece holding a chart pattern for producing an image of the chart pattern placed at a focal point of a convex lens which converts a light from the chart pattern into a beam of parallel light and projecting the beam toward the video camera, a cylinder for housing the chart piece and the convex lens, and coupling device rotatably coupling the cylinder to a lens barrel of the video camera so that an orientation of the chart pattern can be changed and the optical system of the video camera can be adjusted to a distance of infinity. The chart piece may be made replaceable so as to place the chart pattern within a focal length of the convex lens to optically synthesize an object placed closer than the infinite distance with respect to an objective lens of the video camera.

Abstract: An ophthalmic lens holder for holding lenses in a tinting bath has an upright support with oppositely directed base channels and spring loaded pivoted clamping arms over the base channels. Lenses are held side by side between the clamping arms and the base channels. The holder is designed to facilitate insertion and viewing of the lenses.

Abstract: A mounting seat for an optical element is decoupled from a surrounding annulus that fixes the mount in place in an optical system. The annulus can be one of a plurality of annuli that are interconnected to surround and enclose a coaxial array of optical elements. The decoupling is accomplished by three flexible fingers extending inward from the annulus to a seat for the optical element, which can be mounted either directly on the flexible fingers or on a concentric seating ring supported by the fingers. The flexible elements can be formed integrally with an annulus by cutting slots in its inner perimeter. The flexible elements are structured relative to the lens elements they support so that natural frequencies of vibration of the lens elements are higher than the frequencies of external vibration.

Abstract: A lens centering apparatus of a lens barrel having therein a lens supporting frame includes male threads provided on an outer periphery of the lens supporting frame, and female thread sets provided on the lens barrel and having different centers. The female thread sets can be selectively engaged by the male threads of the lens supporting frame.

Abstract: A mechanical coupler for connection to the eyepiece of an optical device. The coupler includes a body with an axially extending cylindrical wall that forms a socket with a spanning portion of the body. The cylindrical wall and body center and axially align the coupler and the eyepiece. A C-shaped clamping member has a central portion that is affixed to the wall and essentially tangentially extending free end portions that produce a side opening structure. When an eyepiece is inserted from the side, it wedges the free ends of the clamping member axially thereby producing internal restoring forces in the clamping member. When the eyepiece is seated in the socket, the free ends return toward a relaxed position and produce a clamping force that affixes the coupler axially to the eyepiece while permitting relative rotation between them.

Abstract: A supporting member made of elastomer materials is inserted with pressure into a chassis, and a support portion projects inside the chassis. The supporting member supports the ends of the convex lens and concave lens.

Abstract: An object lens holder for holding an object lens for converging a laser light radiated from a laser light source on a signal recording surface of an optical recording medium includes a bobbin part formed by abutting and connecting first and second bobbin halves which are counterparts to each other, a holder part formed by abutting and connecting first and second holder halves which are counterparts to each other, which holder part is used as a mounting supporting part to a supporting base plate, first and second resilient, deflecting members arranged in parallel to each other for interconnecting the first bobbin half and the first holder half, and third and fourth resilient deflecting members arranged in parallel to each other and to the first and second resilient, deflecting members for interconnecting the second bobbin half and the second holder half.

Abstract: A low vision lens for attachment to the front surface of an ophthalmic lens by an adhesive ring coupling carried by the lens, a method for making such a lens assembly, and a method for attaching such lens to the front surface of ophthalmic lens is described.

Abstract: This device is characterized in that it includes removable indexing and locking devices of the light intensifier assembly on the stationary imager operating in combination with opening and closing control devices of a light shutter of said stationary imager in such a way that the locking or unlocking of the intensifier assembly simultaneously causes the opening or closing of shutter, and that all the operations can be carried out with one hand only and blindly.

Abstract: Guide bars supporting a plurality of lens frames are inserted through the opening formed in a side of a lens housing. The direction of insertion is perpendicular to the optical axis of the lenses supported by the lens frames. The guide bars and lens frames are then arranged at predetermined positions in the lens housing. Then, a cam tube is inserted through the opening in the direction perpendicular to the optical axis. Cam pins formed on the lens frames are then coupled to cam grooves formed in the cam tube.

Abstract: There is disclosed an optical unit which is primarily intended to provide visual references for measuring machines such as coordinate measuring machines, milling machines, EDM machines, tape and computer controlled drilling machines, etc. The optical unit has a motor driven zoom lens within a lens housing, and an optical coupling for a video camera. The zoom lens assembly of this invention is a modification of that shown in U.S. Pat. No. 4,884,878 to include a stepper drive motor and a rotational position encoder which provides the necessary lens information to determine the power of magnification of the lens at any instant position. The preferred encoder includes a disc mounted on the barrel of the zoom lens which has a plurality of slots about its periphery at equal angular increments, and a photo-optical sensor which counts light pulses and generates a pulsed electrical signal as the disc rotates beside the sensor.

Abstract: A lens loading apparatus for loading a lens held by a holding member into a lens loading unit disposed in the center of a support plate which extends substantially in a horizontal direction. The lens loading apparatus has a first reference surface formed in the upper surface of the support plate along a lens insertion direction and used for placing the holding member thereon. A second reference surface is formed on the support plate along the lens insertion direction and against which one end surface of the holding member, which extends along the lens insertion direction, abuts. The holding member, which is inserted from a horizontally-extending one end, is guided along the second reference surface by a first pressing member. Further, the holding member is guided along the first reference surface by a second pressing member, thereby making it possible to stably position the lens in a predetermined place.

Abstract: A lens barrel attachment including an attachment ring and a handle in which a click pin is housed. The attachment ring is rotatably fitted on a large-sized lens barrel. The handle is threadingly fitted in a handle hole formed in the attachment ring and extending in a radial direction thereof. The click pin is provided in an accommodation hole formed in the handle and urged by a spring to be engaged with engaging recesses formed on an outer surface of the lens barrel. The handle has a contact portion at the tip portion thereof. This contact portion is brought into frictional contact with the lens barrel to thereby fix the lens barrel to the attachment ring.

Abstract: A protection device for a lens used in a scanning apparatus for imaging data on photographic film, comprises a plate and having a finger gripping portion, a member slidably retained in the plate, a glass piece removably carried by the member, and a biasing member operatively associated with the member for selectively permitting secure holding of the glass piece on the member and easy removal of the glass piece from the member. The plate is provided with a biasing device for securely retaining the member in a desired location such that the glass piece is in a predetermined lens protecting position. A switch is associated with the plate such that the switch is moved to an open position upon movement of the member away from the plate. The biasing member is a pivotally mounted spring configured to hold the glass piece in a desired location on the member and has V-shaped portions to engage portions of the member for positive locking of the spring in the member.

Abstract: A conversion arrangement for mounting optical units on a camera such as a film or television camera has a generally cylindrical mounting body (12, 14) for attachments to the camera body, a generally cylindrical carrier (B) for attachment to the optical unit, the carrier being coaxially coupled to the mounting body for axle movement relative to the mounting body, and a focusing ring (22) which is co-axial with and coupled to both the mounting body (12, 14) and the carrier (B). The focusing ring is rotatable relative to the mounting body and carrier to move the carrier axially off the mounting body to focus the optical unit. Backlash during focusing is reduced to negligible proportions by use of a screw-thread arrangement in which a screw-thread is formed on a radially inner wall of the focusing ring by means of a wire coil (44), the pitch of the wire coil being set by end members (46) and gapped rings (48) acting as spacers between the turns of the wire coil.

Abstract: An auxiliary lens attachment, installed a prescription or colored enhancement lens, is mounted onto an end of a rifle scope. The auxiliary lens attachment includes an adaptor having a lens receiving portion at a first end, a lens securing portion in a middle and a rifle scope mounting portion at a second end. A distance adjusting member is positioned on the securing portion of the adaptor to adjust the distance between the securing portion and the mounting portion.

Abstract: An element, such as a lens, is mounted on an element holder, such as a lens holder, so as to be constrained with a clearance-free, exact centering fit. The element has three radial faces spaced 120.degree. apart with respect to the center of the element, and the element holder has three abutments spaced 120.degree. apart with respect to a center point about which the abutments are distributed. Upon seating the element in the element holder with the radial faces and abutments in engagement, the element is constrained with the center points of the element and element holder in alignment. The radial faces and abutments are held in engagement by a retainer which also holds the element on the element holder. In accordance with one embodiment of the invention, the element is a plastic lens, and the element holder is a lens barrel, the lens being retained with clearance within the lens barrel by a retaining ring.

Abstract: A lens frame consists of a lens barrel with a built-in projection lens and a support member in which the lens barrel is inserted and supported. The lens barrel has on its outer surface a pair of axially spaced projections as a slide member. The support member has on its inner surface projected guide strips that extend inclined with respect to a plane perpendicular to the axis of the support member. The support member also has axially extending ribs on the inner surface that tightly engage with the outer surface of the lens barrel as the latter is inserted into the former, in order to keep their axes aligned. With the lens barrel inserted and the projected guide strip received between the paired projections, the lens barrel is rotated and the paired projections are guided along the inclined projected guide strip, causing the lens barrel to move forward or backward in the axial direction. In this way, the focus adjustment can easily be made.

Abstract: A divergent lens (4) perforated in its center by a hole (5) of small diameter is placed opposite the aperture (12) of a laser beam type marker (10) in order to pick up the laser beam comprising substantially parallel rays (13) from the marker, the lens (4) deflecting the laser rays which reach it round the central hole (9) so as to produce a divergent beam (14) whereas the rays which reach the central hole (4) pass through it without being deflected so as to form a fine pencil of light (15) of higher intensity serving to mark a target. The divergent lens (4) is, for example, mounted in a aperture (3) provided in the head of a body (2) intended to be slid on and to cover the head (11) of a laser beam type marker (10). The divergent lens (4) can also be mounted in the aperture (12) provided in the head (11) of a laser beam type marker (10 ).

Abstract: A telescope housing has a removable finger accommodating ring secured thereto. The ring is coupled to the housing by a post having left and right flanges with upstanding distal ends opposedly projecting from one end of the post to be inserted into an aperture located in a latch on the ring. In this manner, various telescope assemblies of different magnification can be accommodated by the use of the removable ring which also enables convenient storage.

Abstract: A compound aspherical lens comprising: a hard lens; a soft lens laminated to the hard lens in a direction of the optical axis; and a lens supporting surface formed around the effective diameter of the hard lens and exposed in the direction of the optical axis when the soft lens is laminated to the hard lens.

Abstract: An optical mounting apparatus comprises an upper support assembly and a lower post assembly. The upper support assembly includes a stageplate mounted on a backing plate by a three point suspension mechanism. By locating an optical element mounting region at the corner of a rectangle defined by the three suspension points, a datum point within the region can be rotationally adjusted without simultaneous translational adjustment by manipulating only two of the three suspension points. The baseplate is mounted on a support rod which is slidably received in a casing. A lever arm having a surface which engages the support rod can be moved relative to the casing for selectively locking the rod in place.