WO2007031993A2

WO2007031993A2 - Device for maintaining line of sight for intruments by using tilted and adjustable lenses

Info

Publication number: WO2007031993A2
Application number: PCT/IL2006/001053
Authority: WO
Inventors: Daniel Farb
Original assignee: Daniel Farb
Priority date: 2005-09-13
Filing date: 2006-09-10
Publication date: 2007-03-22
Also published as: WO2007031993A3

Abstract

The present invention describes means for providing line of sight and/or magnification from a lens to a working area without having to hold or use separate devices or arms of the instrument in order to achieve focus on the working area. Additionally, several mechanical solutions are presented to the problem of maintaining the line of sight of a lens on the working area as it is moved. A basic concept of the inventions is the use of tilting the magnifying lens at different angles at different distances to achieve an automatic line of sight. The invention has application to many surgical, consumer, and industrial devices.

Description

DEVICE FOR MAINTAINING LINE OF SIGHT FOR INSTRUMENTS BY USING TILTED AND ADJUSTABLE LENSES

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to a lens attached to instruments, and, more particularly, to methods of visualizing work performed by the instruments.

The ability to see what one is doing with instruments, particularly finer ones, is an old problem, which applies to medical equipment, specialty equipment in areas such as car repair, consumer items such as tweezers for removing splinters, and fine manufacturing, assembly, and construction. The problem involves magnification (enlarging the image), accommodation (the ability of the eye to focus on the image), and refraction (the ability of the eye to see at various distances with a focal point that differs among far-sighted and near-sighted people). The accommodation problem is particularly distressing for older people, particularly past the age of 40, when they usually require additional lenses to address the problem of presbyopia (the inability to bring near focus to bear on an object due to loss of accommodative power).

Prior solutions have been directed at the magnification problem alone and require the user to move either one's own head or arm while holding a separate device such as a magnifying glass in order to maintain focus. Some solutions have included magnifying or telescopic lenses mounted on headpieces or attached to glasses, but these tend to be either inconvenient or bulky for much work and are used mostly in certain types of surgery. Surgical microscopes are a good solution, but not all instruments are medical and not all situations of fine instrument use are appropriate for an operating room. Other solutions have involved fixing a magnifying glass to the instrument itself. Prior art using this solution has been of two types, and both have disadvantages: Lenses attached to a fixed location on the instrument are difficult for people with different refractive states (in other words, different eye glass prescriptions) to use uniformly well. Lenses attached to a side arm require separate manipulation of the side arm while using the instrument, and usually do not hold the focus on a particular spot as they are moved. (The angle of focus moves from one spot to another as the side arm is moved.)

An additional problem for presbyopic individuals attempting to use certain devices wherein an upward view is required is that the bifocal addition to their glasses is always placed inferior to the distance portion of the lens, and they cannot have clear vision at near to moderate distance for using instruments that they have to raise above their heads. Another example would be a car mechanic who has trouble using tools when looking at his upper field of vision.

Examples of prior art without solutions to these issues follow: US Patent 6,612,262 is an animal tattoo device. A magnifying glass is mounted onto a separate, static arm of a tweezer-like device. US Patent 6,598,311 uses a fixed magnifying glass to read a tape measure. US Patent 6,083,177 is a static magnifying lens positioned on a biopsy sheath that is circular and surrounds the sheath. US Patent 5,358,297 is a tweezers with hinged magnifying glass attached to a separate arm. US Patents 5,263,754 and 4,836,596 similarly have attached arms.

There is thus a widely recognized need for adequate solutions for lenses that accompany instruments (which word, for the purpose of this patent, is used interchangeably with "tools," "devices," and similar terms), and it would be highly advantageous to have a lens mounted onto the existing arm of an instrument that enables the focus to be maintained on the area of work, usually the tip of the instrument, for eyes with different refractive powers and accommodative abilities, and which enables minimal if any handling of a separate attachment while doing the work. In addition, it would be advantageous if the field of magnified vision could be increased or decreased by to and fro movement of the lens while maintaining the working area in the center of the lens automatically.

It is not a mere problem of magnification; the movement back and forth of a lens that is moving in a line parallel to the line of a linear instrument has to maintain a focus on the end of the instrument even though the line of sight is at a different angle at different distances from the end of the instrument.

Multifocal lenses are a recent invention and are implanted inside the eye after cataract removal in order to provide one lens that enables focus at different focal lengths. They have not heretofore been applied to the problem of obtaining focus on a particular point by being attached to an instrument, or by being used in combination with a second lens in order to magnify an area of interest.

An example of the usefulness of the invention would be a forceps for either home or surgical use that required no additional instrumentation or visual aids in order to obtain a magnified, focused view of the end of the forceps as it was used to remove a splinter or hold a piece of tissue. As a different field of vision is required around the working area, the lens could be moved back and forth without disturbing the line of sight.

Surgeons need minor surgical instruments that provide their own magnification, and such instruments are not available on the market.

The current invention proposes innovative mechanisms of focusing on an area of interest for which an instrument is used.

The invention differs in a significant way from prior art, which has not addressed the concepts of a movable lens and of adjustment of the angle of the lens while moving the lens. The problem affects users in many different situations in a significant manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic representation of a groove on an instrument.

FIG. 2 is a schematic representation of clips on the outer surface of an instrument.

FIG. 3 is a schematic representation of a groove with protrusions.

FIG. 4 represents different angles of the lens attached with a hinge to a lens holder to a leg at different distances in order to maintain focus on the working area.

FIG. 5 is a schematic representation of the principle of different angles of the lens attached without a hinge to a holder to a leg at different distances in order to maintain focus on the object of interest.

FIG. 6 is a schematic representation of two lenses at an angle.

FIG. 7 is a schematic representation of a series of equivalently-shaped nubbins or indentations at different angles.

FIG. 8 is a schematic representation of a gear attached to a leg.

FIG. 9 is a superior view of an instrument that shows how the lens would also tilt side to side.

FIG. 10 is a picture of a nub/depression moving system.

FIG. 11 is a picture of a groove system at the base of the sliding lens system.

FIG. 12 is a picture of a lens holder placed on a forceps.

FIG. 13 is a picture of a stepper mechanism. FIG. 14 is a picture of the parts of a pin-tilt mechanism.

FIG. 15 shows a system of pressure and limited ribs holding the magnifying device.

FIG. 16 is a lens holder that twists from side to side.

FIG. 17 is a lens holder with grooves.

FIG. 18 is the inside of a lens holder with grooves.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Definitions: A lens system refers to the use of at least one lens in the current invention, such that a second lens can be placed in a stationary position, or attached to the same base, leg, and lens holder, or placed on a second base, leg, and lens holder. This lens system may be attached to an instrument that clips onto another instrument (a tool), or attached to the tool directly. A lens holder is used interchangeably with extender, because the lens may be held by a holder that connects directly to the leg or by a holder that moves in relation to the leg. The term leg is used to refer to the shaft that arises from the base of the lens system. That term is used to distinguish it from the common description of instruments as having arms. The term working area may refer to the tip of an instrument, or the area that the tip of the instrument needs to work on. An instrument may refer either to a tool or device such as a tweezers or wrench, or to a portable line of sight attachment that attaches to or clips on to another instrument. Since the leg, lens holder, and lens are attached to the base, movement of the base or the lens system refers to movement relative to the instrument to which the base is non-fixedly attached. That group is referred to as a first instrument. A second instrument is the part — usually but not necessarily the functional instrument such as a tweezers — to which the first instrument with the adjustable lens is attached. In cases apparent by context, instrument refers to the combination of the^' instrument that clips on to the tool or to the tool itself. The central line of sight refers to the imaginary line that passes through the center of a lens perpendicular to the plane of the lens. Said imaginary line intersects the working area.

The present invention is of a lens which can be attached or built into the arm of an instrument in any of several ways to achieve the purpose of magnifying a particular area without the use of extra side arms and other instruments and magnifying glasses, and which maintains a central line of sight on the working area at different distances. Specifically, the present invention can be used to perform many household, medical, mechanical, and industrial tasks in a more precise manner using any of several possible configurations of the principle just noted.

The principles and operation of an attached lens according to the present invention may be better understood with reference to the drawings and the accompanying description.

Referring now to the drawings, Figure 1 illustrates the shaft of an instrument (Part number 1), which for illustrative purposes is an outline of a tweezers, but which could be any device. A groove or protrusion (Part number 2) is built into the instrument, thereby allowing the attachment of a lens system, which may be moved to and from an object. As mentioned in the definitions, the lens may attach to a separate device attached to the tweezers, the instrument.

Another possible configuration is shown in Figure 2, in which a lens system may be attached to an instrument arm by means of an adjustable clip connecting the first to the second instrument, or by means of protrusions and depressions on the outside of the instrument that allow a lens system to be attached. This clip could be detachable and particularly suited for sterilization in medical devices.

Figures 1 and 2 show the construction of the instrument [or attachment to the instrument as in part (3)] in such a manner that the lens may be moved along the shaft of the instrument.

Figure 12 is a picture of a lens holder placed on a forceps. It illustrates how the holding means in Figures 1 and 2 might result in a lens being held. The basic parts of a lens system are a base with a holder or slider, a lens, an optional extender of the lens as part of a lens holder, and a leg that holds the lens holder and is attached on the other side to the base. The leg may be fixedly part of the lens holder in some embodiments.

Figure 14 is a picture of the parts of a pin-tilt mechanism. This invention allows adjustment but not an automatic line of sight. Part (40) is a slider-holder integrated into the part referred to as the base. Part (42) is a pin-tilt or other means to tilt the lens in a fixed plane in the line of sight of the viewer. Part (44) is a groove or other structure that permits the attachment of the base (46). The base is then connected to a leg (48), which then holds the lens (49). The lens may optionally have an extender called a lens holder, or the lens may be fixedly attached to the leg. The lens may optionally pivot from side to side. Figure 15 illustrates a system of pressure and limited ribs holding the magnifying device. Part (52) is the slider — apart of the base—of the lens system. (53) is the base of the lens portion. (54) is the leg attaching the base to the lens holder. (55) is the lens holder. (56) is the lens. (57) is the pin tilt. The figure also shows how pressure and limiter ribs on the side keep the base in place on the slider.

Figure 16 is a lens holder that pivots from side to side. It shows the basic parts of the embodiments of the inventions. Part (60) is a lens system possessing a holder/slider. It optionally slides back and forth on the instrument it is attached to. Part (66) is a base in the form of a tilt shaft. Part (64) is the leg attached to the .base and attached to a lens holder. Part (62) is the lens. The lens system with the slider may also be attached to the slim side of an instrument. It is merely illustrated here on the thick side of a forceps.

Figure 3 illustrates one of many ways in which the attachment for the base holding the lens may be created. A series of protrusions and depressions will allow a base to lock into place along a line. The groove, instrument, or clip may have regularly spaced nubs (Parts number 4) for holding the lens system in place. Not shown from this angle is the possibility that the protrusions have slightly different orientations to lock in the upper part of the instrument with the lens at different angles in order to maintain focus on the working area.

Yet another configuration not shown allows the upper section of the instrument to push against the sides of the groove, attachment, or instrument in such a way that it may be moved into different positions. This can be accomplished with or without a spring.

Figure 4 illustrates another embodiment of the invention. It is a side view of an instrument with the work area of the instrument at the left. At different distances from the work area, the lens (Part number 6) is affixed to a leg (Part number 5), which is attached to the base at a different angle. These different angles are constructed so that the point of focus of the lens at all times remains upon the work area of the instrument.

Figure 5 illustrates a different version of the invention. The difference between Figures 4 and 5 is that Figure 4 shows a means for tilting the lens alone, whereas Figure 5 shows a leg attached to the lens (directly or indirectly), which tilts as a unit (Part number 7) at different distances from the tip of the instrument. Figure 6 is a schematic representation of the principle of using a plurality of lenses to adjust the line of sight on the working area, in which at least one lens is movable and maintains the necessary angle to maintain focus on the area of interest. The same picture can represent the different locations of a single lens, whether of one power or multifocal, mounted in such a way that it maintains focus on an instrument tip.

Figure 6 shows another possible embodiment of the invention. A groove (or plurality of protrusions or depressions) can be set at an angle (Part number 9) on the base or clip attached to the instrument, with the portion containing the lens capable of attaining different positions at different distances from the tip with the line of sight remaining on the tip of the instrument on the left. The line represents a device on an instrument arm or clip which is angled in order to provide a direction of movement for the base with the lens.

Figure 6 is also an illustration of how two lenses (Part number 8 is one of them), whether one is multifocal or not, could work together to magnify the tip of the instrument.

Figure 7 is a schematic representation of how a series of equivalently-shaped depressions or protrusions can be used to affix a corresponding depression or protrusion on the instrument at different angles.

Figure 7 illustrates one way of designing the manner in which the lens may extend in a parallel line to the shaft of the instrument and may automatically assume the correct angle to remain focused on the tip of the instrument on the left. Depressions or protrusions of a fixed shape on the base of the lens system that match a fixed shape on the shaft or clip of the instrument (Part number 10) enable the positioning of the lens at different angles at different distances from the tip of the instrument. In one embodiment, the base may have a place for squeezing a part that causes parts of the fixture to protrude and retract so that it can be moved to match the part connected to the instrument shaft. Figure 18 will illustrate that in more detail.

Figure 8 is a schematic representation of how a series of ridges (11) on the instrument would interlock with a base containing gears (12) and then connect to the leg or lens holder to alter the angle at which the attached lens points. Thereby the lens automatically maintains a line of sight on a working area. In this embodiment, the gears may automatically turn the lens an amount that maintains focus on the tip of the instrument. In another embodiment, a multifocal lens may be fixed in one location but angled towards the tip of the instrument.

In Figure 9, another embodiment, the lens may move sideways in addition to up and down in order to maintain focus on the end of a device. An example would be a right-angle forceps (Part number 13) of the type shown in Figure 9. An internal gear mechanism can maintain the focus on a point while it is moved.

Figure 10 is a picture of a protrusion/depression moving system. Part (18) is the lens. Part (17) is the leg that connects to Part (16), the base. (There is of course a lens holder that attaches or surrounds the lens and attaches it to the leg.) The base is responsible for moving the lens system forwards and backwards in a groove (15) on the instrument. The groove is part of the instrument or an attachment to the instrument. Parts (10) and (14) represent an interlocking array of protrusions and depressions that lock in the base at different positions at different angles.

Figure 11 is a picture of a groove system at the base of a sliding lens system. It shows one concept of automatic maintenance of line of sight for the tip of a straight instrument. There are 2 separated sliders, (19) and (22), surrounding the instrument arm (21), which are linked by an arc-shaped flexible bar (24). (22) is part of the lens system; (19) is part of the instrument. Extensions on parts (19) and (22) help hold the sliders in place. The bar in this illustration contains 6 grooves (but the invention can be more or less than 6). On top of the bar is a leg attached to a lens.

Here is one mechanism of action: Set the position of slider (19) and fixate. In the Zero Tilt Position, the lens' central line of sight is directed to the tip of the instrument. Moving slider (22) toward slider (19) will cause the groove on the arced bar of slider (22) to climb until it engages with the round edge (26) of slider (19). This engagement will affect the angle of lens tilt and keep the lens focused on the instrument tip. Part (25) prevents disengagement from the other side. Each groove will change the angle by x degrees from the zero position. That change of degrees in the angle of the lens is coordinated with the distance removed from the working area. Moving the sliders towards each other will increase the tilt position of the lens as the lens changes distance from the tip. The tilting points the viewer line of sight to the tip of the instrument. Moving the sliders apart will decrease the angle of tilt but keep the line of sight. This concept produces full and automatic adaptation of the user and the lens to the tweezer tip. A different and smaller shape can replace the functionality of slider (19). This shape can be snapped on, screwed, or glued to the tweezers. A built-in shape is an option for an instrument dedicated to a certain function.

Figure 13 is a picture of a stepper mechanism that is somewhat the reverse of the previous automatic line of sight concept. There is one slider (32) on the lens system which is linked by an arc-shaped flexible bar to the base of the lens system. The bar in this illustration has one nipple shape (30) but all that is significant is that it should have a means to interact with the grooves. On top of the bar is the leg, part (38). On the instrument (36) there is a large groove with "rest points" (34) facing the stepper (30).

Here is the mechanism of action: In the Zero Tilt Position the lens is directed to the tip of the instrument. Moving the lens system's slider (32) upward on the grooves will cause the arced bar of slider (32) to climb until it engages with one of the rest points (34). TMs engagement will affect the angle of lens tilt and keep the lens focused on the instrument tip. Each rest point in the groove will change the angle by x degrees from the zero position. Moving the slide backwards will increase the tilt position of the lens. Moving the slide forward will decrease the angle of tilt but keep the line of sight. This concept produces full and automatic adaptation of the user and the lens to the tweezers tip.

The following describes another automatic mechanism to keep the line of sight of the viewer on the instrument tip. Figure 17 is a lens system with grooves (70) on the body of the instrument (Figure 18, 75). Figure 18 is the inside of a lens system with grooves. There is one slider (Figure 17, 72; Figure 18, 76) on the base which has a "tooth" positioned into grooves along the side of the instrument. The slider of the base is attached to the instrument by a "U" shape and the knob (Figure 18, 77) with a spring (Figure 18, 78). Pressure applied by the user on the knob releases the slider from one position and allows the slider to move to the next position. On top of the slider of the base, the leg (Figure 17, 72) is attached to the lens holder.

Mechanism of action: In the Zero Tilt Position the lens is directed to the tip of the instrument. Moving the base's slider (Figure 17, 72; Figure 18, 76) forward will end by engagement into an angled position on the following rest point. This engagement will affect the angle of lens tilt and keep the lens focused on the instrument's tip. Each rest point will change the angle by x degrees from the zero position. Moving the slide backwards will decrease the tilt position of the lens. Moving the slide forward will increase the angle of tilt but keep the line of sight. This concept produces full and automatic adaptation of the user and the lens to the instrument tip.

While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made. More than one lens may be used on each device; at least one lens would be mobile. The extender may be replaceable and different lens sizes can be used.

SUMMARY OF THE INVENTION

The present invention successfully addresses the shortcomings of the presently known configurations by providing a mechanism of assuring steady, magnified focus on the area of interest to the person working with an instrument and overcoming the difficulties of poor accommodation and the need for other instruments and arms to provide magnification.

Introduced for the first time is a device for maintaining a central line of sight on a working area, comprising a. a lens system, comprising at least one lens with a focal point at the working area of an instrument, a lens holder holding the lens system, a leg attached to the lens holder on a first side of the leg, and a base attached to the leg on a second side of the leg, b. an instrument to which the base is attached, c. means for centering the central line of sight of the lens on a working area as the base changes distance from the working area.

In one embodiment, at least one lens of the lens system is a multifocal lens.

In one embodiment, the lens holder has a means for rotating the lens.

In one embodiment, the base is attached non-fixedly to the instrument.

In one embodiment, the base is attached to an arm of the instrument.

In one embodiment, the invention further comprises a protrusion from the base notched on its underside, an instrument, and a protrusion from the instrument, wherein the base has a protrusion connecting to the underside of the leg, said underside having notches, and wherein said instrument has a protrusion facing the notched region on the lens system, said protrusion of the instrument engaging the notches of the lens system. Another embodiment further comprises a protrusion from the lens system, an instrument, and a set of notches on the instrument facing the bottom of the leg of the lens system, wherein the lens system has a protrusion on the underside of the leg, said underside having at least one protrusion, and wherein said lens system's protrusion faces the instrument, said protrusion of the lens system engaging the notches of said second instrument.

In one embodiment, the lens system's base and the instrument have a plurality of matching protrusions on one and depressions on the other at progressively different angles at different distances from the tip of the instrument. This last embodiment may further comprise a spring, connected to the base, operating to reversibly lock and unlock said protrusions and depressions.

Another embodiment further comprises a clipping mechanism attached to the lens system.

In one embodiment, the lens system has a means for rotating the lens on the axis of the leg.

Another embodiment further comprises a set of gear teeth on the instrument and an interlocking gear on the base of the lens system, wherein the base gear is operative in its movement to adjust the lens to maintain its center of sight on the working area at each distance from the working area.

In one embodiment, an electronic mechanism adjusts the angle of said lens system to maintain the line of sight on a working area, with simultaneous movement in distance and angle.

Another embodiment further comprises at least a second lens on said lens system.

Introduced for the first time is a device for maintaining a central line of sight on a working area, comprising a multifocal lens connected to a lens system, with its central line of sight on the working area of said instrument. Another embodiment further comprises a means for maintaining the central line of sight on the working area from different distances of the lens from the working area by simultaneously adjusting the angle of the lens system.

Introduced for the first time is a device for maintaining a central line of sight on a working area, comprising a. a lens system, comprising at least one lens with a central line of sight directed to the working area of a second instrument, a lens holder holding the lens system, a leg attached to the lens holder on a first side of the leg, a base attached to the leg on a second side of the leg, b. an instrument to which the base is attached on the second side of the base, c. a groove in the instrument, said base fitting into said groove at an angle of 180 degrees to the length of the instrument. d. a pin, inserted into said base and said instrument at an angle perpendicular to the length of the instrument.

Another embodiment further comprises a set of pressure and limiter ribs on the instrument facing the sides of the base.

Introduced for the first time is a method of mechanically adjusting the spatial relationship of the central line of sight of a lens system to a working area, wherein, as title distance of the lens system from the working area changes, the angle of the lens to the working area in at least one dimension mechanically adjusts to maintain the central line of sight on the working area.

Claims

WHAT IS CLAIlMED IS:

1. An device for maintaining a central line of sight on a working area, comprising a. a lens system, comprising at least one lens with a focal point at the working area of an instrument, a lens holder holding the lens system, a leg attached to the lens holder on a first side of the leg, and a base attached to the leg on a second side of the leg, b. an instrument to which the base is attached, c. means for centering the central line of sight of the lens on a working area as the base changes distance from the working area.

2. The device of claim 1, wherein at least one lens is a multifocal lens.

3. The device of claim 1, wherein the lens holder has a means for rotating the lens.

4. The device of claim 1, wherein the base is attached non-fixedly to the instrument.

5. The device of claim 1, wherein the base is attached to an arm of the instrument.

6. The device of claim 1, further comprising a protrusion from the base notched on its underside, an instrument a protrusion from the instrument, wherein the base has a protrusion connecting to the underside of the leg, said underside having notches, and wherein said instrument has a protrusion facing the notched region on the lens system, said protrusion of the instrument engaging the notches of the lens system.

7. The device of claim 1, further comprising a protrusion from the lens system, an instrument, a set of notches on the instrument facing the bottom of the leg of the lens system, wherein the lens system has a protrusion on the underside of the leg, said underside having at least one protrusion, and wherein said lens system's protrusion faces the instrument, said protrusion of the lens system engaging the notches of said second instrument.

8. The device of claim 1, wherein the lens system's base and the instrument have a plurality of matching protrusions on one and depressions on the other at progressively different angles at different distances from the tip of the instrument.

9. The instrument of claim 8, further comprising a spring, connected to the base, operating to reversibly lock and unlock said protrusions and depressions.

10. The device of claim 1, further comprising a clipping mechanism attached to the lens system.

11. The device of claim 1, wherein the lens system has a means for rotating the lens on the axis of the leg.

12. The device of claim 1, further comprising , a set of gear teeth on the instrument, an interlocking gear on the base of the lens system, wherein the base gear is operative in its movement to adjust the lens to maintain its center of sight on the working area at each distance from the working area.

13. The device of claim 1, further comprising an electronic mechanism of adjusting the angle of said lens system to maintain the line of sight on a working area, with simultaneous movement in distance and angle.

14. The device of claim 1, further comprising at least a second lens on said lens system.

15. A device for maintaining a central line of sight on a working area, comprising a multifocal lens connected to a lens system, with its central line of sight on the working area of said instrument

16. The device of claim 15, farther comprising a means for maintaining the central line of sight on the working area from different distances of the lens from the working area by simultaneously adjusting the angle of the lens system.

17. A device for maintaining a central line of sight on a working area, comprising a. a lens system, comprising at least one lens with a central line of sight directed to the working area of a second instrument, a lens holder holding the lens system, a leg attached to the lens holder on a first side of the leg, a base attached to the leg on a second side of the leg, b. an instrument to which the base is attached on the second side of the base, c. a groove in the instrument, said base fitting into said groove at an angle of 180 degrees to the length of the instrument, d. a pin, inserted into said base and said instrument at an angle perpendicular to the length of the instrument.

18. The device of claim 17, further comprising a set of pressure and limiter ribs on the instrument facing the sides of the base.

19. The method of mechanically adjusting the spatial relationship of the central line of sight of a lens system to a working area, wherein, as the distance of the lens system from the working area changes, the angle of the lens to the working area in at least one dimension mechanically adjusts to maintain the central line of sight on the working area.