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Claims  |
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What is claimed is:
1. A laser device for attachment to an apparatus for providing pictures of
a target area in a person, said laser device comprising:
a laser head including a first laser source radiating a focused beam in a
first plane and visible as a first line in the target area, a second laser
source radiating a focused beam in a second plane and visible as a second
line in said target area, said second plane intersecting said first plane
at an angle, said focused beams being in an intersecting relationship from
said head to said target area;
a moveable carriage in the laser head moveable in a first direction and
carrying both the first laser source and the second laser source together
for movement in a first direction;
a moveable support means in the carriage for supporting both the first
laser source and the second laser source for travel together relative to
said carriage in a second direction orthogonal to said first direction;
means for moving the carriage and the support means in the orthogonal
directions and thereby moving said first laser source perpendicular to
said first line and for moving said second laser source perpendicular to
said second line; and
means for directing said focused beams emanating from the laser sources
toward the lesion and directing their intersection as a cross line for
marking an insertion location for a biopsy needle in said target area and
providing an intersecting line from said insertion location to align the
needle during insertion to the lesion.
2. A device for locating and guiding a biopsy needle in accordance with
claim 1 including means for mounting said first and second laser sources
in said laser head at locations fixed with respect to each other and for
radiating said beams to intersect and form the intersecting line, said
means for directing including a mirror reflecting radiation from said
first laser source toward said target area, and including a beam splitter
positioned on said axis to reflect said radiation from said second laser
source toward said target area, said radiation from said first laser
source passing through said beam splitter to provide intersecting beams
projectable as the cross line.
3. A device for locating and guiding a biopsy needle in accordance with
claim 2 wherein said mirror and said beam splitter are pivoted about axes
fixed with respect to each other, and compensating means for pivoting said
mirror and said beam splitter as said moveable carriage and moveable
support means moves said focused beams.
4. A device for locating and guiding a biopsy needle in accordance with
claim 3 wherein said first and second laser sources are mounted on said
moveable carriage which is moveable in a plane parallel to said target
area in two orthogonal directions, said compensating means comprising cam
means positioned adjacent to said carriage and extending in the two
directions of orthogonal movement, said compensating means further
comprising cam followers secured to said mirror and beam splitter and
engaging said cam means to rotate said mirror and beam splitter in
accordance with the movement of said carriage.
5. Apparatus for use in X-ray examination and diagnostic procedures
comprising:
an X-ray machine having an X-ray radiation head mounted in spaced relation
to a patient and specimen supporting platform for supporting a specimen, a
clamping means mounted in spaced parallel relation to said platform to
clamp the specimen against said platform and against movement relative to
the X-ray machine, said clamping means having an opening exposing a
portion of the specimen;
indicia associated with the clamping means for locating a lesion on an
X-ray picture by means of coordinates showing in the X-ray pictures taken
by the X-ray radiation head;
a laser head detachably supported on said X-ray machine between said X-ray
radiation head and the specimen supporting platform;
first and second laser sources mounted in said laser head and radiating
focused beams in first and second planes intersecting along an
intersecting line and providing cross lines intersecting on said portion
of the specimen and lying within said opening;
means for moving the laser head to shift the laser head and the cross lines
to a position in accordance with the coordinates location of the lesion as
shown by the X-ray picture; and
a biopsy needle having a hollow sharpened end at one end for insertion into
the specimen to remove a core sample of the specimen, said needle at the
other end receiving the cross lines which appear as a dot on the other end
of the needle for locating the axis of said needle with respect to said
specimen during insertion of the needle for removal of said core sample.
6. Apparatus for use in X-ray examination and diagnostic procedures in
accordance with claim 5 wherein the X-ray radiation from said X-ray
radiation head to the exposed portion of said specimen is substantially
along the the intersecting line extending to said first and second laser
sources.
7. Apparatus for use in X-ray examination and diagnostic procedures in
accordance with claim 6 wherein said first and second laser sources are
supported on a carriage movable in two orthogonal directions in a plane
parallel to said platform, said cross lines formed by beams are
perpendicular, said carriage being movable in directions parallel to each
of said lines.
8. Apparatus for use in X-ray examination and diagonistic procedures in
accordance with claim 7 wherein said opening in said clamping plate is
rectangular having sides extending parallel to said lines defined by said
beams, said indicia being located on said clamping plate along the sides
of said opening for providing the coordinates for use in correlating
biopsy samples with lesion locations as shown in X-rays.
9. Apparatus for use in X-ray examination and diagnostic procedures in
accordance with claim 8 including means for redirecting said beams as said
carriage is moved in either of said two directions.
10. Apparatus for use in X-ray examination and diagnostic procedures in
accordance with claim 9 wherein means for redirecting said beams includes
orthogonally disposed cams each of which extends in one of the directions
of carriage movement and controls the direction of radiation of one of
said laser sources in dependence on the position of the carriage in its
movement.
11. A method of locating and obtaining a biopsy of a lesion in a specimen
comprising:
clamping a specimen with clamping means in a fixed position in an X-ray
machine;
radiating the specimen with X-rays to form an X-ray picture of the specimen
to locate a lesion;
providing indicia means associated with the clamping means for locating a
lesion on said X-ray picture by means of coordinates;
noting the coordinates for the lesion from the indicia means;
generating laser beams to provide two laser beams focused as intersecting
planes emanating from a location along the line of the X-ray radiation;
moving and positioning the laser beam at the respective coordinate
positions on the clamping means and in accordance with the coordinate
locations of said lesions as shown by the X-ray picture;
applying the tip of a biopsy needle to the intersection on the specimen of
the planes formed by the laser beams; and
orienting the biopsy needle while inserting it into the specimen using the
intersection of the laser beam planes to maintain the orientation of said
needle at the lesion coordinates the taking a biopsy sample of the lesion.
12. Apparatus for locating and guiding a biopsy needle in relationship to a
breast immobilizing framework comprising:
a breast supporting platform, including a clamping means having an opening
through which access may be had to a breast clamped to said platform;
a frame;
an X-ray device providing a source of X-rays mounted on said frame in
spaced relation to said platform to radiate a breast supported on said
platform to provide an X-ray picture of a lesion in a breast;
indicia associated with the opening in the clamping means and providing on
the X-ray picture orthogonal coordinates to locate a lesion;
a laser head detachably mounted on said frame between said source of X-rays
and said platform, said head including a first laser source radiating a
focused beam in a first plane visible as a first line on said breast, a
second laser source radiating a focused beam in a second plane visible as
a second line on said breast and intersecting said line from said first
laser source at 90.degree.;
translating means for moving said first laser source perpendicular to said
first line and for moving said second laser source perpendicular to said
second line and to the coordinates for the lesion as seen in the X-ray
picture; and
the intersection of said beams from said first and second laser beams
providing a line aligned along a travel path of X-rays from the X-ray
source to the lesion for locating a needle insertion point and maintaining
said needle aligned with the lesion. |
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Claims |
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Description |
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The present invention relates to an instrument for use in guiding and
directing a biopsy needle in obtaining a specimen of human tissue, and
more specifically relates to apparatus for projecting a pair of laser
beams to define the location of an internal lesion and guide a biopsy
needle to the lesion.
BACKGROUND OF THE INVENTION
In recent years the public has become very aware of the importance of X-ray
examination of women's breasts in the control and cure of breast cancer.
The early detection of cancerous tumors is recognized as significantly
improving the chances of successful treatment. As a consequence, women of
a certain age or genealogical background are subject to X-ray examination
of their breasts at frequent intervals. Such examination often detects
tumors or lesions which are of a questionable character, it being
impossible to determine from the X-ray whether the tumor or lesion is
malignant or benign. In such situations, it is normal to take a specimen
or biopsy of the tumor or lesion to permit a careful examination of the
abnormal tissue.
The most common means of taking a biopsy of a tumor or lesion in a woman's
breast is by using an elongated needle which may be inserted with a rotary
movement to cut a core sample of tissue in the area of the tumor or
lesion. The needle is equipped with suction means to aid in extracting the
cylindrical section of tissue. Since the current trend is toward early
detection through frequent examination, the tumor or lesion which is to be
checked through the biopsy is often very small and barely discernable on
the X-ray. With the tumor or lesion often being well below the skin
surface, it is extremely difficult to insert the biopsy needle with
sufficient accuracy to engage and sample the area of tissue that is of
interest and requires further testing.
In the presently used procedure, the breast of the patient is compressed
against a horizontal surface below which the X-ray film is positioned. The
compressing member is placed above the breast, clamping it against the
surface, leaving a panel of skin exposed through a rectangular opening
which has indicia on the sides of the opening to aid in establishing the
location of the tumor discovered on the X-ray. By establishing the
coordinates of the location of the tumor from the X-ray, a mark is placed
on the location on the exposed skin using the indicia beside the opening
to show where the biopsy needle should be inserted. An additional X-ray is
taken to show the depth of the tumor so that the needle may be inserted
and the specimen taken at the proper depth below the skin surface. After a
biopsy specimen has been taken, another X-ray is taken to assure that the
biopsy specimen is from the suspected tissue.
Because of the limited size of the tissue to be sampled and the possible
errors in correlating the location of the needle insertion with the
location of the tumor as shown on the X-ray, it is not unusual for many
needle insertions to be required before achieving the proper location of
the needle with respect to the tumor. The procedure causes considerable
pain and discomfort and the prolongation resulting from the techniques
employed suggest that improved techniques are required.
One attempt at locating the biopsy needle more precisely with respect to an
X-ray picture of a tumor has involved the use of movable cross wires to
create a shadow produced by an incandescent lamp to locate the needle
insertion point on the skin. This technique has not proven to be
particularly helpful, since the shadow image of the wires was not sharp
enough to give a precise location and the normal ambient light in the area
was usually too high to permit good visibility of the shadow image of the
wires.
Another approach involved use of a laser dot which was projected in from
the side to spot the needle insertion location on the skin. The angle at
which the laser beam was projected tended to introduce errors since any
deflection of the skin would cause the laser spot to shift location.
Another problem associated with the biopsy is the difficulty of inserting
the needle in a direction perpendicular to the horizontal support surface.
The selected location on the skin is intended to be directly over the
tumor, so the needle must be inserted vertically if it is to engage the
tumor. However, the biopsy needle is designed to be rotated as it is
inserted. Otherwise, the sharp angled end on the needle will tend to
deflect the path of the needle to one side as it is inserted. Experience
has revealed that it is very difficult to rotate the biopsy needle and
maintain its vertical orientation as it is inserted. Accordingly, it would
be desirable to provide means for locating the insertion point for a
biopsy needle and for guiding the needle to maintain its vertical position
as it is inserted.
SUMMARY OF THE INVENTION
The present invention involves method and apparatus for obtaining a biopsy
specimen after having identified a tumor or lesion through X-ray
examination. The X-ray machine in connection with which the invention is
used has an X-ray head supported above a specimen supporting platform with
means provided to immobilize or clamp the specimen to be examined, as for
example a woman's breast, against the platform An X-ray film is disposed
on the platform so that the X-rays radiated from the head pass through the
specimen and provide an image of the specimen on the film. When a possible
cancerous tumor or lesion is noted in the X-ray, it often becomes
desirable to take a biopsy for further testing to ascertain the nature of
the tumor. In order to take the biopsy, it is necessary to identify on the
patient's skin exactly where the biopsy needle should be inserted to
engage the tumor or lesion observed on the X-ray.
In the method and apparatus of the present invention, a pair of laser
sources are detachably mounted between the X-ray head and the specimen
platform to provide two aligned intersecting laser beams that are directed
along the same common axis as the radiated X-rays. The laser beams are
focused to be visible on the surface of the X-rayed specimen as a pair of
lines which intersect at 90.degree. to each other. The laser sources are
mounted on a carriage which is movable along one path parallel to one of
the lines and along another path parallel to the other line. Thus, by
moving the carriage along either of two mutually perpendicular paths, the
location of the intersection of the lines formed by the laser beams may be
moved to any desired location. The clamping means or plate, which overlies
the specimen platform and clamps the specimen, is formed with a
rectangular opening in which a portion of the specimen is exposed. The
specimen is disposed so that the tumor or lesion to be biopsied lies under
the skin which is exposed through the opening in the clamping means. In
order to insert the biopsy needle accurately, it is necessary to provide a
marking or indication on the exposed skin as to where the biopsy needle
should be inserted to engage the tumor or lesion indicated by the X-ray. A
scale is used to establish the coordinates of the tumor location in the
clamping means opening. These coordinates are then used to position the
laser beam lines intersecting at the location on the skin above the tumor.
The laser beams are generated by diode lasers generating an oval dot which
is directed through a cylindrical lens to expand the beam to form a line
which is reflected from a mirror onto the specimen. The beams as they are
directed toward the specimen are substantially coaxial, appearing to
emanate from a single source. The laser source closest to the specimen is
reflected by a beam splitter which only reflects 50% of the impinging
beam. The beam from the laser source more remote from the specimen is
first reflect by a mirror and that beam is directed through the beam
splitter toward the specimen, with 50% of the beam passing directly
through the beam splitter and to the specimen and 50% being reflected.
This results in the two beams being coaxial and intersecting as they pass
from the beam splitter to the specimen. The laser head containing the two
laser sources is detachably mounted directly in line with the X-ray head
so that the laser beams engage the specimen along the same line or axis as
the X-rays. This alignment eliminates any errors in using the laser beams
as a locating or indicating means for the tumors which were located from
the X-ray image.
One of the serious problems in using laser beams to target or locate a
position on the skin for inserting a biopsy needle is the fact that the
laser beams may reflect from the clamping means into the eyes of the
person using the instrument or the patient on whom it is being used. If
the lasers used for locating the tumor in the specimen are reflected from
the clamping means into the eyes of the patient or doctor, the apparatus
would not be considered acceptable for this type of use. Accordingly, the
laser beams are provided with compensation means that redirects the beams
as the laser supporting carriage is traversed so that the locating lines
on the specimen remain on the exposed portion of the skin within the
opening in the clamping means. Cams are provided so that as the carriage
traverses in either of the two orthogonal directions, the mirror and the
beam splitter are adjusted to maintain the centering of the laser lines
within the opening in the clamping means.
The elements of the laser sources, including the diode lasers and the
lenses as well as the mirror and beam splitter, are all mounted in a
single Delrin block which forms the major portion of the movable carriage.
The block provides a vibration-free and dimensionally precise means of
mounting the laser sources and the adjustable mirror and beam splitter.
Drilled pockets receive the diode lasers and the cylindrical lenses.
Drilled holes are provided to receive axles that pivot the mirror and beam
splitter and to receive guide rods for mounting the block for transverse
movement.
The carriage providing the movable mounting for the laser sources includes
an inverted U-shaped frame mounted for what will be termed front-to-back
movement. The carriage frame supports the Delrin block for left/right
movement with respect to the frame. Reversible motors are provided to
drive the block with respect to the carriage and the carriage with respect
to the laser head to position the laser sources and the laser beam lines
with respect to the specimen or the opening in the clamping means.
The visible lines produced by the laser beams on the skin of the specimen
are focused to have a width of 0.020 inches located about 18 inches from
the laser source. Under the typical clamping pressure of about 30 pounds,
the breast of the patient would typically space the clamping means from 1
to 3 inches from the supporting platform. The flesh of the specimen tends
to bulge upwardly through the opening in the clamping means, making it
difficult to fix the location on the skin with the coordinate location of
the tumor or lesion as obtained from the X-ray. However, the laser beam
line extends to a point adjacent the indicia on the edge of the opening,
facilitating the alignment of the laser beam lines with the proper
coordinate location.
Once the laser beam lines have been properly located by movement of the
carriage with the motor drives, the intersection of the lines is used as
the location for inserting the biopsy needle into the skin. Since the
needle is about 0.090 inches in diameter, an incision is normally made
before inserting the needle. The needle is connected to a source of
suction to withdraw a cylindrical core or sample. The angled end of the
needle is sharpened but must be rotated as it is inserted to cut the
specimen to be removed. It is difficult to maintain the needle in a proper
vertical orientation as it is inserted while rotating at the same time.
Any deviation from the vertical orientation tends to introduce an error,
since the insertion location is predicated on going vertical downwardly to
the tumor or lesion location.
The laser beam lines make it possible to accurately maintain the vertical
orientation of the biopsy needle as it is inserted. The nature of the
laser beam is such that it provides a sharp, well defined line of light at
the surface of the specimen and also at a level 10 inches above where the
upper end of the biopsy needle terminates. It is therefore possible to use
this extended intersection of the laser beams to establish a line along
which the biopsy needle must move to properly engage the tumor. After the
tip of the needle is located and engaged with the skin, the intersection
of the laser beam lines is positioned on the outer end of the needle in an
axially aligned location to assure that the needle remains vertical as it
is rotated and forced downwardly into the specimen. As long as the axis of
the needle is maintained centered on the intersecting beams, the vertical
positioning of the needle will be maintained. The fact that the
intersection of the beam emanates along the line of the X-ray radiation
assures that the biopsy needle will be inserted accurately at the surface
of the specimen and will move inwardly to engage the tumor or lesion. As
long as the coordinates or the tumor are taken accurately from the X-ray
image, the apparatus and method of the present invention provides a
completely reliable method of obtaining a biopsy of a tumor or lesion
located on an X-ray.
Accordingly, it is an object of the present invention to provide an
improved method and apparatus for locating an insertion point and guiding
a biopsy needle to engage the tumor or lesion, the location of which has
been established by an X-ray.
A further object of the present invention is to provide a laser beam
locating and guiding means for use in taking a biopsy of an X-rayed
specimen, the means being removably mounted on the X-ray machine between
the X-ray head and the specimen.
It is a further object of the present invention to provide an improved
laser beam locating and guiding means having laser sources supported by a
carriage for movement on two mutually perpendicular axes to produce
intersecting lines on a specimen, including means for compensating for
carriage movement so that the lines are only shifted laterally.
These and other objects of the invention should be apparent from the
following detailed description for carrying out the invention when read in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an X-ray machine equipped with a laser beam
head embodying the present invention;
FIG. 2 is a plan view of a clamping plate of the type used in X-ray
examination of the female breast;
FIG. 3 is a front perspective view from below of the carriage which
supports the laser beam sources for the laser beam head;
FIG. 4 is an exploded perspective view of the laser diodes and their
supporting block;
FIG. 5 is a diagrammatic view of the laser beam source in various positions
illustrating the compensating mirror movement to maintain the image
position fixed;
FIG. 6 is a top plan view of the laser head with the top wall cut away for
illustrative purposes;
FIG. 7 is a sectional view of the laser head taken on line 7--7 of FIG.6;
FIG. 8 is a sectional view of the laser head taken on line 8--8 of FIG. 6;
FIG. 9 is a diagrammatic view of an alternative embodiment of the
invention; and
FIGS. 10a, 10b and 10c are schematic diagrams of the action of the laser
beam control by the alternative embodiment of FIG. 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1 of the drawings, there is shown an X-ray machine 10
which may take the form of any commercially available machine used for
diagnostic examinations of the female breast as in mammography. With the
recognition of the importance of early detection of cancer in improving
the chances of successful treatment, there is increasing use of such X-ray
machines in early detection of cancerous tumors or lesions. When such
tumors or lesions are noted on X-ray images, it is usually necessary to
take a biopsy of the tumor or lesion for further testing to determine the
nature of the treatment that should be given to minimize the risk to the
patient. Because of the small size of the tumors or lesions in this early
detection stage, it is often difficult, time consuming and painful to the
patient to obtain the desired biopsy of the tumor or lesion.
The X-ray machine 10 includes an X-ray head 12 from which the X-ray
radiation takes place. The radiation is directed toward a support platform
14 which is adjustable in height to support the specimen to be examined,
such as a female breast. The machine 10 is provided with a support column
16 and a body portion 15. The platform 14 includes means for disposing the
X-ray film beneath the specimen so that when exposed to X-ray radiation
from the head 12, an image of the specimen is produced on the film. The
illustrated machine 10 is commercially available from Ausonics Corporation
of Finland. Manifestly, X-ray machines of other companies may be used with
the present invention.
In order to immobilize and clamp the specimen during the X-ray examination,
it is common practice to use paddle or clamping means 20, as shown in FIG.
2. The clamping means 20 is mounted in parallel spaced relation to the
support platform 14 and is adapted to apply a pressure of on the order of
thirty pounds to the specimen during the initial X-ray examination. The
pressure is reduced substantially during the biopsy. In the examination of
a female breast, the clamping means 20 would be spaced 2 to 7 cm from the
upper surface of the platform 14. To expose a portion of the specimen so
that a biopsy may be taken by a biopsy needle 21, the clamping means 20 is
formed with a rectangular opening 22. At the edges of the opening 22 there
are indicia 24 which permit the designation of locations with the opening
22 by coordinates such as C-1.5, indicating a location aligned with the
letter C and the number 1.5. It is known to use such a clamping means
provided with this type of indicia to locate a tumor from which a sample
is to be taken by a biopsy needle. These clamping means are conventional
in the art and need not be described in detail herein. The method and
apparatus of the present invention provides a more accurate means of
locating such a tumor and performing a biopsy than is now possible with
presently known methods and apparatus.
The X-ray machine 10 is provided with means for detachably mounting a laser
head 24 immediately below the X-ray head 12 so that the laser beams are
radiated substantially along the same axis as the X-rays radiated toward
the platform 14.
As shown in FIGS. 6-8, the laser head 24 is enclosed in a housing 26 which
is closed on all sides except for an opening 26a in its bottom wall, as
shown in FIG. 7. The opening 26a is for the purpose of allowing laser
beams to be directed from within the housing 26 downwardly onto a specimen
on the platform 14. Within the housing 26 there is secured a frame 28
which supports a movable carriage 30. The carriage 30 is supported and
guided for horizontal movement by a pair of spaced parallel rods 32
secured to opposed front and back walls 34 and 36 respectively of the
frame 28, as shown in FIG. 6.
The carriage 30 is of generally inverted Ushaped configuration having a
central portion 30a which extends across beneath the rods 32 and
terminates at depending sidewalls 30b. As shown in FIGS. 3 and 8, the
carriage 30 is formed with upwardly extending ears or tabs 30c which mount
bearings for supporting the carriage for sliding movement along the rods
32. In order to traverse the carriage forwardly and backwardly along the
rods 32, a threaded feed screw or shaft 38 is provided between the rods 32
and journaled for rotation in the walls 34 and 36, as shown in FIG. 6. The
feed screw 38 is rotated by a reversible motor 40 which drives the screw
38 through an idler gear 42 engaged by spur gears on the motor shaft and
the screw shaft 38. At the middle of the carriage 30, there is provided a
feed nut 44 which is secured to wall 30a of the carriage and which has a
threaded opening to receive the screw shaft 38. Thus, as the screw shaft
38 is rotated by the motor 40, the carriage is caused to traverse along
the screw 38 and the rods 32.
As is best shown in FIGS. 3 and 4, there is provided a laser support block
46 which is mounted for lateral movement with respect to the carriage 30.
The block 46 provides support for the means for generating the laser beams
which are used for locating and guiding a biopsy needle as will be
explained in detail below. The sidewalls 30b of the carriage 30 fixedly
mount the ends of two parallel guide rods 48 and 50 which extend through
bored holes in the block 46. The block 46 is preferably machined from
Delrin, which is self-lubricating and requires no bearings to mount the
block 46 for sliding movement with respect to the rods 48 and 50. As shown
in FIG. 7, there is provided a reversible motor 52 mounted on the carriage
sidewall 30b to drive a feed screw 54 which engages a feed nut (not shown)
on the block 46 in order to drive the block 46 along the rods 48 and 50.
An idler gear and spur gears (not shown) drivingly connect the motor 52 to
the feed screw 54. From the foregoing, it may be understood that the block
46 is movable laterally with respect to the carriage 30 and that the
carriage 30 may traverse forward and back with respect to the mounting
frame 28. This arrangement allows the block 46 to be moved front-to-back
and side-to-side in a plane parallel to and spaced above the platform 14
and the clamping means 20. The block 46 provides a very inexpensive manner
in which to precisely position the lasers and lenses and to maintain their
positions despite a considerable handling of the apparatus during its
attachment and detachment to the X-ray machine.
Supported within the block 46 are two laser diodes 56 as shown in FIG. 4.
The laser diodes 56 are commercially available and are of the type
producing an oval beam which may be focused to a line using a cylindrical
lens 58. As shown in FIGS. 3 and 4, the block 46 has bored therein two
holes 60 and 62 which receive and mount a laser diode 56 in each.
Intersecting bored holes 64 and 66 receive and mount the cylindrical
lenses 58. The laser diodes 56 are sufficiently recessed within the bored
holes 60 and 62 to avoid interference with the lenses 58. The holes 60,
62, 64 and 66 are precision bored to snugly receive the diode lasers 56
and the cylindrical lenses 58 and to position the laser beam generating
elements accurately with respect to each other.
Also mounted in the block 46 is a mirror 68 which is disposed at a
45.degree. angle to the uppermost laser beam and which is mounted for
pivoted movement about an axis 70 which lies in a vertical plane through
the axis of the lowermost laser. Thus, the mirror 68 reflects the narrow
beam downwardly in a vertical plane which intersects the vertical plane
including the other laser beam.
Located immediately below the mirror 68 is a beam splitter 72 which will
reflect 50% of the beam impinging on its surface and will pass through 50%
of the beam. The beam splitter 72 is mounted for rotation about an axis 74
and is disposed at a 45.degree. angle to the downwardly directed beam from
the uppermost laser and at a 45.degree. angle to the lowermost laser which
is directed horizontally into the beam splitter 72. As a result, the beam
splitter produces a downwardly directed beam which is the combination of
50% of the reflected beam from the lowermost laser and the 50% of the beam
passed through from the uppermost laser. The two downwardly directed beams
are intersecting and produce cross lines at the specimen or in the opening
22 in the clamping means 20.
As explained above, it is important to maintain the laser beam line within
the opening 22 on the clamping means 20, since reflections of the laser
beam from the surface of the clamping means is very distracting and
objectionable. Accordingly, means are provided in the laser head 24 to
compensate for the traversing of the carriage 30 or the block 46 by
adjusting the mirror 68 or the beam spl | | |
