Generator for generating one or more dots or lines of light

A light beam generator provides a thin ray or plane of light of high intensity with a non-laser light source. Light emanating from a light source such as a quartz-halogen bulb is applied to a convex reflector or negative lens to demagnify the image of the light producing element. The demagnified image is passed through a refracting means such as convex lens to form a thin ray or plane of light. The reflective or refractive elements can be spherical or cylindrical depending on whether a dot or line of light is desired.

The present invention relates to an improved light beam generator. More 
particularly, the present invention relates to a generator capable of 
generating beams of light of generally high intensity but without the need 
to use a laser or similar light source. 
While not limited thereto, the light beam generator of the present 
invention may find use in the field of radiological medical equipment. A 
patient must be accurately positioned with respect to the radiation beam 
of such equipment in order to achieve the desired degree of effectiveness 
in diagnosis or therapy while minimizing undesirable side effects. Since 
the radiation beam is not visible to the eye, some means must be provided 
to identify and locate the beam and insure that it will impinge on the 
correct portion of the patient. For this purpose, a reference light 
pattern bearing a predetermined relationship to the radiation beam may be 
generated. As the patient is oriented with respect to the radiation beam, 
a pattern of light is applied to the patient and used to properly position 
the patient with respect to the radiation beam. When the light is in the 
form of a ray, a dot of light is formed on the patient when the light is 
so applied. When the light is in the form of a plane, a line of light is 
formed on the patient. 
In radiological equipment of the axial tomographic imaging type, a plane of 
light may be generated to lie in the imaging plane of the equipment. When 
the patient is positioned in the equipment, a line will appear on the 
patient indicative of the imaging plane. The radiologist can thus easily 
identify the plane that will be imaged in a subsequent scanning operation. 
Planes or dots of light may also be utilized to indicate the boundaries or 
extent of a conventional radiological beam. For example, planes of light 
may be arranged in a cross to indicate the central axis of a radiological 
beam. A rectangle of planes or a plurality of dots may be employed to mark 
the extent of the beam established by an x-ray collimator. 
U.S. Pat. Nos. 4,730,895, 4,337,502 and 4,242,587 to the same assignee as 
the present application show various types of alignment systems utilizing 
beams of light. 
When used for the above described purposes, it is preferable that the 
planes of light be narrow in width and that the dots be small in order to 
insure accurate alignment or positioning. It is further desirable that the 
beams of light be sufficiently bright so that the lines or dots created 
thereby can be easily observed under ambient lighting conditions. 
Heretofore, laser light sources have frequently been used in light beam 
generators in order to obtain sufficient brightness, narrowness, and depth 
of field in the lines or dots. While possessing the advantages of 
intensity and low divergence, the use of laser light sources is attended 
by a number of disadvantages. Laser light sources, such as those of the 
helium-neon type, are rather bulky devices. This may hinder or prevent 
their positioning at the appropriate location in the radiological 
equipment, for example, within a computerized axial tomographic x-ray 
machine. Laser light sources also tend to be rather expensive. Laser light 
sources, such as He-Ne lasers that produce visible light, require 
excitation by potentially lethal voltages which are undesirable in any 
case and particularly in a medical diagnosis or treatment environment. 
It is, therefore, the object of the present invention to provide an 
improved light beam generator that is capable of providing light beams of 
high intensity, narrowness, and sufficient depth of field without 
employing a laser light source. The advantages of a laser light source are 
thus retained while the disadvantages are lessened or eliminated. 
The unique construction of the present invention permits the use of low 
cost light sources, such as quartz-halogen incandescent light bulbs or 
light emitting diodes of the ultra bright type as the light source. 
Briefly, the light beam generator of the present invention employs a small 
light source or a light source having a small light emitting element of 
the above type. The image of the light emitting element of the light 
source, such as the filament, is demagnified, as by a convex mirror or 
negative lens. A refracting means, such as a convex lens of the 
cylindrical or spherical type, forms the demagnified image into a bright 
beam of low divergence. The lens may be stopped down to assist in forming 
the beam. 
The invention will be further understood by reference to the following 
detailed description of preferred embodiments, taken in conjunction with 
the drawing.

As shown in FIG. 1, light beam generator 30 of the present invention is 
provided with window 32 through which a plane of light may emerge. 
Light beam generator 30 includes housing 34 having base member 36. A light 
source 38 is secured to base member 36 by bracket 40, shown in FIG. 2. 
Light source 38 may be a small bulb of the incandescent quartz-halogen 
type. For example, light source 38 may be the quartz-halogen light bulb 
sold by Welch Allyn under the designation #01075. It would also be 
possible to utilize a light emitting diode for the light source. For 
example, the light emitting diode manufactured and sold by Stanley under 
the designation H-3000 would be suitable for use as light source 38. A 
xenon tube or other suitably bright, incoherent light source can also be 
utilized. The light source may also comprise the light emitting end of an 
optical fiber. 
Light source 38 is connected to an appropriate power supply. The power 
supply may include a transformer that steps down power mains voltage, such 
as 110 volts AC, to a lower, safer voltage, such as 5-6 volts. A similar 
low-voltage power supply may be used for a diode light source. In either 
event, the high voltage power supplies heretofore required by lasers are 
avoided. 
The light emitting element in light source 38 of the incandescent type is a 
coiled filament. The light bulb includes an integral lens in the end of 
the bulb that focuses the light emanating from the coiled filament. 
Light shield 39 may be mounted behind light source 38. 
The light output of light source 38, and particularly that from the coiled 
filament is applied to small diameter, convex cylindrical mirror 44 
mounted on bracket 46 on end wall 48 of housing 34. Cylindrical mirror 44 
diverges the light from light source 38 in the well known manner of a 
convex mirror. This divergence gives the appearance of a small point light 
source resulting in a demagnification or reduction in the image of the 
coiled filament from light source 38. Mirror 44 may be formed of a 
silvered glass rod, or the like. A portion of the cylindrical mirror 44 
may be flattened to assist in affixing the mirror to bracket 46. 
Plate 50, parallel to end wall 48, is mounted in housing 34 on the opposite 
side of light source 38 from mirror 44. As best shown in FIG. 2, plate 50 
contains slot 52. A plano convex cylindrical lens 54 is mounted on plate 
50 over slot 52 to receive the light from cylindrical mirror 44 passing 
through slot 52. The plano convex lens focuses the diverged light from 
cylindrical mirror 44, forms same into a plane of light, and collimates or 
renders the rays of light emitted by lens 54 substantially parallel. The 
side portions of lens 54 may be rendered opaque by coating 56 to stop down 
the lens and leave a small central slit in the center thereof The action 
of lens 54 and the stopping down of lens 54 by aperture 52 and coatings 56 
increases the depth of field of the line of light generated by lens 54. 
The action of lens 54 is thus one of generating a high intensity, narrow 
beam of light with very small divergence. 
Mirror 60 is mounted on plate 62 set at a 45.degree. angle with respect to 
plate 50. Mirror 60 receives the light emitted by lens 54 and directs a 
high intensity thin plane of light out window 32 parallel to base 36. 
The intensity and thinness of the plane of light generated by light source 
30 arises from the use of the small filament image of high intensity light 
source 38, the demagnification of the light source image by convex 
cylindrical mirror 40, and the focusing of the demagnified filament image 
into a narrow line by stopped-down plano convex cylindrical lens 54. 
It will be appreciated that if a ray of light, rather than a plane of 
light, was desired, cylindrical mirror 44 could be replaced with a 
spherical mirror and a spherical lens used instead of a cylindrical lens. 
Or, a plano-convex cylindrical lens, such as lens 54, could continue to be 
used with a spherical mirror to generate a line of light. 
FIG. 3 shows a typical application for the light source 30 of the present 
invention in computerized axial tomographic x-ray machine 80. X-ray 
machine 80 has gantry 82 containing the x-ray generators and receptors 
arranged about a central opening 84. The x-ray images produced by machine 
80 are resolved in a vertical plane. 
X-ray machine 80 also contains patient support 86 containing cradle 88. 
When the patient is to be examined, he/she is placed on cradle 88 and 
advanced into opening 84 of gantry 82. 
Light beam generator 30 of the present invention may be employed to 
generate a vertical plane corresponding to the imaging plane of machine 
80. If desired, another light beam generator 30 may be employed to 
generate a plane of light normal to the imaging plane that shows the 
center line of opening 84. A cross of light would then appear on the 
patient when positioned within gantry 82. 
Or, a single light beam generator 100 such as that shown in FIG. 4, that 
generates intersecting planes of light may be employed in gantry 82. Light 
beam generator 100 includes housing 102. Light beam generator 100 is shown 
as being of the type that generates two mutually perpendicular, 
intersecting planes of light. For this purpose, housing 102 has a window 
104 that is generally horizontal when light beam generator 100 is oriented 
as shown in FIG. 4. A generally horizontal plane of light may emerge from 
the window 104. Housing 102 includes a generally vertical window 106 
through which may emerge a generally vertical plane of light. This plane 
may diverge vertically and may be directed upwardly toward the horizontal 
plane. The planes of light from windows 104 and 106 will thus intersect in 
front of light generator 100. When applied to an object, a cross of light 
lines will be generated on the object. As noted above, the light beam 
emerging from window 104 may indicate the tomographic plane of 
radiological equipment 80 while the light beam emerging from window 106 
identifies the axis of the equipment and the longitudinal axis of the 
patient, or vice versa. 
As shown in FIG. 4, light beam generator 100 contains base member 110. 
Housing 102 may be fastened to base member 110 by appropriate fasteners 
such as screws 112. 
As best shown in FIGS. 6 and 7, light source 114 is mounted on base 110 
adjacent one end thereof. Bracket 116 may be employed for this purpose. As 
shown in FIG. 6, light source 114 may be oriented generally parallel to 
base 110. Bracket 116 may be mounted on posts 118 fixed to base 110 by 
bolts 120. A light shield 122 is mounted on base 110 adjacent one side of 
light source 114. Light source 114 may be similar to light source 38. 
The light output from the light emitting element in light source 114 is 
projected generally along axis 124 shown in FIG. 7. Mirror 128 is mounted 
on bracket 130 that is fastened to base 110 by bolt 132. Mirror 128 lies 
at an angle of 45.degree. to the axis of projection. Bolt 132 may be 
loosened to pivot mirror 128 to obtain the desired orientation. As shown 
most clearly in FIG. 6, the height of mirror 128 above base 110 is such 
that the upper edge of mirror 128 lies at approximately the center line of 
light source 114. A portion of the light of light source 114 is thus 
reflected by mirror 128 and a portion passes over mirror 128 on axis 124. 
A second planar mirror 134 is mounted on base 110, as shown in FIGS. 7 and 
8 to receive and further reflect the light reflected by mirror 128. The 
plane of mirror 134 lies parallel to the axis of projection 124 of light 
source 114. Mirror 134 is tilted with respect to a normal to base 110, as 
seen in FIGS. 7 and 8. 
As noted above, a pair of posts 118 extend from base member 110 adjacent 
light source 114. A corresponding pair of posts 140 is located at the 
other end of base member 110. 
Posts 118 and 140 mount a pair of small diameter, convex cylindrical 
mirrors and a pair of plano-convex cylindrical lenses. Plate 142 is 
mounted on posts 118 to extend from the posts in the direction of axis 
124. Plate 142 is coupled to plate 144 mounted on posts 140 by means of 
bolt 146 that is threaded in a tapped hole in plate 144. Bolt 146 is 
surrounded by spacer 148. 
A flange 150 depends from plate 142. Flange 150 may be integrally formed 
with plate 142. L-shaped bracket 152 is mounted on flange 150 by bolt 154. 
Portion 156 of bracket 152 contains a slot through which bolt 154 passes 
so that bracket 152 may be moved with respect to flange 150 for focusing 
purposes. Portion 158 of bracket 152 lying normal to portion 156 contains 
small diameter, convex, cylindrical mirror 160. Mirror 160 receives light 
reflected off mirrors PG,13 128 and 134. A portion of cylindrical mirror 
160 may be flattened to assist in affixing the mirror to portion 158. 
Plate 142 contains slot 162 (see FIG. 6). A plano convex cylindrical lens 
164 is mounted on plate 142 over the slot 162 to receive the light from 
cylindrical mirror 160 passing through slot 162. The side portions of lens 
162 are rendered opaque by coating 166 leaving a small central slit down 
the center of the lens. 
Flange 170 depends from plate 144. Flange 170 may be integrally formed with 
plate 144. L-shaped bracket 172 is mounted on flange 170 by bolt 174. 
Portion 176 of bracket 172 contains a slot through which bolt 174 passes 
so that bracket 172 may be moved with respect to flange 170 for focusing 
purposes. Portion 178 of bracket 172 lying normal to portion 176 contains 
small diameter, convex cylindrical mirror 180. Mirror 180 receives light 
from light source 114 projected along axis 124 and over the top of mirror 
128. As with mirror 160, a portion of mirror 180 may be flattened to 
assist in affixing the mirror to portion 178. 
Plate 144 is also slotted. A plano convex cylindrical lens 182 is mounted 
on plate 144 over the slot to receive the light from cylindrical mirror 
180 passing through the slot. The sides of lens 182 are rendered opaque by 
coating 184 leaving a small central portion in the center of the lens. 
In operation, light source 114 is energized by a low voltage source through 
conductors 42. Light is emitted by light source 114 along axis 124. A 
portion of the light is reflected off mirror 128 on to mirror 134. The 
light applied to mirror 134 is, in turn, reflected to convex cylindrical 
mirror 160. The convex cylindrical surface of mirror 160 reflects a 
greatly demagnified or reduced image of the light emitting filament in 
light source 114. The diverged light from mirror 160 is applied to plano 
convex lens 164. Stopped-down lens 164 focuses the image into a thin plane 
of light. 
The light from light source 114 projected along axis 124 passes over the 
top of mirror 128 and is applied to cylindrical lens 180. The image of the 
light producing element in light source 114 is reduced or demagnified by 
lens 110 and applied to plano convex lens 182 where it is focused into a 
thin plane. 
As can be most clearly seen in FIG. 6, convex cylindrical mirror 160 and 
plano convex lens 164 lie at an angle to base 110. The plane of light 
projected from lens 164 is projected toward the plane of light projected 
from lens 182. This angle of projection, plus the divergence of the plane 
of light in the vertical plane causes the plane of light projected by lens 
164 and the plane of light projected by lens 182 to cross. 
The intensity and thinness of the plane of light generated by light beam 
generator 100 arises from the use of a small filament light source, the 
demagnification of the light source by convex cylindrical mirrors 160 and 
180 and the focusing of the demagnified filament image into a line by 
stopped-down plano convex cylindrical lenses 164 and 182. 
FIGS. 10 and 11 show a light source 200 in the form of a row of light 
emitting diodes 202 mounted on bracket 204. The light from the row of 
light emitting diodes may be applied to a small diameter cylindrical 
mirror, such as mirror 44 along the entire axial length of the mirror for 
projection through stopped-down lens 206 to facilitate the generation of a 
plane of light. 
In the alternative, a row of light emitting optical fibers or an 
incandescent light having an elongated filament running parallel to mirror 
44 could be employed for a similar purpose. 
FIG. 12 shows another embodiment of the present invention in which the 
image reduction of light source 208 is obtained with negative lens 210. 
The light bulb comprising light source 208 is oriented so that the side of 
the filament of the light bulb applies light to lens 210. The light bulb 
made and sold by the Osram Corp. under the designation W465 or HPR2 is 
suitable for use as light source 208. Negative lens 210 demagnifies the 
image of the filament of the light source to increase the divergence of 
the light rays. Negative lens 210 may be of the "fisheye" type to maximize 
demagnification. Negative lens 210 is positioned in front of positive, 
convex lens 212 that forms a ray of light. Lens 212 may be stopped down in 
the same manner as lens 54, 164, and 182. Lens 212 may be movable toward 
and away from lens 210 for focusing purposes. 
Various modes of carrying out the invention are contemplated as being 
within the scope of the following claims particularly pointing out and 
distinctly claiming the subject matter which is regarded as the invention.