(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2004/0227998 A1
`(43) Pub. Date: NOV. 18, 2004
`
`Aoshima et al.
`
`US 20040227998A1
`
`(54) LENS, LIGHT IRRADIATION APPARATUS,
`AND LASER POINTER
`
`(52) us. Cl.
`
`.............................................................. 359/641
`
`(75)
`
`Inventors: MasayoshiAoshima, Miyagi (JP); Kyu
`Kanno, Miyagi (JP)
`
`Correspondence Address:
`SONNENSCHEIN NATH & ROSENTHAL LLP
`PO. BOX 061080
`WACKER DRIVE STATION, SEARS TOWER
`CHICAGO, IL 60606-1080 (US)
`
`(73) Assignee: Sony Corporation
`
`(21) Appl. No.:
`
`10/835,669
`
`(22)
`
`Filed:
`
`Apr. 30, 2004
`
`(30)
`
`Foreign Application Priority Data
`
`May 12, 2003
`
`(JP) .................................... P2003—133559
`
`Publication Classification
`
`(51)
`
`Int. Cl.7 ..................................................... G02B 27/30
`
`(57)
`
`ABSTRACT
`
`A lens, a light irradiation apparatus and a laser pointer to
`Which the lens is applied to are provided, in Which eccen-
`tricity, discrepancy of light axes, uneven gap of lens surfaces
`and the like are reduced Without performing positioning of
`respective lenses; and cost of manufacturing a lens having a
`plurality of functions can be reduced.
`
`in
`A lens according to the present invention is the lens,
`Which a light diameter expanding element for expanding a
`diameter of incident light and a light collimating element for
`projecting approximately collimated light after receiving the
`incident light having the diameter thereof expanded by the
`light diameter expanding element are integrally formed in
`advance as a lens of one unit. According to such lens, it is
`possible to control occurrence of the eccentricity, the dis-
`crepancy of light axes and the uneven gap of lens surfaces
`due to a positioning discrepancy between respective lenses,
`in comparison to a lens wherein a lens as the light diameter
`expanding element and a lens as the light collimating
`element are individually formed and are combined into one
`body.
`
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`

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`Patent Application Publication Nov. 18, 2004 Sheet 1 0f 12
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`US 2004/0227998 A1
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`Patent Application Publication Nov. 18, 2004 Sheet 3 0f 12
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`US 2004/0227998 A1
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`Patent Application Publication Nov. 18, 2004 Sheet 4 0f 12
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`US 2004/0227998 A1
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`Patent Application Publication Nov. 18, 2004 Sheet 5 0f 12
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`US 2004/0227998 A1
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`Patent Application Publication Nov. 18, 2004 Sheet 6 0f 12
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`Patent Application Publication Nov. 18, 2004 Sheet 7 0f 12
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`Patent Application Publication Nov. 18, 2004
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`Sheet 8 0f 12
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`US 2004/0227998 A1
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`Patent Application Publication Nov. 18, 2004 Sheet 9 0f 12
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`Patent Application Publication Nov. 18, 2004 Sheet 10 0f 12
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`US 2004/0227998 A1
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`Patent Application Publication Nov. 18, 2004 Sheet 12 0f 12
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`US 2004/0227998 A1
`
`Nov. 18, 2004
`
`LENS, LIGHT IRRADIATION APPARATUS, AND
`LASER POINTER
`
`BACKGROUND OF THE INVENTION
`
`[0001]
`
`1. Field of the Invention
`
`[0002] The present invention relates to a light irradiation
`apparatus and a laser pointer which are provided with a light
`emitting module as a light emitting element to convert a
`wavelength of emitting light, and in particular to a light
`irradiation apparatus and a laser pointer provided with a
`laser light emitting module using a laser diode. Further, the
`present invention relates to a lens suitable for use in those
`light irradiation apparatus and laser pointer.
`
`[0003]
`
`2. Description of the Related Art
`
`In order to point a reference part in a presentation,
`[0004]
`a labeler for construction, a marker for apparels, a marker for
`assemblies and the like, pointers which irradiate a spot light
`are used. Those pointers have specific characteristics
`capable of pointing even from a position distant from a
`pointing object to some extent, because those pointers point
`at a relevant portion by using light, and also capable of being
`handled easily, because those pointers are smaller than
`rod-type pointing apparatuses. In order for a user to point an
`aimed area regardless of distance to an object irradiated with
`light, light projected from a pointer needs to be approxi-
`mately collimated light and laser light is suitable to be used.
`
`[0005] Further, in order to point the area aimed by the user
`and also to improve visibility with respect to the pointed
`area, laser light emitted from the light source, the diameter
`of which can be expanded to be irradiated onto a certain
`area, is required, and a pointer capable of projecting laser
`light, which is approximately collimated and has an
`expanded diameter, has been desired.
`
`laser light which is
`in order to project
`[0006] Thus,
`approximately collimated and has an expanded diameter,
`there is required a lens having multiple functions such as
`expanding the diameter of laser light projected from the light
`source and making the laser light approximately collimated.
`
`[0007] Conventionally, a lens having multiple functions
`has been formed by combining with high accuracy a plu-
`rality of lenses which have individual functions respectively,
`and a combined lens is well known, in which for example
`each lens is joined with adhesive or the like while perform-
`ing a positioning so as to eliminate eccentricity, discrepancy
`of light axes, and an error in gap of surfaces between the
`plurality of lenses (refer to, for example, patent reference 1).
`
`[0008]
`
`[Patent Reference 1]
`
`Japanese
`[0009]
`10-123388
`
`Laid-open Patent Application No.
`
`[0010] However, although complicated and highly precise
`processing has become possible with the progress in mold-
`ing technology, there has been a problem that a yield rate
`becomes low when manufacturing a lens having multiple
`functions as described above, because there is a case where
`a positioning error of lenses, that is eccentricity, discrepancy
`of light axes, and an uneven gap of lens surfaces occur at the
`time of combining the plurality of lenses which are indi-
`vidually formed.
`
`it is
`In addition, in order to improve yield rate,
`[0011]
`possible to increase a positioning accuracy of manufacturing
`apparatus to combine the plurality of lenses; however, the
`manufacturing process of combining the plurality of lenses
`becomes complicated and at the same time, it also leads to
`an increase in manufacturing cost.
`
`[0012] Further, it is also possible to improve a processing
`accuracy of respective lenses which are combined and to add
`a mechanism of adjusting the eccentricity, the discrepancy of
`light axes, the uneven gap of lens surfaces and the like to a
`lens holder in which those lenses are accommodated, how-
`ever it causes an increase in manufacturing cost of the lens
`to be combined, an increase in number of parts, and an
`increase in processing cost.
`
`[0013] Moreover, incident light which enters a combined
`lens composed of a plurality of lenses is affected by errors
`caused by the eccentricity, the discrepancy of light axes and
`the uneven gap of lens surfaces whenever entering respec-
`tive lenses, and it has been difficult to accurately expand the
`diameter of incident light to be projected as approximately
`collimated light.
`
`[0014] Accordingly, it is an object of the present invention
`to provide a lens, in which eccentricity, discrepancy of light
`axes, uneven gap of lens surfaces, and the like can be
`reduced without performing the positioning of respective
`lenses and there is no increase in manufacturing cost of a
`lens having multiple functions, and to provide a light irra-
`diation apparatus and a laser pointer to which the lens is
`applied.
`
`SUMMARY OF THE INVENTION
`
`[0015] A lens according to the present invention includes:
`a light diameter expanding means for expanding a diameter
`of incident light to be projected; a light collimating means
`for receiving the light having its diameter expanded by the
`above light diameter expanding means to project approxi-
`mately collimated light; and a lens unit in which the above
`described light diameter expanding means and light colli-
`mating means are integrally formed. According to the lens of
`the present invention, since the light diameter expanding
`means and the light collimating means are not separately
`prepared to be combined into one body, it is possible to
`control occurrence of eccentricity, discrepancy of light axes,
`and error in gap of lens surfaces due to a positioning
`discrepancy between the light diameter expanding means
`and the light collimating means, and it is possible to provide
`an integrally formed lens having two functions such as
`expanding the diameter of light and collimating light. More-
`over, in comparison to a case in which a lens having the light
`diameter expanding means and a lens having the light
`collimating means are joined with adhesive to form one
`body while adjusting with high accuracy relative positions
`thereof, a manufacturing process can be simplified, which
`also leads to reduction in manufacturing cost. Further, the
`number of parts can be reduced, because the diameter of
`incident light is expanded to project approximately colli-
`mated light using one piece of lens.
`
`In the lens according to the present invention, at
`[0016]
`least either of the above described light diameter expanding
`means and light collimating means may be formed by
`processing a lens unit so as to have predetermined curva-
`tures on light incident side and on light emitting side of the
`
`14
`
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`

`

`US 2004/0227998 A1
`
`Nov. 18, 2004
`
`above described lens unit, respectively. According to such
`lens, by forming the light diameter expanding means on the
`light incident side of the lens unit in advance and further
`forming the light collimating means on the light emitting
`side,
`it
`is possible for one piece of lens to expand the
`diameter of light to be collimated and emitted as the approxi-
`mately collimated light.
`
`[0017] Further, in such lens, the above described prede-
`termined curvatures may be adjusted so that a focal point of
`the above described light diameter expanding means and a
`focal point of the above described light collimating means
`can be set to the approximately same point. In such lens,
`dispersion in refractive indexes of the light diameter expand-
`ing means and the light collimating means is rarely
`observed, because the light diameter expanding means and
`the light collimating means are formed with the same
`material. Accordingly, it is possible to accurately expand the
`diameter of incident light and to emit approximately colli-
`mated light only by adjusting the respective curvatures of
`the light diameter expanding means and the light collimating
`means.
`
`In the lens according to the present invention, the
`[0018]
`above described light diameter expanding means can be a
`concave lens and the above described light collimating
`means can be a convex lens, for example. According to such
`lens, it is possible to expand the diameter of light using the
`concave lens to emit approximately collimated light using
`the convex lens, so that approximately collimated light, the
`diameter of which is expanded compared to the incident
`light, can be emitted using one piece of lens. Moreover, by
`forming the concave lens and the convex lens, distance
`between lens surfaces can be made shorter in comparison to
`a case in which two pieces of convex lens are formed, and
`the whole lens can be small-sized.
`
`[0019] Further, in the lens according to the present inven-
`tion, the above described light diameter expanding means
`can be a convex lens and also the above described light
`collimating means can be a convex lens, for example.
`According to such lens, the light path of incident light is
`intersected by the convex lens to expand the diameter of
`light and the light having the expanded light path can be
`emitted as approximately collimated light by the convex
`lens. Moreover, when a polishing process is required, a
`convex lens can be formed easily in comparison to a concave
`lens and therefore, it is possible to simplify a manufacturing
`process and to reduce manufacturing costs.
`
`[0020] Furthermore, in the lens according to the present
`invention, the above described lens unit may be provided
`with a light reflection preventing means for reducing dif-
`fused reflection of light, the diameter of which is expanded
`by the above described light diameter expanding means. By
`reducing the diffused reflection of the incident light passing
`through the lens using such light reflection preventing
`means, it becomes possible to control a distribution range of
`light intensity when approximately collimated light emitted
`from the lens is irradiated on an object. Accordingly, vis-
`ibility can be enhanced without having an irradiated area
`blurred.
`
`In such lens, the above described light reflection
`[0021]
`preventing means may be a light absorption member.
`According to such light absorption member, reflection of
`light can be reduced and a distribution range of light
`
`intensity can be reduced by absorbing the light which is the
`cause of expanding the distribution range of light intensity.
`
`the above described light
`in such lens,
`[0022] Further,
`absorption member can be formed on a circumferential
`surface of the above described lens unit and on the incident
`
`side of the lens unit where the above incident light enters the
`above lens unit. According to such light absorption member,
`it is possible to reduce the reflection of light in the lens unit
`and it is possible to irradiate approximately collimated light
`even onto a distant object by projecting the approximately
`collimated light, the diameter of which expanded.
`
`In the lens according to the present invention, the
`[0023]
`above described lens unit may include an optical filter to
`select a wavelength of the above described light. According
`to such optical filter, it is possible to select the wavelength
`of light emitted from the lens as approximately collimated
`light, and the light having a required wavelength can be
`irradiated on an object.
`
`In such lens, the above described optical filter also
`[0024]
`can shield infrared light. According to such optical filter,
`only visible light can be emitted as approximately colli-
`mated light from the lens by shielding unnecessary infrared
`light which is invisible, and it is possible to irradiate light of
`high safety without disposing a filter separately.
`
`In the lens according to the present invention, the
`[0025]
`above described incident light may be approximately colli-
`mated light. According to such lens, it is possible to expand
`the diameter of approximately collimated light emitted from
`a light source to be emitted as approximately collimated
`light having a larger diameter.
`
`In such lens, the above described approximately
`[0026]
`collimated light may be laser light. According to such lens,
`it is possible to emit the laser light that is coherent light
`having the diameter thereof expanded as approximately
`collimated light and an object to which the approximately
`collimated light is irradiated can be illuminated with light of
`predetermined color.
`
`irradiation apparatus according to the
`[0027] A light
`present invention includes: a light emitting means for emit-
`ting light; a light diameter expanding means for expanding
`the diameter of light emitted from the above described light
`emitting means to be emitted; a light collimating means for
`receiving the incident
`light,
`the diameter of which is
`expanded by the above described light diameter expanding
`means and emitting approximately collimated light; and a
`lens having a lens unit in which the above described light
`diameter expanding means and light collimating means are
`integrally formed. According to such light irradiation appa-
`ratus, it is possible to collimate and emit light having the
`diameter
`thereof expanded. Further,
`the light diameter
`expanding means and the light collimating means are inte-
`grally formed in the lens unit, so that it
`is possible to
`simplify a manufacturing process of the light irradiation
`apparatus in comparison to a case where the light diameter
`expanding means and the light collimating means are indi-
`vidually formed to be combined, which also leads to reduc-
`tion in manufacturing costs.
`
`the
`irradiation apparatus,
`in such light
`[0028] Further,
`above described light projecting means can be a laser light
`emitting module which projects laser light. According to
`such light irradiation apparatus, it is possible to expand the
`15
`
`15
`
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`

`US 2004/0227998 A1
`
`Nov. 18, 2004
`
`diameter of laser light projected from the laser light emitting
`module to be projected as approximately collimated light.
`
`in such light irradiation apparatus,
`[0029] Furthermore,
`the above described laser emitting module may includes: a
`solid-state laser medium; a non-linear optical element which
`converts a wavelength of light emitted from the above
`solid-state laser medium; a resonator consisting of a pair of
`resonance reflective portions between which the above
`described solid-state laser medium and non-linear optical
`element are held so as to make light back and forth; a laser
`diode which emits light to excite the above solid-state laser
`medium; and a window cap in which a window portion is
`formed to take out
`the light projected from the above
`described resonator, and the above described resonator and
`the above described laser diode are accommodated. Accord-
`
`ing to such light irradiation apparatus, a group of elements
`for emitting laser light is accommodated in the window cap,
`so that dust is prevented from adhering to the laser diode or
`the resonator. Accordingly, handling becomes easy when
`mounting the laser light emitting module on electronic
`equipment and further,
`it becomes possible to attain an
`improvement in reliability of the laser light emitting module
`and longer operating life thereof. In addition, an airtight
`member, which transmits light and maintains air-tightness, is
`attached to the window portion and the air-tightness is
`maintained inside the window cap, so that dustproof effect
`can be further enhanced.
`
`irradiation apparatus according to the
`[0030] The light
`present invention may include a lens holder to accommodate
`the above described lens, and the above lens holder can be
`provided with a light reflection preventing means for reduc-
`ing diffused reflection of light projected from the above
`described light diameter expanding means. According to
`such lens holder, by reducing the diffused reflection when
`incident light passes through the lens, a distribution range of
`light intensity can be reduced when approximately colli-
`mated light projected from the lens is irradiated on an object,
`so that the visibility is enhanced.
`
`[0031] According to such light irradiation apparatus, the
`above described light reflection preventing means can be a
`light absorption member which is formed inside the above
`described lens holder. According to such lens holder, it is
`possible to eliminate light causing expansion of a distribu-
`tion range of light intensity of approximately collimated
`light projected from the lens. Accordingly, it becomes pos-
`sible to irradiate the approximately collimated light even on
`a distant object.
`
`[0032] Further, in the above light irradiation apparatus, by
`adjusting an area, which the above described light absorp-
`tion member covers, of a circumferential surface of the
`above described lens unit, the light intensity distribution of
`light projected from the above described lens can be
`adjusted. According to such light irradiation apparatus, an
`amount of light to be absorbed into the light absorption
`member can be adjusted, and the light intensity distribution
`on an object which is irradiated by the light projected from
`the light irradiation apparatus can be adjusted.
`
`[0033] Moreover, in the light irradiation apparatus accord-
`ing to the present invention, by adjusting an area of the
`above described window portion, the light intensity distri-
`bution of light projected from the above described lens can
`be adjusted. According to such window portion, the light
`
`intensity distribution of incident light which enters the lens
`can be adjusted, and the light intensity distribution on an
`object which is irradiated with the light projected from the
`light irradiation apparatus can be adjusted.
`
`In the light irradiation apparatus according to the
`[0034]
`present invention,
`the above described lens unit can be
`provided with an optical filter which selects a wavelength of
`light projected from the above described window portion.
`According to such optical filter, a wavelength of light
`projected as approximately collimated light from the lens
`can be selected, and light having a required wavelength can
`be irradiated on an object.
`
`the above
`irradiation apparatus,
`In such light
`[0035]
`described optical filter can also shield infrared light. Accord-
`ing to such optical filter, only visible light can be projected
`as approximately collimated light from the lens thereof by
`shielding unnecessary infrared light which is invisible, and
`it becomes possible to irradiate light of high safety without
`disposing a filter separately.
`
`[0036] A laser pointer according to the present invention
`has: a laser light emitting module which includes a solid-
`state laser medium, a non-linear optical element to convert
`a wavelength of light emitted from the solid-state laser
`medium, a resonator consisting of a pair of resonance
`reflective portions between which the solid-state laser
`medium and the non-linear optical element are held so as to
`make light back and forth, a laser diode to emit light so as
`to excite the solid-state laser medium, and a window cap in
`which a window portion is formed to take out light projected
`from the above resonator, and the above resonator and the
`above laser diode are accommodated; and a lens which
`expands the diameter of light projected from the above
`window portion so as to make approximately collimated
`light. The above described lens has: a light diameter expand-
`ing means for expanding the diameter of light projected
`from the above window portion to be projected; a light
`collimating means for receiving the incident light the diam-
`eter of which is expanded by the light diameter expanding
`means and projecting approximately collimated light; and a
`lens unit
`in which the above described light diameter
`expanding means and light collimating means are integrally
`formed. According to such laser pointer, a group of elements
`to emit laser light is accommodated in the window cap, so
`that dust can be prevented from adhering to the laser diode
`or the resonator. Therefore, handling becomes easy when
`mounting the laser light emitting module on electronic
`equipment, and further
`it becomes possible to attain
`improvement in reliability of the laser light emitting module
`and longer operating life thereof. In addition,
`it becomes
`possible to further enhance a dustproof effect by attaching to
`the window portion an airtight member which transmits light
`and maintains an air-tightness so as to maintain the air-
`tightness inside the window cap. Moreover, by using a lens
`in which the light diameter expanding means and the light
`collimating means are integrally formed,
`it is possible to
`simplify a manufacturing process of the laser pointer, and
`manufacturing cost thereof can be reduced.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0037] FIGS. 1A and 1B are diagrams showing an outer
`appearance of a lens according to a first embodiment of the
`present invention, in which FIG. 1A is a rear view showing
`16
`
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`

`

`US 2004/0227998 A1
`
`Nov. 18, 2004
`
`the lens from the side where an incident light enters and
`FIG. 1B is a lateral view showing the side of the lens;
`
`pointer is explained as an example of a light irradiation
`apparatus to which the present invention is applied.
`
`[0038] FIG. 2 is a diagram explaining a light path in
`which the diameter of incident light is expanded by the lens
`to be projected as approximately collimated light;
`
`[0039] FIGS. 3A and 3B are diagrams showing an outer
`appearance of a lens according to a second embodiment of
`the present invention, in which FIG. 3A is a rear view
`showing the lens from the side where incident light enters
`and FIG. 3B is a lateral view showing the side of the lens;
`
`[0040] FIG. 4 is a diagram explaining a light path in
`which the diameter of incident light is expanded by the lens
`to be projected as approximately collimated light;
`
`[0041] FIGS. 5A and 5B are diagrams showing an outer
`appearance of a lens according to a third embodiment of the
`present invention, in which FIG. 5A is a rear view showing
`the lens from the side where incident light enters and FIG.
`5B is a lateral view showing the side of the lens;
`
`[0042] FIGS. 6A and 6B are diagrams showing another
`example of an outer appearance of the lens according to the
`third embodiment, in which FIG. 6A is a rear view showing
`the lens from the side where incident light enters and FIG.
`6B is a lateral view showing the side of the lens;
`
`[0043] FIG. 7 is a light intensity distribution diagram
`showing the result of an experiment which is performed
`using the lens, in which light intensity distributions of a lens
`with black coating and a lens without black coating are
`compared;
`
`[0044] FIG. 8 is a cross-sectional diagram showing a
`structure of a laser pointer which is an example of a light
`irradiation apparatus according to a fourth embodiment of
`the present invention;
`
`[0045] FIG. 9 is an exploded perspective view showing
`the structure of the laser pointer which is an example of the
`light irradiation apparatus;
`
`[0046] FIG. 10 is an exploded perspective view showing
`a state in which a lens is removed from a lens holder;
`
`[0047] FIG. 11 is a cross-sectional diagram showing a
`structure of a laser light emitting module;
`
`[0048] FIG. 12 is an exploded perspective view showing
`the structure of the laser light emitting module;
`
`[0049] FIG. 13 is a schematic diagram to explain conver-
`sion of a wavelength of light performed in the laser light
`emitting module by SHG with indicating a wavelength in
`each part;
`
`[0050] FIG. 14 is a schematic diagram showing a light
`path in the laser light emitting module; and
`
`[0051] FIG. 15 is an exploded perspective view showing
`a structure of a driver portion.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`[0052] Hereinafter, detailed explanations are made with
`respect to a lens, a light irradiation apparatus, and a laser
`pointer according to the present invention by referring to the
`accompanied drawings. First,
`the lens according to the
`present
`invention is explained and successively, a laser
`
`First Embodiment
`
`[0053] A lens according to the first embodiment of the
`present
`invention includes:
`a light diameter expanding
`means for expanding the diameter of incident light to be
`projected; a light collimating means for receiving incident
`light the diameter of which is expanded by the light diameter
`expanding means to project approximately collimated light;
`and a lens unit in which the light diameter expanding means
`and the light collimating means are integrally formed; and
`the lens has a concave lens portion as the light diameter
`expanding means and a convex lens portion as the light
`collimating means.
`
`[0054] FIG. 1 is a schematic view showing a structure of
`a lens according to the embodiment, wherein FIG. 1A is a
`rear view showing a lens 1 from the side where incident light
`enters and FIG. 1B is a lateral view showing the side of lens
`1. As shown in FIGS. 1A and 1B, the lens 1 is composed
`of a lens unit 2, a concave lens portion 3 and a convex lens
`portion 4, and has an approximately cylindrical shape.
`
`[0055] The concave lens portion 3 is formed on the
`incident side where the incident light enters the lens 1. The
`concave lens portion 3 is a concave lens directly formed in
`the lens unit 2 and constitutes the lens 1 integrally formed
`with the lens unit 2 and the convex lens 4. Accordingly, it is
`possible to simplify a manufacturing process of producing a
`concave lens and a convex lens in comparison to a case in
`which a lens is formed by joining individually produced
`concave lens and convex lens to be combined into one body
`with adhesive. Further,
`it
`is possible to reduce joining
`surfaces, where the concave lens and the convex lens are
`joined with adhesive, with forming the concave lens portion
`3 and the convex lens portion 4 in the lens unit 2. In other
`words, it becomes possible to reduce reflection of light at
`those joined surfaces and to efficiently project the incident
`light entered the lens 1. For example, in case that an optical
`system is composed of two pieces of lens, boundary surfaces
`of respective lenses to the outside are to be four surfaces;
`however, the boundary surfaces can be two by integrally
`forming a concave lens and a convex lens, so that loss
`caused by the reflection of light on the surface of the lens can
`be reduced. Furthermore, since a manufacturing process is
`unnecessary in which individually produced concave lens
`and convex lens are combined into one body while perform-
`ing a positioning thereof, it is also possible to form one piece
`of lens 1 having respective functions of a concave lens and
`a convex lens without requiring an adjustment with high
`accuracy of eccentricity, discrepancy of light axes, and an
`uneven gap of lens surfaces between the concave lens and
`the convex lens.
`
`[0056] The concave lens portion 3 is formed in an end
`surface 5 of the lens unit 2 to have a predetermined curvature
`by a processing method conventionally used when process-
`ing an optical lens. Further, when organic polymer material
`such as glass or plastic is used as an optical material
`constituting the lens 1, it is possible to form the lens 1 with
`high accuracy, in which the concave lens portion 3 and the
`convex lens portion 4 are integrally formed by high-preci-
`sion processing of a mold for forming the optical material
`into the shape of lens and by management of molding
`17
`
`17
`
`

`

`US 2004/0227998 A1
`
`Nov. 18, 2004
`
`conditions. Accordingly, when a concave lens and a convex
`lens are produced very accurately, it is possible to reduce
`eccentricity, discrepancy of light axes, and uneven gap of
`lens surfaces which occur in case of forming a lens by
`combining those lenses to become one body. Further,
`according to the lens 1 in which the concave lens portion 3
`and the convex lens portion 4 are formed integrally in the
`lens unit 2, it is unnecessary to individually adjust a curva-
`ture of each lens in response to dispersion in refractive index
`of the concave lens and the convex lens which are formed
`
`individually.
`
`[0057] Moreover, the lens 1 can also be provided with an
`optical filter which absorbs light of a specific wavelength.
`By using a material which absorbs the light of specific
`wavelength as the material to form the lens 1, it is possible
`to project
`light having the light of specific wavelength
`removed as approximately collimated light from the lens 1.
`Particularly, by forming the lens 1 with a material used in an
`IR cut filter to remove infrared rays (IR) or the like, infrared
`light projected from a later described SHG laser light
`emitting module consisting of a laser diode, a solid-state
`laser, and a non-linear element can be absorbed. Accord-
`ingly, unnecessary infrared laser light which is invisible and
`unrecognizable can be removed by the lens 1 and safety can
`be secured without disposing the IR cut filter separately.
`Furthermore, it is also possible not to project the light of
`specific wavelength by coating at least either of the concave
`lens portion 3 and the convex lens portion 4 with the
`material which absorbs or does not
`transmit
`the above
`
`described light of the specific wavelength.
`
`[0058] The concave lens portion 3 is formed approxi-
`mately in the center of the end surface 5 such that in the lens
`unit 2 a light axis of the concave lens portion 3 and a light
`axis of the convex lens portion