Apparatus for projecting a line of light from a diode-laser array

• US 6,773,142 B2
• Filed: 01/07/2002
• Issued: 08/10/2004
• Est. Priority Date: 01/07/2002
• Status: Expired due to Fees

• Current Assignee: Coherent Inc (Coherent Corp.)
• Original Assignee: Coherent Inc (Coherent Corp.)
• Inventors: Rekow, Mathew N.
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): Choi, Jacob Y.
• Application Number:
  US10/043,036
• Publication Number:
  US 20030128543A1
• Time in Patent Office: 946 Days
• Field of Search: 362/259, 362/268, 362/331, 362/335, 235/462.35, 359/621, 359/622, 359/623, 359/668, 359/671, 359/619, 359/628
• US Class Current: 362/259
• CPC Class Codes: G02B 19/0014 at least one surface having optical power
• CPC Class Codes: G02B 19/0057 in the form of a laser diode array, e.g. laser diode bar semiconductor laser arrays with beam combining arrangement H01S5/4012
• CPC Class Codes: G02B 27/09 Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for adapting the beam shape of a laser diode G02B19/0052; adapting the beam shape of an LED G02B19/0061; coupling into light guides using intermediate optical elements G02B6/4204; beam shaping specially adapted for lasers H01S3/005

Abstract

Apparatus for projecting a line of light includes a linear array of diode-lasers arranged in a diode-laser bar. An optical system focuses fast axis diverging rays from diode-lasers in the array into a fast-axis focal plane of the optical system. The optical system forms slow axis rays from the diode-lasers into bundles of parallel rays that intersect in the fast axis focal plane. The focused fast-axis rays and the intersecting bundles of parallel rays form the line of light in the fast axis focal plane. The optical system includes two arrays of cylindrical microlens surfaces. The microlens surfaces contribute to providing a uniform intensity of light along the line of light.

Claims

1. An illumination apparatus for projecting a line of light, comprising;

a plurality of diode-lasers each thereof having an emitting-aperture and arranged in an elongated linear array thereof, said diode-lasers being spaced apart by a spacing defined as the distance between the centers of adjacent ones thereof;

said linear diode-laser array having a slow axis parallel to the length direction thereof, and a fast axis perpendicular to said slow axis, light being emitted from each of said diode-lasers, from an emitting aperture thereof, as diverging rays in both said fast and slow axes, in a general direction of propagation mutually perpendicular to both said fast and slow axes;

an optical system, said optical system including a first anamorphic lens, and a lens group including a second anamorphic lens and a spherical lens having positive optical power, said optical system having a longitudinal axis parallel to the propagation direction of light from said diode-lasers and having mutually perpendicular fast and slow axes corresponding to said fast and slow axes of said diode-lasers;

said optical system further including one or more arrays of microlenses, said one or more arrays of microlenses providing two arrays of cylindrical refracting surfaces and being located between said first anamorphic lens and said lens group, said arrays of cylindrical refracting surfaces having a pitch defined as the distance between vertices of adjacent ones of said cylindrical surfaces, the pitch of said arrays of cylindrical refracting surfaces being different from the spacing between said diode-lasers and said cylindrical refracting surfaces being arranged such that each thereof receives rays from a plurality of said diode-lasers and such that rays leaving said one or more microlens arrays arrive at said lens group as rays diverging in both said fast and slow axes; and

said lens group being arranged to focus said fast-axis diverging rays from said one or more microlens arrays in a focal plane perpendicular to said longitudinal optical axis, and arranged to form said slow axis diverging rays from said one or more microlens arrays into a plurality of converging bundles of parallel rays each thereof including rays from a plurality of diode-lasers, said converging bundles of parallel rays intersecting in said focal plane, whereby light from said diode-lasers is formed into a line of light about in said focal plane, said line of light having a width in said fast axis and a length in said slow axis.

2. The apparatus of claim 1, wherein each of said first and second anamorphic lenses of said optical system has greater optical power in the fast axis than in the slow axis.

3. The apparatus system of claim 2, wherein each of said first and second anamorphic lenses of said optical system has positive optical power in the fast axis and zero optical power in the slow axis.

4. The apparatus system of claim 3, wherein each of said microlenses in said at least one microlens array have zero optical power in the fast axis and positive optical power in the slow axis.

5. The apparatus system of claim 1, wherein there is only one microlens array and each of said microlenses in said microlens array has first and second cylindrical surfaces.

6. The apparatus system of claim 1, wherein there are two microlens arrays and each of said microlenses in said microlens array has a plane first surface and cylindrical second surface.

7. The apparatus system of claim 1, wherein said spherical lens group is a single element lens.

8. The apparatus of claim 1, wherein said spherical lens of said lens group is a multiple element lens.

9. The apparatus of claim 1, wherein said spherical lens of said lens group precedes said second anamorphic lens in the direction of propagation.

10. The apparatus of claim 1, wherein said second anamorphic lens precedes said spherical lens of said lens group in the direction of propagation.

11. The apparatus of claim 1, wherein the pitch of said microlens array is greater than the spacing of diode-lasers in said diode-laser array.

12. The apparatus of claim 1, wherein said arrays of cylindrical refracting surfaces are designated as first and second arrays in the direction of propagation and have equal pitch, said arrays of cylindrical refracting surfaces being further arranged such that each cylindrical refracting surface in said second array thereof forms an image of a corresponding cylindrical refracting surface in said first array thereof at infinity.

13. An illumination apparatus for projecting a line of light, comprising:

a plurality of diode-lasers each thereof having an emitting-aperture and arranged in an elongated linear array thereof, said diode-lasers being spaced apart by a spacing defined as the distance between the centers of adjacent ones thereof;

said linear diode-laser array having a slow axis parallel to the length direction thereof, and a fast axis perpendicular to said slow axis, light being emitted from each of said diode-lasers from an emitting aperture thereof as diverging rays in both said fast and slow axes in a general direction of propagation mutually perpendicular to both said fast and slow axes;

an optical system, said optical system including a first cylindrical lens, and a lens group including a second cylindrical lens and a spherical lens having positive optical power, said optical system having a longitudinal axis parallel to the propagation direction of light from said diode-lasers and having mutually perpendicular fast and slow axes corresponding to said fast and slow axes of said diode-lasers;

said optical system further including an array of microlenses, said array of microlenses providing two arrays of cylindrical refracting surfaces and being located between said first cylindrical lens and said lens group, said arrays of cylindrical refracting surfaces having a pitch defined as the distance between vertices of adjacent ones of said cylindrical surfaces, the pitch of said arrays of cylindrical refracting surfaces being different from the spacing between said diode-lasers and said cylindrical refracting surfaces being arranged such that each thereof receives rays from a plurality of said diode-lasers and such that rays leaving said microlens array arrive at said lens group as rays diverging in both said fast and slow axes; and

said lens group being arranged to focus said fast-axis diverging rays from said microlens array in a focal plane perpendicular to said longitudinal optical axis, and arranged to form said slow axis diverging rays from said microlens array into a plurality of converging bundles of parallel rays each thereof including rays from a plurality of diode-lasers, said converging bundles of parallel rays intersecting in said focal plane, whereby light from said diode-lasers is formed into a line of light about in said focal plane, said line of light having a width in said fast axis and a length in said slow axis.

14. The illumination apparatus of claim 13, wherein said arrays of cylindrical refracting surfaces are designated the first and second arrays numbered in the direction of propagation of light through the illumination apparatus and wherein the pitch of said cylindrical refracting surfaces in each of said arrays thereof is the same and each cylindrical refracting surface in said second array thereof is optically spaced by the focal length of said cylindrical refracting surface from a corresponding cylindrical refracting surface in said first array thereof.

15. An illumination apparatus for projecting a line of light, comprising:

a plurality of diode-lasers each thereof having an emitting-aperture and arranged in an elongated linear array thereof, said diode-lasers being spaced apart by a spacing defined as the distance between the centers of adjacent ones thereof;

said linear diode-laser array having a slow axis parallel to the length direction thereof, and a fast axis perpendicular to said slow axis, light being emitted from each of said diode-lasers from an emitting aperture thereof as diverging rays in both said fast and slow axes in a general direction of propagation mutually perpendicular to both said fast and slow axes;

an optical system, said optical system including a first cylindrical lens, and a lens group including a second cylindrical lens and a spherical lens having positive optical power, said optical system having a longitudinal axis parallel to the propagation direction of light from said diode-lasers and having mutually perpendicular fast and slow axes corresponding to said fast and slow axes of said diode-lasers;

said optical system further including two arrays of plano convex microlenses, providing two arrays of cylindrical refracting surfaces and being located between said first cylindrical lens and said lens group, said arrays of cylindrical refracting surfaces having a pitch defined as the distance between vertices of adjacent ones of said cylindrical surfaces, the pitch of said arrays of cylindrical refracting surfaces being different from the spacing between said diode-lasers and said cylindrical refracting surfaces being arranged such that each thereof receives rays from a plurality of said diode-lasers and such that rays leaving said microlens arrays arrive at said lens group as rays diverging in both said fast and slow axes; and

said lens group being arranged to focus said fast-axis diverging rays from said microlens array in a focal plane perpendicular to said longitudinal optical axis, and arranged to form said slow axis diverging rays from said microlens arrays into a plurality of converging bundles of parallel rays each thereof including rays from a plurality of diode-lasers, said converging bundles of parallel rays intersecting in said focal plane, whereby light from said diode-lasers is formed into a line of light about in said focal plane, said line of light having a width in said fast axis and a length in said slow axis.

16. The illumination apparatus of claim 15, wherein said arrays of cylindrical refracting surfaces are designated the first and second arrays numbered in the direction of propagation of light through the illumination apparatus and wherein of the pitch of said cylindrical refracting surfaces in each of said arrays thereof is the same and each cylindrical refracting surface in said second array thereof is optically spaced by the focal length of said cylindrical refracting surface from a corresponding cylindrical refracting surface in said first array thereof.

17. An illumination apparatus for projecting a line of light, comprising:

a plurality of diode-lasers each thereof having an emitting-aperture and arranged in an elongated linear array thereof, said diode-lasers being spaced apart by a spacing defined as the distance between the centers of adjacent ones thereof;

said linear diode-laser array having a slow axis parallel to the length direction thereof, and a fast axis perpendicular to said slow axis, light being emitted from each of said diode-lasers from an emitting aperture thereof as diverging rays in both said fast and slow axes in a general direction of propagation mutually perpendicular to both said fast and slow axes;

an optical system, said optical system including a first cylindrical lens, and a lens group including a second cylindrical lens and a spherical lens having positive optical power, said optical system having a longitudinal axis parallel to the propagation direction of light from said diode-lasers and having mutually perpendicular fast and slow axes corresponding to said fast and slow axes of said diode-lasers, and said first and second cylindrical lenses having positive optical power in said fast axis and zero optical power in said slow axis;

said optical system further including first and second arrays of cylindrical refracting surfaces located between said first cylindrical lens and said lens group, said arrays being numbered in the direction of propagation of light through the illumination apparatus;

said arrays of cylindrical refracting surfaces having a pitch defined as the distance between vertices of adjacent ones of said cylindrical surfaces, the pitch of each of said arrays of cylindrical refracting surfaces being the same and being different from the spacing between said diode-lasers, each cylindrical refracting surface in said second array thereof being optically spaced by the focal length of said cylindrical refracting surface from a corresponding cylindrical refracting surface in said first array thereof.

said cylindrical refracting surfaces being arranged with respect to said first cylindrical lens such that each thereof receives rays from a plurality of said diode-lasers and such that rays leaving said second array of cylindrical refracting surfaces arrive at said lens group as rays diverging in both said fast and slow axes; and

said lens group being arranged to focus said fast-axis diverging rays from said second array of cylindrical refracting surfaces in a focal plane perpendicular to said longitudinal optical axis, and arranged to form said slow axis diverging rays from said second array of cylindrical refracting surfaces into a plurality of converging bundles of parallel rays each thereof including rays from a plurality of diode-lasers, said converging bundles of parallel rays intersecting in said focal plane, whereby light from said diode-lasers is formed into a line of light about in said focal plane, said line of light having a width in said fast axis and a length in said slow axis.

18. The illumination system of claim 17, wherein said spherical lens precedes said second cylindrical lens in the direction of propagation of light through the illumination apparatus.

19. The illumination system of claim 17, wherein said second cylindrical lens precedes said spherical lens in the direction of propagation of light through the illumination apparatus.