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

• US 20060176912A1
• Filed: 02/07/2005
• Published: 08/10/2006
• Est. Priority Date: 02/07/2005
• Status: Active Grant

• Current Assignee: Coherent Inc (Coherent Corp.), Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Coherent Inc (Coherent Corp.)
• Inventors: Anikitchev, Serguei G.
• Granted Patent: US 7,355,800 B2
• Time in Patent Office: Days
• US Class Current: 372/9
• 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 27/0966 Cylindrical lenses cylindrical lenses per se G02B3/06
• CPC Class Codes: G02B 27/0994 Fibers, light pipes optical fibers per se G02B6/02
• CPC Class Codes: G02B 6/4218 Optical features
• CPC Class Codes: H01S 5/005 Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping H01S5/026, H01S5/18388 take precedence
• CPC Class Codes: H01S 5/4012 Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence

Abstract

A line-of-light projecting module is illuminated by a diode-laser bar and includes light-pipe for homogenizing light from the diode-laser bar in the slow-axis. A shaping optics assembly directs the light emitted by the diode-laser bar into the entrance end of the light-pipe as a diverging beam in the slow-axis and as a collimated beam in the fast-axis. The light propagates through the light-pipe unguided in the fast axis. The light is guided by the light-pipe in the slow-axis, and homogenized in the slow-axis by making multiple reflections from walls of the light-pipe. An anamorphic projection optics assembly projects the light from the exit end of the light-pipe and focuses the light to form the line-of-light.

Claims

1. Apparatus for projecting a line of light, comprising:

a light-pipe;

at least one diode-laser bar including a plurality of spaced-apart emitters for emitting light, the light from said emitters of said diode-laser bar being emitted in a fast-axis and a slow-axis perpendicular to each other and perpendicular to the general direction of emission;

a first optical arrangement for directing the light emitted by the emitters of said diode-laser bar into said light-pipe, said first optical arrangement and said light-pipe being arranged such that the light propagates through said light-pipe substantially unguided thereby in the fast-axis and guided by said light-pipe in the slow-axis; and

a second optical arrangement arranged to receive light exiting said light-pipe and focus said light to form the line of light.

2. The apparatus of claim 1, wherein the line of light has a length in the slow-axis and a width in the fast-axis.

3. The apparatus of claim 2, wherein the line of light has a length:

width ratio between about 100;

1 and 500;

1.

4. The apparatus of claim 1, wherein the light emitted by said diode-laser bar has a fast-axis divergence and a slow-axis divergence and said first optical arrangement includes a cylindrical lens arranged to collimate light emitted by said diode-laser bar in the fast-axis, and light emitted from said diode-laser bar in the slow-axis is transmitted by the cylindrical lens with divergence thereof unchanged and enters said light-pipe with said first divergence.

5. The apparatus of claim 1, wherein the light emitted by said diode-laser bar has a fast-axis divergence and a slow-axis divergence and said first optical arrangement includes a first cylindrical lens and a second cylindrical lens, said first cylindrical lens being arranged to collimate light emitted by said diode-laser bar in the fast-axis and said second cylindrical lens being arranged to focus said fast-axis collimated light in the slow-axis into said light-pipe.

6. The apparatus of claim 5, wherein said diode-laser bar has a length in the slow-axis and said light-pipe has a slow-axis width less than the length of said diode-laser bar.

7. The apparatus of claim 6, wherein said second cylindrical lens has a slow-axis optical power selected such that the light entering the light-pipe has a slow-axis divergence greater than the second-axis divergence of light emitted from said diode-laser bar.

8. The apparatus of claim 1, wherein the light emitted by said diode-laser bar has a fast-axis divergence and a slow-axis divergence and said first optical arrangement includes first, second, and third cylindrical lenses, said first cylindrical lens being arranged to collimate light emitted by said diode-laser bar in the first axis and said second and third cylindrical lenses being arranged to focus said first-axis collimated light in the slow-axis into said light-pipe.

9. The apparatus of claim 8, wherein said first optical arrangement is a telecentric arrangement in the slow-axis, and light from each emitter of the diode laser bar enters said light-pipe normally with about the same angular spectrum.

10. The apparatus of claim 9, wherein said first, second, and third cylindrical lenses, have respectively first, second, and third focal lengths, and wherein said second lens is spaced apart from said diode-laser bar by about said second focal length, and said second and third lenses are spaced apart by about the sum of said second and third focal lengths.

11. The apparatus of claim 10, wherein said light-pipe has an entrance end spaced apart from said third lens by about said third focal length.

12. The apparatus of claim 10, wherein said first lens is spaced apart from said diode-laser bar by about said first focal length.

13. The apparatus of claim 1, wherein the light emitted by said diode-laser bar has a fast-axis divergence and a slow-axis divergence and said first optical arrangement includes a first cylindrical lens, a lens array including a plurality of second cylindrical lenses, and third and fourth cylindrical lenses, said first cylindrical lens being arranged to collimate light emitted by said diode-laser bar in the fast-axis, each of said second cylindrical lenses being arranged to reduce the divergence of said fast-axis collimated light of a corresponding emitter of said diode-laser bar in the slow-axis and said second and third cylindrical lenses being arranged to focus said fast-axis collimated, slow-axis-divergence-reduced light in the slow-axis into said light-pipe.

14. The apparatus of claim 13, wherein said first optical arrangement is a telecentric arrangement in the slow-axis, and light from each emitter of the diode laser bar enters said light-pipe normally with about the same angular spectrum.

15. The apparatus of claim 14, wherein said fourth cylindrical lens has a focal length less than the focal length of said third lens, and said third and fourth cylindrical lenses are spaced-apart by about the sum of said focal lengths.

16. The apparatus of claim 15, wherein said diode-laser bar has a length in the slow-axis and said light-pipe has a slow-axis width less than the length of said diode-laser bar.

17. The apparatus of claim 1, wherein said second optical arrangement is in the form of an inverse telephoto lens in the slow-axis.

18. The apparatus of claim 1, wherein said light-pipe has first and second ends said second end having first and second faces at an angle to each other, and wherein said light entering said light-pipe at said first end thereof, propagates through said light-pipe to said second end thereof, is reflected through 180 degrees by successive reflections from said first and second faces, and exits said light-pipe at said first end thereof.

19. Apparatus for projecting a line of light, comprising:

at least one diode-laser bar having a length and including a plurality of spaced-apart emitters spaced apart in the length direction, for emitting light, the light from said emitters of said diode-laser bar being emitted in a fast-axis and a slow-axis perpendicular to each other and perpendicular to the general direction of emission;

a light-pipe, said light having a width in said slow-axis less than the length of said diode-laser bar;

a first optical arrangement for directing the light emitted by the emitters of said diode-laser bar into said light-pipe, said first optical arrangement and said light-pipe being arranged such that the light propagates through said light-pipe substantially unguided thereby in the fast-axis and guided by said light-pipe in the slow-axis;

a second optical arrangement arranged to receive light exiting said light-pipe and focus said light to form the line-of-light.

20. The apparatus of claim 19, wherein said light-pipe has a slow-axis width less than or equal to about one-half the width of the diode-laser bar the length of said diode-laser bar.

21. The apparatus of claim 19, wherein said diode-laser bar has a length of about 10.0 mm and said light-pipe has a slow-axis width of about 2.6 mm.

22. The apparatus of claim 19, wherein said first optical arrangement is a telecentric arrangement.

23. The apparatus of claim 22, wherein the light from said emitters of said diode-laser bar is emitted as a diverging beam having a fast-axis divergence and a slow-axis divergence and wherein said first optical arrangement is further arranged such that light entering said light-pipe has a slow-axis divergence greater than the slow-axis divergence of light emitted by said emitters of said diode-laser bar.

24. The apparatus of claim 23, wherein light from each of the emitters in said diode-laser bar enters said-light-pipe normally and with the same angular spectrum of divergence.

25. Apparatus for projecting a line of light, comprising:

at least one diode-laser bar having a length and including a plurality of spaced-apart emitters spaced apart in the length direction, for emitting light, the light from said emitters of said diode-laser bar being emitted as a diverging beam in a fast-axis and a slow-axis perpendicular to each other and perpendicular to the general direction of emission;

a light-pipe;

a first optical arrangement for directing the light emitted by the emitters of said diode-laser bar into said light-pipe, said first optical arrangement and said light-pipe being arranged such that the light propagates through said light-pipe substantially unguided thereby in the fast-axis and guided by said light-pipe in the slow-axis, and said first optical arrangement being also arranged such that light entering said light-pipe has a slow-axis divergence greater than the slow-axis divergence of light emitted by said emitters; and

a second optical arrangement arranged to receive light exiting said light-pipe and focus said light to form the line of light.

26. The apparatus of claim 25, wherein said first optical arrangement is further arranged such that light from each of the emitters in said diode-laser bar enters said-light-pipe normally and with the same angular spectrum of divergence.

27. Apparatus for projecting a line of light, comprising:

at least one diode-laser bar for emitting light the light from said diode-laser bar being emitted in a fast-axis and a slow-axis perpendicular to each other and perpendicular to the general direction of emission, said diode-laser bar having a length in the slow-axis;

a light-pipe having a slow-axis width less than the length of said diode-laser bar;

a first optical arrangement including a slow-axis telecentric relay for directing the light emitted by said diode-laser bar into said light-pipe, said first optical arrangement and said light-pipe being configured and arranged such that the light propagates through said light-pipe substantially unguided thereby in the fast-axis and guided by said light-pipe in the slow-axis; and

a second optical arrangement including an inverse telephoto lens arranged to receive light exiting said light-pipe and focus said light to form the line of light.

28. The apparatus of claim 27, wherein light enters and exits said light-pipe at the same end thereof.