UNIFORMITY ADJUSTMENT METHOD FOR A DIODE-LASER LINE-PROJECTOR

• US 20140085616A1
• Filed: 09/27/2012
• Published: 03/27/2014
• Est. Priority Date: 09/27/2012
• Status: Active Grant

• Current Assignee: Coherent Inc (Coherent Corp.)
• Original Assignee: Coherent Inc (Coherent Corp.)
• Inventors: NACKERUD, Erik, LOUNSBURY, Jimson, KAIN, Patrick
• Granted Patent: US 9,400,391 B2
• Time in Patent Office: Days
• US Class Current: 353/101
• CPC Class Codes: G02B 19/0014 at least one surface having optical power
• CPC Class Codes: G02B 19/0052 the light source comprising a laser diode coupling into light guides using intermediate optical elements G02B6/4204; semiconductor lasers having optical devices external to the laser cavity H01S5/005
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• CPC Class Codes: G02B 27/0955 Lenses lenses per se G02B3/00
• CPC Class Codes: G02B 27/0966 Cylindrical lenses cylindrical lenses per se G02B3/06

Abstract

In a line projector a diode-laser beam having an elliptical cross-section is projected onto a Powell lens which spreads the beam to form a line of light. Distribution of power along the line of light is adjusted by rotating the diode-laser beam with respect to the Powell lens.

Claims

1. A method of manufacturing a diode laser line projector device, said device including a diode laser generating a beam of radiation having orthogonal fast and slow axes, said device including a first lens having an acylindrical surface lying along a first axis, said diode laser and the first lens being mounted and aligned in an elongated housing along the propagation axis of the diode laser beam, said housing permitting the first lens to be rotated about the propagation axis, said method comprising the steps of:

incrementally rotating the first lens about the propagation axis of the beam to vary the azimuthal angle of the first axis of the first lens with respect to the fast and slow axes of the diode laser;

measuring the uniformity of the intensity of the line of light projected by the first lens at various azimuthal angles of the first lens; and

locking the housing to define a fixed azimuthal position between the first axis of the first lens and the axes of the diode laser, said fixed position being based on the measurements.

2. A method as recited in claim 1 wherein the housing is locked in a position that substantially maximizes the intensity uniformity of the projected line of light.

3. A method as recited in claim 1 wherein the step of locking the housing includes tightening one or more set screws mounted to the housing.

4. A method as recited in claim 1 wherein the first axis of the first lens is initially aligned with one of the fast and slow axes of the diode laser and thereafter, the first lens is incrementally rotated to optimize the intensity uniformity.

5. A method as recited in claim 1 wherein said first lens is a Powell lens.

6. A method as recited in claim 1 wherein said device further includes a second lens mounted in the housing and located between the diode laser and the first lens.

7. A method as recited in claim 6 further including the step of adjusting the spacing between the second lens and the diode laser to optimize the output.

8. A method as recited in claim 6 wherein the second lens is a positive lens.

9. A diode laser line projector device comprising:

an elongated housing having first and second sections, said sections being rotatable with to each other along the longitudinal axis of the housing;

a diode laser mounted within the first section of the housing, said diode laser generating a beam of radiation having orthogonal fast and slow axes mutually perpendicular to the axis of rotation of the housing;

a first lens mounted within the second section of the housing, said first lens having an acylindrical surface lying along a first axis perpendicular to the axis of rotation of the housing; and

means for selectively locking the first and second sections of the housing together to prevent rotation after the acylindrical surface of the first lens has been preferentially aligned with respect to the axes of the diode laser.

10. A device as recited in claim 9 wherein said locking means is defined by set screws extending through a wall of the housing.

11. A device as recited in claim 9 wherein said first lens is a Powell lens.

12. A device as recited in claim 9 further including a lens mounted in the housing and positioned between the diode laser and the first lens.

13. A device as recited in claim 12 wherein said housing further includes a means for adjusting the spacing between the second lens and the diode laser.

14. In optical apparatus including a diode laser generating a beam having fast and slow axes perpendicular to each other and perpendicular to the propagation axis thereof, said beam being projected onto an acylindrical lens having orthogonal first and second axes perpendicular to the propagation axis, and which spreads the beam in the first axis to form a line of light having a length in the first axis and a height in the second axis, a method of adjusting of the intensity distribution of the illumination along the length of the line of light, comprising:

selecting an initial alignment of the fast and slow axes of the diode laser beam with the first and second axes of the acylindrical lens;

measuring the distribution of intensity along the length of the line of light; and

if the measured distribution of intensity does not fall within a predetermined desired intensity distribution, incrementally changing the rotational orientation of the fast and slow axes of the diode laser beam with respect to the first and second axes of the acylindrical lens until the measured distribution of intensity falls within the desired intensity distribution and then fixing the rotational orientation of the fast and slow axes of the diode laser beam with the first and second axes of the acylindrical lens.

15. The method of claim 14 wherein the fixed rotational orientation of the fast and slow axes of the diode laser beam with the first and second axes of the acylindrical lens are non-aligned.

16. The method of claim 14 wherein the fixed rotational orientation is selected to maximize the uniformity of the intensity distribution.

17. The method of claim 14 wherein the acylindrical lens is a Powell lens.

18. The method of claim 14 further includes a second lens located between the diode laser and the acylindrical lens.

19. A method as recited in claim 18 further including the step of adjusting the spacing between the second lens and the diode laser to optimize the output.