LASER PROJECTOR WITH TWO LASER DIODES

Abstract

A device for laser projection comprises a first laser diode configured to emit a first linearly polarized laser beam extending along a first polarization axis and a second laser diode configured to emit a second linearly polarized laser beam extending along a second polarization axis that is perpendicular to the first polarization axis. A polarization combiner is configured to combine the first and second linearly polarizing laser beams into a combined laser beam, wherein the combined laser beam comprises one of: (1) circular polarization; and (2) elliptical polarization. A measuring device is configured to measure an intensity of the combined laser beam. A control unit is configured to receive the measured intensity of the combined laser beam and is further configured to adjust an intensity of at least one of: (1) the first laser diode; and (2) the second laser diode.

Claims

1. A device for laser projection comprising: a first laser diode configured to emit a first linearly polarized laser beam extending along a first polarization axis; a second laser diode configured to emit a second linearly polarized laser beam extending along a second polarization axis that is perpendicular to the first polarization axis, wherein the first and second laser diodes are configured with a same wavelength; a polarization combiner configured to combine the first and second linearly polarizing laser beams into a combined laser beam, wherein the combined laser beam comprises one of: (1) circular polarization; and (2) elliptical polarization; a measuring device configured to measure an intensity of the combined laser beam; and a control unit configured to receive the measured intensity of the combined laser beam and further configured to adjust an intensity of at least one of: (1) the first laser diode; and (2) the second laser diode.

2. The device according to claim 1, wherein the control unit is configured to adjust the intensity of the at least one of the first laser diode and the second laser diode in response to the received measured intensity of the combined laser beam.

3. The device according to claim 1, further comprising a first operating mode wherein the control unit is configured to increase power of the at least one of the first laser diode and the second laser diode as the intensity of the combined laser beam attenuates.

4. The device according to claim 1, Wherein the control unit regulates the intensity of the combined laser beam to a setpoint.

5. The device according to claim 3, further comprising a second operating mode, wherein in the second operating mode the power of the combined laser beam is adjusted for sections of a figure to be projected.

6. The device according to claim 5, wherein the second operating mode is configured to display contours to be projected with differing brightness.

7. The device according to claim 1, wherein the control unit does not exceed a predetermined maximum permissible laser power.

8. The device according to claim 1, wherein the first and second laser diodes are configured to be controlled by pulse width modulation.

9. The device according to claim 1, wherein the first and second laser diodes are configured to be controlled by continuous controlling.

10. The device according to claim 1, further comprising an adjustable focusing apparatus for each of the first and second laser diode.

11. The device according to claim 1, wherein the first laser diode is configured to mount to a first support plate and the second laser diode is configured to mount to a second support plate, wherein the first support plate and the second support plate are attached to a common base support.

12. The device according to claim 11, wherein a first support plate defines a slot configured to enable alignment of the first support plate relative to the second support plate.

13. The device according to claim 1, wherein the combined laser beam is redirected by two galvanometer mirrors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention will be further explained with reference to an exemplary embodiment. In the figures:

[0020] FIG. 1 illustrates a perspective view of an embodiment of two laser diodes that are combined into one superimposed beam; and

[0021] FIG. 2 schematically illustrates an embodiment of the principle of beam combination with polarization.

DETAILED DESCRIPTION OF THE INVENTION

[0022] FIG. 1 shows the configuration of a laser projector 10 with two laser diodes 12, 14. The laser beams of the laser diodes 12, 14 each pass through a focusing optical system 16, 18. The focusing optical system 16, 18 is adjusted at a distance from the projection surface. The laser beam 20 of the laser diode 12 strikes a mirror 22 and is redirected toward the polarization combiner 24. The laser beam 28 that has passed through the focusing unit 18 also strikes the polarization combiner 24 and also contributes to the combined laser beam 26. The measuring arrangement or measuring device 25 for the intensity of the combined laser beam is arranged at the height of the polarization combiner 24 and measures the “waste” light of the beam 20 that is not redirected toward the combined laser beam 26, and the redirected light of the beam 28 that is deflected in the polarization combiner 24. The measuring arrangement 25 can be a photodiode that is sensitive to the wavelength of the laser light.

[0023] FIG. 2 shows the principle mode of operation of the polarization combiner 24. The incoming beam 20 is polarized linearly with a so-called s-polarization. The also incoming beam 28 also possesses a linear polarization with a p-polarization. S- and p-polarization are perpendicular to each other. The combined light beam 26 possesses a superimposed polarization that appears as a circular or elliptical polarization.

[0024] The polarization combiner is preferably equipped with a measuring apparatus that detects the intensity of the combined laser beam 26. The detected intensity is forwarded to a control unit 50 that is schematically depicted in FIG. 1. The control unit 50 controls the laser diodes 12 and 14. In this case, a distinction is to be made between different operating modes: Both laser diodes 12, 14 possess the same wavelength and can replace each other. If the laser projector is working with one of the laser diodes, for example the laser diode 14, and if its brightness for the projected figure attenuates, a manual switch can therefore be made to the control unit 50 for the other laser diode number 12. The control unit 50 executes the manual switchover in this embodiment. In an automated embodiment, the control unit 50 automatically switches to the other laser diode as the intensity of the combined laser beam attenuates, depending on the attached input signal. In this case, the user does not have to intervene, and the operation of the laser projector continues automatically.

[0025] The control unit 50 can be equipped with a second operating mode. The second operating mode does not necessarily exclude the first operating mode. The second operating mode makes it possible to increase the brightness of the projection in projection points and regions. To accomplish this, the intensity of the combined laser beam is increased. It is particularly advantageous in this context that a user who for example is being guided through the projection with respect to his work steps is thereby given the opportunity of emphasizing individual work steps in the context of the workflow. Moreover, other emphases can also emphasize individual contours more brightly, for example when projecting more than one contour. This increases the clarity when using the laser projector.

LIST OF REFERENCE SIGNS

[0026] 10 Laser projector
12 Laser diode
14 Laser diode
16 Focusing optical system
18 Focusing optical system
20 Laser beam

22 Mirror

[0027] 24 Polarization combiner
25 Measuring arrangement
26 Combined laser beam
28 Laser beam
50 Control unit