Detection of configuration changes of an optical element in an illumination system

• US 8,592,739 B2
• Filed: 11/02/2010
• Issued: 11/26/2013
• Est. Priority Date: 11/02/2010
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: McEldowney, Scott, Yee, Dawson
• Primary Examiner(s): Legasse, Jr., Francis M
• Application Number:
  US12/938,254
• Publication Number:
  US 20120104225A1
• Time in Patent Office: 1,120 Days
• Field of Search: 250/201.1, 250/201.2, 250/201.3, 250/206, 250/206.1, 250/206.3, 348/294, 348/302, 257/431
• US Class Current: 250/206
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01J 1/0228 Control of working procedures; Failure detection; Spectral bandwidth calculation
• CPC Class Codes: G01J 1/32 adapted for automatic variation of the measured or reference value regulation of light intensity G05D25/00

Abstract

Technology for detecting a change in a configuration position of one or more elements in an illumination system is described. A light source generates an illumination signal, and an element of the system directs a portion of the light of the signal back to a light detector. In one example, the portion of light is reflected back to the light detector. By monitoring an output signal of the light detector based on the directed light, control circuitry can detect that a position of an element of the system has changed. In one example, an off-the-shelf integrated circuit laser diode package including a monitor photodiode can be used with a reflective element. In one example, the reflective element is a tilted optical element. Changes can be detected in the configuration of one or more optical elements of the illumination system which are outside the laser diode package.

Claims

1. An illumination system comprising:

a light source for generating an illumination signal;

one or more optical elements aligned to direct a portion of light of the illumination signal;

a light detector positioned to receive light directed from the

one or more optical elements and the light detector generates an output signal based on the light directed from the optical element; and

control circuitry connected to monitor the output signal of the light detector for detection of a change in a configuration position of one or more elements of the illumination system indicating one of the group consisting of;

an optical element of the one or more elements has been removed;

an optical element of the one or more elements has been damaged;

an optical element of the one or more elements has been

repositioned to cause a non-negligible effect;

a structural element of the one or more elements has been removed;

or

a structural element of the one or more elements has been damaged.

2. The system of claim 1, wherein:

the light source is a laser and the light detector is a photodiode.

3. The system of claim 1, wherein:

the light source is a light emitting diode.

4. The system of claim 1, wherein:

the optical element has a reflective area on a surface of an interior side of a structure supporting the illumination system for directing the portion of light of the illumination signal to the light detector.

5. The system of claim 1, wherein:

the optical element is a diffractive optical element, and the light directed from the diffractive optical element is surface reflected back to the light detector.

6. The system of claim 1, further comprising:

the control circuitry being connected to the light source for turning off the light source responsive to the change in the configuration position of one or more elements of the illumination system.

7. The system of claim 1, wherein:

the one or more optical elements aligned to direct a portion of light of the illumination signal comprises an optical element for collimating the illumination signal and a tilted optical element for reflecting a portion of light of the collimated illumination signal.

8. The system of claim 7, wherein:

the tilted optical element has a tilt angle of less than three degrees with respect to an axis perpendicular to a direction of propagation of the illumination signal.

9. A method for detecting a change in a configuration position of one or more elements in an illumination system comprising:

a light source generating an illumination signal;

reflecting a portion of light of the illumination signal by a tilted optical element of the illumination system to a light detector;

control circuitry monitoring light received at the light detector for detecting a change in the configuration position of one or more elements in the illumination system further comprising

the light detector generating an output signal based on the light received at the light detector, and

the control circuitry detecting the change in the configuration position of one or more elements of the illumination system by monitoring the output signal as an indicator for a change in the light received at the light detector satisfying shut down criteria; and

the control circuitry modifying operation of the illumination system responsive to detecting the change in the configuration position of the one or more elements further comprising

the control circuitry turning off the light source responsive to satisfaction of shut down criteria.

10. An illumination system comprising:

an integrated circuit light source package comprising within the package a light source for generating an illumination signal and a light detector;

an outer structural element of the illumination system for supporting the integrated circuit light source package and one or more optical elements located outside the package, including a reflective element for reflecting a portion of light of the illumination signal, the reflective element further comprising a tilted optical element aligned with a collimating optical element to receive the illumination signal collimated;

the light detector being positioned to receive light reflected back from the reflective element located outside the integrated circuit light source package;

the light detector generates an output signal based on the light reflected back from the reflective element; and

control circuitry communicatively coupled to the light detector for monitoring the output signal of the light detector to determine whether there has been a change in the configuration position of the one or more optical elements outside the integrated circuit light source package.

11. The system of claim 10, wherein the reflective element is a diffractive element.

12. The system of claim 10, wherein the change in the configuration position is indicated by a change of twenty-five percent or more in the output signal.

13. The system of claim 10, wherein:

the control circuitry is connected to the integrated light source package for decreasing the illumination signal of the light source responsive to the output signal indicating there has been a change in the configuration position of the one or more optical elements outside the integrated light source package.

14. The system of claim 10, wherein:

the control circuitry is connected to the integrated light source package for turning off the light source responsive to the output signal indicating there has been a change in the configuration position of the one or more optical elements outside the integrated light source package.

15. The system of claim 10, wherein:

the integrated circuit light source package is an off-the-shelf

integrated circuit laser package wherein

the light source is a laser and the laser also generates a reverse illumination signal;

the light detector is a monitor photodiode which is positioned to receive the reverse illumination signal; and

the output signal represents the light reflected back from the reflective element outside the package and the reverse illumination signal.