Methods and devices for measuring a concentrated light beam

Abstract

Methods and devices are provided for profiling a beam of light that includes a wavelength λ. The beam of light is received. Secondary light is generated at a wavelength λ′ different from wavelength λ by fluorescing a material with the received beam of light. The secondary light is separated from the received beam of light. The separated secondary light is optically directed to a sensor.

1 . A method for profiling a beam of light that includes a wavelength λ, the method comprising:
 rotating a disk about a central axis of the disk, wherein the disk includes a series of discrete fluorescent dots disposed in a spiral pattern around the disk;   directing a beam of light with a wavelength λ toward the rotating disc, such that the beam of light is incident on the disk along a path substantially parallel with the central axis of the disk;   separating secondary light from the received beam of light, the secondary light having been generated by fluorescing the fluorescent dots with the received beam of light and the secondary light having a wavelength λ′ different from the wavelength λ; and   optically directing the separated secondary light toward a sensor.   
   
   
       2 . The method recited in  claim 1  further comprising focusing the directed separated secondary light onto the sensor. 
   
   
       3 . The method recited in  claim 1  further comprising filtering the directed separated secondary light to block light at wavelength λ. 
   
   
       4 . The method recited in  claim 1  wherein λ is approximately 808 nm and λ′ is approximately 1064 nm. 
   
   
       5 . The method recited in  claim 1  wherein the beam of light is substantially monochromatic. 
   
   
       6  . A device for profiling a beam of light that includes a wavelength λ, the device comprising:
 a prism;   a film of fluorescent material disposed over a surface of the prism oriented to receive the beam of light, wherein:
 the fluorescent material radiates light at a wavelength λ′ different from wavelength λ in response to excitation by the beam of light; and 
 the prism is substantially transparent to wavelengths λ and λ′; 
   a light sensor; and   an optical arrangement configured to separate the light at wavelength λ′ from the beam of light and to direct the light at wavelength λ′ to the light sensor.   
   
   
       7 . The device recited in  claim 6  wherein the optical arrangement includes a surface within the prism that substantially transmits light having a wavelength of one of λ and λ′ and substantially reflects light having a wavelength of the other of λ and λ′. 
   
   
       8 . The device recited in  claim 6  wherein the optical arrangement includes a lens disposed to focus the light directed to the light sensor onto the light sensor. 
   
   
       9 . The device recited in  claim 8  wherein the optical arrangement further includes a filter having transmission characteristics that block transmission of light having wavelength λ disposed to filter the light focused onto the light sensor. 
   
   
       10 . The device recited in  claim 6  wherein the light sensor comprises a photodetector. 
   
   
       11 . The device recited in  claim 6  wherein the light sensor comprises a camera. 
   
   
       12 . The device recited in  claim 6  wherein wavelength λ is less than 1064 nm and the fluorescent material comprises Nd:YAG. 
   
   
       13 . The device recited in  claim 6  wherein wavelength λ is less than 1064 nm and the fluorescent material comprises Nd ions embedded in a glass. 
   
   
       14 . The device recited in  claim 6  wherein the beam of light is substantially monochromatic. 
   
   
       15 . A device for profiling a beam of light that includes light with a wavelength λ, the device comprising:
 a disk rotatable about a central axis of the disk, the disk being oriented to receive the beam of light;   a plurality of fluorescent dots embedded within the rotatable disk in a spiral pattern around the central axis of the disk, wherein the fluorescent dots radiate light at a wavelength λ′ different from wavelength λ in response to excitation by a beam of light of wavelength λ;   a light detector; and   light directing means for separating light with wavelength λ′ from light with wavelength λ and for directing the light with wavelength λ′ toward the light detector.   
   
   
       16 . The device for profiling a beam of light according to  claim 15  wherein the light directing means includes an optical element with a coating that transmits light with wavelength λ and reflects light with wavelength λ′. 
   
   
       17 . The device for profiling a beam of light according to  claim 15  wherein the light directing means includes an optical element with a coating that transmits light with wavelength λ′ and reflects light with wavelength λ. 
   
   
       18 . The device for profiling a beam of light according to  claim 15  wherein the light directing means includes a Winston cone. 
   
   
       19 . The device for profiling a beam of light according to  claim 15  wherein the light directing means includes a filter having transmission characteristics that block transmission of light having wavelength λ. 
   
   
       20 . The device for profiling a beam of light according to  claim 15  wherein the fluorescent dots comprise Nd:YAG.