Photoacoustic joulemeter utilizing beam deflection technique
AssigneeThe Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc.
InventorsWilliam Rowe Elliott, Randolph D. Glickman, Norman Barsalou, Saher M. Maswadi
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Abstract
A joulemeter is capable of non-destructively measuring multiple characteristics of a laser beam. The joulemeter comprises a series of parallel probe beams, which are directed though a transparent media adjacent to an absorbing media that the tested beams pass through. Arrays of optical sensors or a chirp sensor are used to intercept and measure deflections the probe beams. A control unit renders measurements on selected properties of the laser.
Claims23
A joulemeter for non-destructively measuring electromagnetic radiation, comprising:
- a plurality of absorbing media aligned with an electromagnetic radiation source such that a beam generated by said radiation source passes through at least one of said plurality of absorbing media;
- at least one light or electromagnetic radiation source capable of generating a plurality of probe beams, wherein said probe beams are directed through the absorbing media or a second medium adjacent to said absorbing media;
- at least one sensor positioned to receive and measure said probe beams, wherein said sensor does not obstruct said electromagnetic radiation beam;
- a control unit that selects an absorbing media based on the expected wavelength of said electromagnetic radiation and is configured to receive signals from said sensor or sensors, and convert the output into measurements of selected characteristics of the beam.
A method of measuring selected properties of a pulse laser beam, comprising the steps of:
- selecting an absorption media based on the power of the laser beam to be measured and the absorption coefficient of each glass;
- positioning absorbing media in the path of said electromagnetic beam;
- directing a plurality of probe beams in a second media adjacent to said absorbing media;
- measuring probe beam deflections using at least one sensor positioned to receive probe beams, wherein said sensor does not obstruct said electromagnetic radiation beam;
- rendering measurements on at least one of said selected properties of said electromagnetic radiation.
A method of measuring selected properties of a continuous wave electromagnetic radiation beam, comprising the steps of:
- modulating said continuous wave electromagnetic radiation beam with a disk-shaped absorption medium, wherein
- at least two regions of said disk-shaped absorption media have different absorption coefficients, and
- said disk-shaped absorption media is rotated at a known frequency;
- positioning an absorption medium in the path of said electromagnetic radiation beam;
- directing a plurality of probe beams in a second medium adjacent to said absorbing medium;
- measuring probe beam deflections using at least one sensor positioned to receive and measure said probe beams, wherein said sensor does not obstruct said electromagnetic radiation beam;
- rendering measurements on at least one of said selected properties of said electromagnetic radiation beam, wherein said selected properties are selected from the list consisting of:
- pulse energy;
- beam diameter;
- energy density;
- beam power;
- beam profiling;
- and
- spot size.
A method of controlling the beam characteristics of a laser or electromagnetic radiation beam, comprising the steps of
- positioning disk shaped absorbing media, said disk-shaped absorbing media comprising at least two regions of different absorption coefficients, in the path of said laser or electromagnetic radiation beam;
- directing a plurality of probe beams in a second media adjacent to said absorbing media;
- measuring probe beam deflections using at least one sensor positioned to receive probe beams, wherein said sensor does not obstruct said laser or electromagnetic radiation beam;
- rendering measurements on at least one of said selected characteristics of said laser or electromagnetic radiation beam;
- and
- modulating control parameters of the laser or electromagnetic radiation beam in order to match the measured beam characteristics to the desired beam characteristics, wherein said beam characteristics are selected from the list consisting of:
- pulse energy;
- beam diameter;
- energy density;
- beam power;
- beam profiling;
- and
- spot size.
Dependencies are inferred from the claim text.