Optical measuring system
First Claim
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1. Apparatus for characterising a spatially coherent beam of light, comprising:
- a LCOS SLM arranged so that a said beam of light can be incident upon it;
means for causing the LCOS SLM to display a first hologram pattern;
means for causing the LCDS SLM to display a second hologram pattern at a location in said beam where the amplitude and phase of the beam are to be characterised;
means for changing the second hologram pattern displayed on the LCDOS SLM; and
means for measuring an intensity of light to determine the effect of said change of hologram pattern.
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Abstract
Apparatus and methods are described for measuring amplitude and phase variations in a spatially coherent beam of light. A beam of coherent light is made incident upon a spatial array of phase modulating elements displaying a pixellated first phase distribution. In a measuring region of said spatial array, the phase distribution is changed to a new value while retaining the first phase distribution outside the measuring region, for example by flashing a single pixel. The change in intensity resulting from the change in phase distribution is then determined.
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Citations
21 Claims
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1. Apparatus for characterising a spatially coherent beam of light, comprising:
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a LCOS SLM arranged so that a said beam of light can be incident upon it; means for causing the LCOS SLM to display a first hologram pattern; means for causing the LCDS SLM to display a second hologram pattern at a location in said beam where the amplitude and phase of the beam are to be characterised; means for changing the second hologram pattern displayed on the LCDOS SLM; and means for measuring an intensity of light to determine the effect of said change of hologram pattern. - View Dependent Claims (2, 3, 4, 5)
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6. A method for alignment of an optical system by use of a Spatial Light Modulator, SLM, the SLM having phase modulating elements, the method comprising:
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a. rendering a beam incident on the SLM; b. measuring the transverse phase and/or amplitude distribution of the beam on the SLM by varying a displayed phase distribution of the phase modulating elements; and c. performing relative movement between the beam and the SLM to achieve a desired alignment of a feature of the beam with respect to the SLM. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of measuring transverse amplitude and phase variations in a spatially coherent beam of light comprising:
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a. causing the beam to be incident upon a spatial array displaying a pixellated first phase distribution, in a measuring region of said spatial array; b. causing the phase distribution to change to a new value while retaining the first phase distribution outside the measuring region, in the Fourier plane; c. determining the intensity resulting from the first change in phase distribution, outside the measuring region applying a second change in phase distribution, in the Fourier plane; and d. determining the intensity resulting from the second change on phase distribution.
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Specification