Optical measuring system
First Claim
1. A method of measuring amplitude and phase variations in a spatially coherent beam of light comprisingcausing the beam to be incident upon a spatial array displaying a pixellated first phase distribution,in a measuring region of said spatial array, causing the phase distribution to change to a new value while retaining the first phase distribution outside the measuring region,in the Fourier plane, determining the change in intensity resulting from the change in phase distribution.
1 Assignment
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Accused Products
Abstract
Apparatus and methods are described for of 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
18 Claims
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1. A method of measuring amplitude and phase variations in a spatially coherent beam of light comprising
causing the beam to be incident upon a spatial array displaying a pixellated first phase distribution, in a measuring region of said spatial array, causing the phase distribution to change to a new value while retaining the first phase distribution outside the measuring region, in the Fourier plane, determining the change in intensity resulting from the change in phase distribution.
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2. A method of characterising a spatially coherent beam of light, comprising
disposing a LCOS SLM in the path of the beam; -
causing the LCOS SLM to display a first hologram pattern; at a location in said beam where the amplitude and phase of the beam are to be characterised, changing the hologram pattern to a second hologram pattern; and measuring the effect of said change by determining an intensity change. - View Dependent Claims (3, 8, 9)
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12. Apparatus for measuring amplitude and phase variations in a spatially coherent beam of light, the apparatus comprising a pixellated spatial array, each pixel being controllable to apply any of plural phase shifts to input light, whereby the array displays a desired distribution of phase modulation,
means for causing the array to display a first selected distribution of phase modulation; - means for changing the first distribution in a measuring region of said spatial array to assume a new distribution while retaining the first phase distribution outside the measuring region,
means disposed in the Fourier plane for determining a change in intensity of light resulting from the change in phase distribution. - View Dependent Claims (13, 14)
- means for changing the first distribution in a measuring region of said spatial array to assume a new distribution while retaining the first phase distribution outside the measuring region,
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15. 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 changing the hologram pattern to a second hologram pattern at a location in said beam where the amplitude and phase of the beam are to be characterised; and means for measuring an intensity of light to determine the effect of said change of hologram pattern. - View Dependent Claims (16, 17, 18)
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Specification