Optical measuring system
AssigneeThomas Swan & Co. Ltd.
InventorMelanie Holmes
Life of this patent
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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.
Claims18
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.
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.
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.
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.
Dependencies are inferred from the claim text.