Abstract: A method of measuring the surface roughness of a component using an optical system comprising a tunable laser light source and a camera system. Positioning the component to be measured upon a mount in front of the optical system. Capturing a first image of the component at a first location at a first wavelength ?1, and then capturing a second image of the component at the first location at a second wavelength ?2. Determining the Speckle Statistical Correlation (SSC) coefficient of the first and second images. Plotting the SSC coefficient for the combined first and second images. Calculating the roughness parameters Ra and Rq from the SSC coefficient plot. Plotting a roughness map for the imaged surface from the calculated roughness parameters Ra and Rq. Moving the optical system to a new location and repeating steps (b) to (f) at the new location, and repeating these steps until a desired area of the component has been imaged.

Abstract: An imaging probe (102) for use in measuring surface roughness by angular speckle correlation is shown. The imaging probe comprises a first illumination fibre (201) to illuminate a sample location (103) on a surface, and having an input end for coupling of coherent light into the fibre, and an output end cleaved at an angle ?1, a second illumination fibre (202) to illuminate the sample location on the surface, and having an input end for coupling of coherent light into the fibre, and an output end cleaved at an angle ?2 that is different from ?1, and an image transmission system (204) for transmission of a speckle pattern caused by illumination of the sample location on the surface by coherent light from either the first illumination fibre or the second illumination fibre.

Abstract: An imaging probe (102) for use in measuring surface roughness by angular speckle correlation is shown. The imaging probe comprises a first illumination fibre (201) to illuminate a sample location (103) on a surface, and having an input end for coupling of coherent light into the fibre, and an output end cleaved at an angle ?1, a second illumination fibre (202) to illuminate the sample location on the surface, and having an input end for coupling of coherent light into the fibre, and an output end cleaved at an angle ?2 that is different from ?1, and an image transmission system (204) for transmission of a to speckle pattern caused by illumination of the sample location on the surface by coherent light from either the first illumination fibre or the second illumination fibre.