Abstract: There is provided a method of calculating a temperature corrected sample position in an interferometric microscope, the method comprising projecting an autofocus beam onto the sample location to form a reflected ring of radiation, detecting an uncalibrated radius. R, of a peak of the annulus of the reflected ring which indicates an uncalibrated sample position, detecting one or more of the width of the annulus or an intensity of the annulus and calculating a calibrated radius Rnorm using at least one of the width of the annulus or the intensity of the annulus to determine the temperature dependent corrected sample position.

Abstract: A method of imaging a sample by interferometric scattering microscopy, the method comprising illuminating a sample with at least one light source, the sample being held at a sample location comprising a reflective surface, such that a reflected signal is formed; the reflected signal comprising light from the light source and light scattered by the sample; detecting the output light over a first time window for a first frame N1; detecting the output light over a second time window for a second frame N2; calculating a ratiometric signal R which is the ratio of N1 and N2 minus 1; estimating the ratiometric motion signature S=(Sx, Sy) from frames N1 and N2 with S defined as the ratiometric image which would be measured from an invariant sample moving along x and y for a given motion vector m=(mx, my); estimating m as the most consistent vector such that R is approximated using S and m; calculating the corrected ratiometric contrast image R* from R, S and m.

Abstract: The application discloses a method and apparatus for imaging a sample by interferometric scattering microscopy, the method comprising illuminating a sample with at least one coherent light source, the sample being held at a sample location comprising an interface having a refractive index change, illuminating the sample with illuminating radiation to generate a backpropagating signal from the sample comprising light reflected at the interface and light scattered by the sample, splitting the backpropagating signal into first and second signals, modifying the second signal using a modifying element such that the second signal differs from the first signal, directing the first and second signals onto first and second detectors to generate, respectively, first and second images and comparing, by a processor, the first and second images to determine one or more characteristics of the sample.

Abstract: A method comprising the steps of: measuring a first series of interferometric scattering microscopy (iSCAT) signals and a second series of iSCAT signals of a sample on a sample holder, the sample comprising a particle dissolved in solution; deriving an illumination heterogeneity for the first series of iSCAT signals; deriving a reflectance profile for the first series of iSCAT signals based on the illumination heterogeneity and/or the second series of iSCAT signals; measuring a third series of iSCAT signals of the sample on the sample holder; and normalizing an interferometric contrast for the third series of iSCAT signals with the reflectance profile.