Phase-stepping interferometry of GaAs nanowires: Determining nano-wire radius

Abstract

Phase stepping interferometry is used to measure the size of near-cylindrical nanowires. Nanowires with nominal radii of 25 nm and 50 nm were used to test this by comparing specific measured optical phase profile values with theoretical values calculated using a wave-optic model of the Phase stepping interferometry (PSI) system. Agreement within 10% was found, which enabled nanowire radii to be predicted within 4% of the nominal value. This demonstration highlights the potential capability for phase stepping interferometry to characterize single nanoparticles of known geometry in the optical far-field. V

Optical emission spectroscopy system operating in the vacuum-ultraviolet spectral rangeλ< 100 nm—a semi-empirical determination of sensitivity

“…We have no specific details of the experiment, and the calculation methodology/ assumptions used to determine their grating efficiencies. In particular, details of the theoretical model employed by Horiba to generate the subsequent grating response curve 10 and their assumed groove height h for the grating is proprietary information. Therefore it is difficult to comment further on the reliability of the data points provided by Acton.…”

“…The grating was illuminated with a filtered white-light source with a central wavelength of 535 nm and a bandwidth of approximately 50 nm, and a 115 × magnification, 0.80 numerical aperture Mirau objective was used to image the grating. Lateral calibration of the instrument (the X-Y scales in μm) was performed using a 20 μm pitch grating, within a precision of 2.5% [10]. The Rayleigh limit on the lateral resolution of the instrument (R ~ 0.61λ/ NA ~ 0.4 μm) [10] is sufficiently small to resolve the groove spacing d = 0.833 μm of the grating.…”

“…Lateral calibration of the instrument (the X-Y scales in μm) was performed using a 20 μm pitch grating, within a precision of 2.5% [10]. The Rayleigh limit on the lateral resolution of the instrument (R ~ 0.61λ/ NA ~ 0.4 μm) [10] is sufficiently small to resolve the groove spacing d = 0.833 μm of the grating. The z-axis of the surface profile was calibrated, with a precision of 0.3 nm, using a frequency-stabilised HeNe reference laser.…”

Considerations on the proposed linear theory of surface measurement for coherence scanning interferometers

“…Recently, the application of similar ideas to cases where large strongly scattering objects are being imaged was attempted by the authors of [3][4][5], with apparent success, and this work has subsequently been considered as a possible route by which coherence scanning interferometers (CSIs) could be calibrated [4][5][6][7][8][9][10], or inform us about the imaging process [11][12][13][14][15][16][17][18][19][20][21].…”