Geometrical optics — Videos Brownian motion in an optical trap (low NA). Brownian motion in an optical trap (medium NA). Brownian motion in an optical trap (high NA). Scattering of a ray on a spherical particle (high refractive index). Scattering of a ray on a spherical particle (low refractive index). Trapping efficiencies (high refractive index). Trapping efficiencies (low refractive index). Alignment for a prolate ellipsoidal particle. Kramers’ transitions in a double optical trap. Transversal optical trapping: NA=0.50 nm=1.33 np=1.50. Transversal optical trapping: NA=1.00 nm=1.33 np=1.50. Transversal optical trapping: NA=1.30 nm=1.33 np=1.50. Axial optical trapping: NA=0.50 nm=1.33 np=1.50. Axial optical trapping: NA=1.00 nm=1.33 np=1.50. Transversal optical trapping: NA=1.30 nm=1.33 np=1.50. Transversal optical trapping: NA=0.50 nm=1.33 np=1.00. Transversal optical trapping: NA=1.00 nm=1.33 np=1.00. Transversal optical trapping: NA=1.30 nm=1.33 np=1.00. Axial optical trapping: NA=0.50 nm=1.33 np=1.00. Axial optical trapping: NA=1.00 nm=1.33 np=1.00. Axial optical trapping: NA=1.30 nm=1.33 np=1.00. Axial optical trapping: NA=0.50 nm=1.60 np=1.00. Transversal optical trapping: NA=1.00 nm=1.60 np=1.00. Transversal optical trapping: NA=1.30 nm=1.60 np=1.00. Transversal optical trapping: NA=0.50 nm=1.60 np=1.00. Axial optical trapping: NA=1.00 nm=1.60 np=1.00. Axial optical trapping – NA=1.30 nm=1.60 np=1.00.