Optical tweezers move particles of different sizes with different physics involved, so here’s the one that’s easiest to understand.We know that visible light is refracted through transparent media such as glass and water, and the degree of deflection of light depends on the refractive index of the medium.In optical tweezers, we choose light that passes through bacteria and viruses waiting to manipulate objects.In this way, when light passes through objects such as bacteria, it bends in the same way that visible light bends through glass.We know from experience that when a flying ball is struck with a club, the direction of movement of the ball changes because the club exerts a force on the ball.The ball will move in different directions depending on the direction of the force applied.On the other hand, if we see for a short period of time that a baseball that was going in one direction changes direction, or reverses direction, or turns, we can say that there must have been a force on the baseball during that time.Back to the situation of optical tweezers, when the light deviates through the medium, its propagation direction changes, so we can say that the medium exerts a force on the light.Since the forces act on each other, when the medium exerts a force on the light, the light in turn exerts a force on the medium.So when a particular light is refracted through bacteria and viruses, it exerts a force on them.The light incident in different directions is refracted in different directions, so the force naturally exerted on the dielectric material has different directions.Therefore, in the optical tweezers technology, the object under control is treated at the same time to illuminate multiple beams of light incident in different directions, so that the object can feel the force exerted by the light in different directions after being refracted.The combined effects of these forces, like “tweezers”, grip the manipulated object firmly, allowing it to move, flip, and so on as desired, according to the scientist’s Settings, for further study.