An orthogonal-transmitting double-beam optical trap system for wide-range and high-precision relative gravimetry

We propose an orthogonal-transmitting double-beam optical trap (OTDBOT) scheme for both three-dimensional capture of microspheres and relative gravitational acceleration sensing. One weak-focused vertical beam provides axial scattering force to counteract initial gravity of sensing microspheres, and one horizontal highfocused beam forms radial gradient force to provide relative gravimetry. This optical trap system can achieve a wide dynamic measurable range of up to +/- 1 kGal and high sensitivity in the order of mu Gal/v Hz in high vacuum only by an optical-trapped microsphere and trapping laser with less than 1 W, theoretically. The sensing properties of this scheme with different noncoplanar offsets and non-orthogonal tilts are also calculated. Numerical simulation results show that excessive offset distance will decline the dynamic measurement range and vertical trap stiffness, but the tilt angle within 15 degrees will almost not. Both the distance and angle will not lead to the sensing microsphere escaping from the trap.

Automated summary

We propose an orthogonal-transmitting double-beam optical trap (OTDBOT) scheme for three-dimensional capture of microspheres and relative gravitational acceleration sensing. The system uses a weak-focused vertical beam to counteract the initial gravity of the microspheres and a horizontal high-focused beam to provide relative gravimetry. The scheme has a wide dynamic measurable range and high sensitivity.