Absolute gravimeter and measurement method based on vacuum optical tweezers

An absolute gravimeter based on vacuum optical tweezers, comprising a vacuum system, micro-nano particles, a micro-nano particle releasing device, laser optical tweezers, an optical interferometer, and a signal processing device;

• wherein the micro-nano particle releasing device and the laser optical tweezers are all placed in the vacuum system;
• the optical interferometer and the signal processing device are all located outside the vacuum system;
• the micro-nano particle releasing device is equipped with the micro-nano particles, the micro-nano particle releasing device is located above the laser optical tweezers, and the laser optical tweezers comprising two capturing beams which are horizontally coaxial and two convergent lenses, the two capturing beams pass through the respective convergent lenses and then converge at an intersection, an area where the intersection is located serves as an optical trap capturing region, and the micro-nano particles are stably captured by the two capturing beams in the optical trap capturing region;
• the optical interferometer is electrically connected to the signal processing device, the optical interferometer measures a displacement of the micro-nano particles in real time at the beginning of a free fall process from the optical trap capturing region and sends a displacement signal to the signal processing device, the signal processing device obtains a measured value of an absolute gravitational acceleration through method processing according to a real-time displacement of the micro-nano particles,
• wherein the optical interferometer comprises a laser, an upper emitting mirror, a lower emitting mirror, an upper polarizing beam splitting prism, a lower polarizing beam splitting prism, a receiving polarizing beam splitting prism, an upper glass plate, a lower glass plate, and a polarizer, the upper polarizing beam splitting prism and the upper glass plate are provided right above gravity drop of the micro-nano particles, the upper emitting mirror is arranged on a lateral side of the upper polarizing beam splitting prism, and the lower polarizing beam splitting prism and the lower glass plate are arranged directly under gravity drop of the micro-nano particles, the lower emitting mirror is set directly under the lower polarizing beam splitter prism, and the receiving polarizing beam splitter prism and the polarizer are arranged on a lateral side of the lower emitting mirror;
• the laser emits first and second linearly polarized beams with different frequencies, the first linearly polarized beam is transmitted through the upper polarizing beam splitter prism and the upper glass plate in turn from right above the micro-nano particles along a positive direction of a gravity direction, and then irradiated on the micro-nano particles, after being scattered by a surface of the micro-nano particles, an upper scattered light is generated, and the upper scattered light returns upward along an optical path, is transmitted by the upper glass plate, reflected by the upper polarizing beam splitter prism, and then incident on the upper emitting mirror, and incident on the receiving polarizing beam splitter prism after being reflected by the upper emitting mirror, and is reflected again, thus forming a first probe optical path, the second linearly polarized beam is reflected by the lower polarizing beam splitter prism in turn from a bottom of the micro-nano particles in an opposite direction of the gravity direction, and transmitted through the lower glass plate, and then irradiated to the micro-nano particles, after being scattered by the surface of the micro-nano particles, a lower scattered light is generated, and the lower scattered light is returned downward along the optical path, transmitted by the lower glass plate, reflected by the lower polarizing beam splitter prism, and then incident on the lower emitting mirror, and then incident on a receiving polarizing beam splitter prism after being reflected by the lower emitting mirror, and is transmitted again, thus forming a second probe optical path;
• the upper scattered light reflected by the receiving polarizing beam splitter and the lower scattered light reflected by the receiving polarizing beam splitter are converged and interfered, and then incident on a photoelectric conversion circuit through the polarizer to be collected and probed to obtain an interference signal.