Optical system of LIGO gravitational wave detector

The optical system of LIGO is quite complex and sophisticated, including the main optical system and the power supply systems for lasers as well as the equipment to suppress noise, suppress seismic impulses.

Overview of two laboratories located LIGO at Livingston, Louisiana and Hanford, Washington, USA.Thanks to these two detectors, for the first time in history, scientists discovered gravitational waves that existed in the universe thanks to two black holes merged in September 2015;promises to bring new breakthroughs in space science research.

LIGO stands for Laser Interferometer Gravitational-Wave Observatory , which means that the gravitational wave observatory is made of laser interference.

Principle diagram of the main optical system.(Photo: GW Optics).

The main optical system of LIGO for each interferometer consists of large mirrors placed on both ends, correction discs for mirrors, the main laser beam splitter, mirrors that enhance laser beam power (PRM) and signal reinforcement mirrors. Brand (SRM). The mass of these mirrors is about 40kg. The parts of the system are made of high purity molten silica and coated with tantala doped. The light scattering of mirrors with incident light is less than 10 parts per million to ensure sensitivity.

Mirror at equipment set in Livingston.

Laser beam splitter uses a prism.

Mirror enhances the power of PRM laser beam.

PSL laser beam pre-stabilizing system.

This system will provide stable light intensity and frequency for LIGO's interferometers, ensuring the correct specifications for the laser source at the input. Its main part is a 3-level laser system.

Optical input system controls and puts lasers from PSL into the main optical system.Its design also requires the ability to transform the radio frequency of light, choose the right mode for the light and drive the beam into the interferometer.

In addition, LIGO also has auxiliary systems such as destructive seismic impulse , vacuum removal to eliminate the effect of dust on the laser path, ensuring that the detector will only obtain gravitational waves if any; along with devices to collect and process and calculate data.