Optically pumped magnetometer

An optically pumped magnetometer using atomic electron spin or nuclear spin, comprising:

• a cell containing at least a first alkali-metal atom group and a second alkali-metal atom group interacting via spin exchange with the first alkali-metal atom group;
• a pump light system for making a pump light enter the cell, where the pump light has a first wavelength to spin-polarize the first alkali-metal atom group;
• a probe optical system to make a probe light enter the cell to form an optical axis identical to the pump light, where the probe light has a second wavelength different from the first wavelength, and where the probe light measures spin polarization of the second alkali-metal atom group;
• a wavelength discrimination unit for discriminating between the pump light and the probe light that passed through the cell depending on a different in wavelength;
• and
• a measuring unit for measuring a rotation angle of a polarization plane of the probe light that passed through the cell.