What Is a Quarter-Wave Plate?

A quarter-wave plate is also called a "quarter delay board". When light of a certain wavelength is incident perpendicularly, the phase difference between the emitted ordinary light and abnormal light is 1/4 wavelength. In the optical path, it is often used to make linearly polarized light or circularly polarized light; or vice versa. This wave plate is usually made of a parallel plane plate by cutting birefringent material in a direction parallel to the optical axis, and its thickness should be exactly an odd multiple of the product of the refractive index difference between the two major axes of the birefringent material and a given wavelength 1/4. Wave plates made of optically active materials that can rotate the polarization plane of the incident light by an odd multiple of x / 2 are also called quarter wave plates. ^[1]

Quarter-wave plate A birefringent single crystal wave plate of a certain thickness. When light passes through the waveplate from normal incidence,

Use other

A wave plate is an optical element used to change the polarization state of light. It can be a wafer cut parallel to the optical axis of a birefringent crystal such as crystal or calcite, or it can be made of a mica sheet, cellophane, or polyvinyl alcohol, which has directivity to incident light. The principle is that the incident monochromatic polarized light is divided into two polarized components and they propagate at different speeds. Through the thickness of the wave plate, the phase of the two components produces ridges and recombines, which changes the original polarization state. Generally, the phase difference is divided into a full wave plate, a half wave plate, a quarter wave plate, and the like. Wave plates are often used to turn linearly polarized light into circularly polarized light or elliptically polarized light; they can also be used to convert circularly polarized light into linearly polarized light.

When monochromatic polarized light is perpendicularly incident on the wafer, when the thickness d of the wafer is selected so that the phase difference between o light and e light after passing through the wafer is = 2K, the synthetic vibration equation is:

The synthetic vibration is linearly polarized light, and the optical path difference = K caused by this wafer. A wafer that meets this condition is called a full wave plate. The linearly polarized light passes through the full wave plate, and the vibration state is unchanged. The outgoing light and the incident light vibrate in the same direction and are still linearly polarized light. ^[2]

Also called "half-wave plate". Between the phases of the two polarization components of the incident light wave, a relative phase shift of r / 2 is introduced. Radian wave plate. Commonly used to generate polarized light orthogonal to the polarization state of incident light, and to turn right-handed circularly polarized light or elliptically-polarized light to left-handed, or left-handed to right-handed. ^[3]