Principle of optical rotation analyzer

The optical rotation analyzer, usually referred to as the key part of the polarimeter, is used to measure the rotational effect of a substance on polarized light, so as to infer information such as the optical rotation property and concentration of a substance. Its working principle is mainly based on the polarization and rotation of light. The following is a detailed explanation of how the optical rotation analyzer works:

1.basic principles

Polarization of light:

Light is an electromagnetic wave with electric and magnetic components. Polarized light is light whose electric field components vibrate in a particular direction.

Through optical elements such as polarizers or Nicol prisms, polarized light in a specific direction can be obtained.

Optical rotation:

When polarized light passes through some material with a chiral molecular structure, the direction of the light's vibration will rotate. This phenomenon is called optical rotation.

The phenomenon of optical rotation is closely related to the molecular structure of substances, and different substances may rotate the polarized light at different angles and directions.

2.The composition and work flow of the optical rotation analyzer

The optical rotation analyzer usually consists of a light source, a polarizer, a sample chamber, an analyzer and a detector. Its work flow is as follows:

Light source:

Provides a steady beam of polarized light. The light source can be mercury lamp, sodium lamp or laser, modern polarimeter mostly uses LED light source, which has the advantages of long life and low power consumption.

Polarizer:

Converts the light emitted by a light source into polarized light in a specific direction. Polarizers are usually made of Nicol prisms or polarizers.

Sample room:

The area where the sample to be tested is placed. The sample chamber is usually a clear glass or quartz pool that allows polarized light to pass through the sample.

Analyzer:

The analyzer is the core part of the optical rotation analyzer, which is used to detect the rotation Angle of polarized light after passing through the sample.

The analyzer is also usually made of a polarizer （such as a Nicol prism or polarizer） that is set parallel to or at an Angle to the direction of the incident polarizer.

When the polarized light passes through the sample, its vibration direction rotates, and the analyzer measures the rotation Angle by adjusting its direction so that the polarized light can pass through after rotation.

Detector:

The detector is used to measure the light intensity after passing through the analyzer. When the vibration direction of the polarized light is consistent with the direction of the analyzer, the light intensity is maximum. When the direction is not consistent, the light intensity decreases.

By measuring the change in light intensity, the rotation Angle of polarized light can be calculated.

Signal processing and display:

The detector converts the light intensity signal into an electrical signal, and after signal processing, the value of rotation is obtained.

The rotation value is displayed on the monitor or computer interface for the user to read and analyze.

3. Workflow example

Light source luminescence: A light source emits a steady beam of polarized light.

Polarized light passes through the sample: The polarized light passes through the sample in the sample chamber, and the vibration direction of the light rotates due to the optical rotation of the sample.

Analyzer detection: the rotated polarized light enters the analyzer, and the analyzer adjusts its direction so that the rotated polarized light can pass through.

Detector measurement: The detector measures the light intensity after passing through the analyzer to obtain the value of rotation.

The result display: the rotation value is displayed on the monitor or computer interface.

4. Influencing factors and applications

Influencing factors:

The stability of the light source, the quality of the polarizer, the transparency of the sample chamber and other factors will affect the measurement accuracy of the rotation.

Material concentration, temperature, optical path length and other factors will also affect the value of rotation.

Applications:

Optical rotation analyzer is widely used in chemical, pharmaceutical, food and other fields. For example, in the pharmaceutical industry, it is used to detect the rotation of drugs to determine the purity and content of drugs; In the food industry, it is used to detect the content of sugar.

In summary, the optical rotation analyzer can measure the optical rotation properties and concentration of materials quickly and accurately by measuring the rotation effect of materials on polarized light.

2025-03-21 16:50