The detection principle of optical detection equipment is mainly based on the characteristics of light and optical phenomena.
Light has wave and particle properties, which enables it to interact with objects and generate various detectable signals. Common optical detection principles include:
Reflection principle: When light hits the surface of an object, it will reflect. Objects with different materials and surface states have different characteristics such as the intensity and angle of reflected light. By detecting these characteristics of reflected light, the surface quality, shape, size and other information of the object can be judged. For example, a photoelectric sensor is used to detect the change in the intensity of reflected light on the surface of an object to determine whether the object has defects or flaws.
Refraction principle: When light enters from one medium to another, it will refract, and the refraction angle is related to the refractive index of the medium. By measuring the angle of the refracted light or the change in the refractive index, the material properties, thickness, etc. of the object can be determined. For example, in the quality inspection of optical glass, the uniformity and refractive index of the glass are evaluated by measuring the refraction angle of the light when it passes through the glass.
Interference principle: When two coherent light beams meet, interference occurs, forming interference fringes of light and dark. By observing the shape and spacing of interference fringes, the object's micro-displacement, flatness, etc. can be measured. In some high-precision optical measuring instruments, such as interference microscopes, the interference principle is used to measure the surface morphology of objects.
Diffraction principle: When light passes through obstacles such as small holes or slits, it will diffract, and the diffraction pattern is related to the shape and size of the obstacle. By analyzing the diffraction pattern, the structure and size information of the object can be inferred. For example, in X-ray diffraction technology, the diffraction phenomenon of X-rays is used to analyze the structure of crystals.
Absorption principle: Different substances have different absorption characteristics for light. Some substances absorb light of a specific wavelength and present a specific color or transmittance. By detecting the absorption of light, the composition and concentration of the substance can be determined. For example, in chemical analysis, a UV-visible spectrophotometer is used to measure the absorption of a substance by a specific wavelength of light to determine the content of the substance.
In short, optical detection equipment can detect various physical and chemical properties of objects by cleverly utilizing various characteristics and phenomena of light. It has the advantages of non-contact, high precision, and high speed, and has been widely used in industrial production, quality control, scientific research and other fields.
