Diffuse refers to the irregular direction of light from a rough surfacereflexPhenomenon, also known asdiffuse reflection。Many objects, such as plants, walls, clothes, etc., have rough surfaces that seem smoothmagnifierAfter careful observation, we can see that its surface is uneven, so it is originally parallelsunlightReflected by these surfaces, they diffuse in different directions.
When a beam of parallel light touches the smooth object surface, the light will be reflected regularly, and the reflected light will also be parallel to each other. This regular reflection is called one-way reflection of light orSpecular reflection。However, the smoothness of objects is relative, and the surface of general objects is rough and uneven. Although the incoming ray isDirectional light, but the reflected light is scattered in all directions, which is called light diffusion[1]。
The reason why the human eye can see the full picture of an object is mainly due to the imaging of diffuse reflection light in the eye.If the surface of an object reflects in one direction, not only the appearance of the object can not be seen clearly, but also the glare in a certain direction can be causedInterference phenomenon。
Each diffuse ray followsReflection law。parallellight beamIt is no longer a parallel beam after diffusion.Objects formed by diffusionbrightness, general viewlight sourceIntensity and the nature of the reflector.
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Diffuse light refers to the light emitted from the light source entering the sample and returning to the sample surface after multiple reflections, refractions, scattering and absorption.Diffuse light is the light after analysis and interaction with the internal molecules of the sample, which carries rich sample structure and organizational information.Compared with diffuse transmission light, although the transmission light also carries the structure and tissue information of the sample, the intensity of the transmission light is affected by the thickness of the sample and the irregularity of the light path in the transmission process. Therefore, diffuse reflection measurement is more direct and reliable in extracting sample composition and structure information.
The integrating sphere is one of the common accessories in diffuse reflection measurement.After the incident light enters the sample, part of the diffuse light returns to the inside of the integrating sphere, and reaches the detector after multiple diffuses in the integrating sphere. Since the signal light emitted from the scattering plane passes through the spatial integration of the integrating sphere, it can overcome the influence of random factors in diffuse measurement, and improve data stability and repeatability.
Diffuse also follows the reflection law of light like specular reflection.
Similarities and differences
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As shown in the figure below, the same thing between diffuse and specular reflection is that they both follow the reflection law of light.
The differences are reflected in the reflective surface, the direction of reflected light, people's feelings, etc.As shown in Diffuse Reflection and Specular Reflection.
Diffuse reflection and specular reflection
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People measure the luminous flux according to the diffuse principle.Various for receivingoptical system AchievedReal imageAll screens shall be made of diffuse reflective surfaces with high diffusivity.In the laboratory, diffuse reflective surface of ground glass is often used as extended light source.In the cinema, people can see the pictures on the screen from different seats, because light forms diffuse reflection on the screen.Cinema screens and projection screens are the most common examples of diffuse reflection in life[1]。
People can see objects from different directions depending on the diffuse phenomenon.stayEnvironmental opticsThe matt finish material is often regarded as a uniform diffuse reflective surface, and the reverberation chamber used for sound absorption material testing has sufficient diffusion to keep its wall surface meeting diffuse reflective conditions.
Integrating sphere is a hollow sphere with a highly reflective inner surface.A high efficiency device used to collect the scattering or emission of light by the sample in the ball or placed outside the ball and close to a window.A small window on the ball allows light to enter and interact withdetectorCloser.The basic feature of the integrating sphere is one of the most common instruments in optics,Light energyThe application of is increasing in all aspects.for exampleFiber optics、Laser technology、Photographic chemistryandMedical technologyThe integrating sphere has been widely used in these fields, and is improving and replacing those complicated and expensive optical systems.Because the inner surface of the integrating sphere has the characteristics of ultra-high reflection and scattering, it has a unique performance of receiving and transmitting light.The irregular reflection of light on the uniformly distributed spherical wall makes the energy can be measured accurately. Just because the integrating sphere has this characteristic, changing its window position and geometric structure can obtain various applications.
