Transmission of blue light through ceramics and surface roughness effects

In summary, the conversation discusses the measurement of blue visible light through lithiumdisilicate ceramics using an ulbricht ball and spectrometer, with a led dental curing unit as the light source. Different surface conditions were tested and it was found that the transmission was lower when the roughness of the ceramic was higher. Testing with a thin film of immersion oil resulted in a 3% decrease in transmission, contrary to the expected increase due to lower reflection on the surface. The phenomenon is attributed to thin film interference. The speaker also mentions trying this on both rough and smooth surfaces and finding consistent results.
  • #1
ccdani
2
0
Hey :)

I measured the transmission of blue visible light (350-550nm) through lithiumdisilicate ceramics with an ulbricht ball and an spectrometer. The light source was a led dental curing unit (bluephase style). The light guide was positioned direct on the ceramics.
Now I wanted to test different surface conditions. The transmission was lower when the roughness of the ceramic is higher. Then I tested the transmission with a thin film of immersion oil (refractive index 1.51) between the light guide and the ceramics. I thought that the degree of transmission has to be higher because of the lower reflection on the surface.
But it was 3% lower. I thought that there is less reflection at the surface with immersion oil because of the similar refractive index of immersion oil than of air.
Can you explain this phenomenon? Is it because of thin film interference?

Thank you very much!
 
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  • #2
Did you try this on both rough and smooth surfaces? Was the decrease in the degree of transmission consistent for both?
 
  • #3
I've tried it on both (also glasured ceramics) also on other thicknesses. When I measured the same thickness there was the same decrease of Transmission. The higher the thickness the lower is the difference between with immersion oil or with no Immersion oil.
 

1. How does the surface roughness of ceramics affect the transmission of blue light?

The surface roughness of ceramics can impact the transmission of blue light in several ways. First, rougher surfaces tend to scatter light, reducing the overall transmission. This is because the surface irregularities cause the light to bounce off in different directions, rather than passing through the material. Additionally, rough surfaces can create microcracks or defects that can absorb light, further reducing transmission. However, in some cases, surface roughness can also improve transmission by reducing reflections and increasing the surface area for light to pass through.

2. Are there any specific types of ceramics that have a higher transmission of blue light?

Yes, there are certain types of ceramics that have a higher transmission of blue light. For example, alumina and zirconia ceramics have been found to have high transparency in the blue light spectrum. This is due to their crystal structure, which allows for efficient transmission of blue light. Additionally, ceramic materials with a smoother surface finish tend to have higher transmission rates compared to rougher surfaces.

3. How does the thickness of the ceramic material affect the transmission of blue light?

The thickness of the ceramic material can greatly impact the transmission of blue light. Thicker ceramics tend to have lower transmission rates, as the light has to travel through a greater distance and can be absorbed or scattered along the way. On the other hand, thinner ceramics may have higher transmission rates, but this also depends on factors such as the type of ceramic and surface roughness. In general, a thinner ceramic material with a smoother surface will have higher transmission of blue light.

4. Can surface treatments or coatings improve the transmission of blue light through ceramics?

Yes, surface treatments or coatings can be used to improve the transmission of blue light through ceramics. For example, polishing the surface of a ceramic can reduce surface roughness and improve transmission. Coatings such as anti-reflective coatings can also be applied to reduce the amount of light that is reflected off the surface, increasing transmission. However, it is important to note that these treatments may also alter other properties of the ceramic material.

5. Is the transmission of blue light through ceramics affected by the angle of incidence?

Yes, the angle of incidence can affect the transmission of blue light through ceramics. This is because the angle of incidence determines how much light is reflected off the surface, and how much is transmitted. For example, if the angle of incidence is perpendicular to the surface, more light will be transmitted compared to when the angle is parallel to the surface. This is known as the Brewster angle and can be used to optimize the transmission of blue light through ceramics.

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