Transparent surfaces that become opaque

In summary, there are materials such as photochromic lenses and electric switchable glass that can go from transparent to opaque when a bright light is shined on it. These materials can act like a window until a movie is projected onto it, and then become opaque in the regions where the light hits it at certain levels of brightness. However, there may be limitations with using these materials in direct sunlight or during a power outage.
  • #1
LightningInAJar
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TL;DR Summary
Surfaces that change transparency.
Are there any materials that go from transparent to opaque when a bright light is shined on it? In particular I would like something that acts like a window until I project a movie onto it and then is opaque in the regions where the light hits it at certain levels of brightness.
 
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  • #3
LightningInAJar said:
Are there any materials that go from transparent to opaque when a bright light is shined on it? In particular I would like something that acts like a window until I project a movie onto it and then is opaque in the regions where the light hits it at certain levels of brightness.
If sunshine falls on the window, or it is a bright day, the window will become opaque.
No projector can compete with sunlight.
Maybe an LCD window is needed with a separate control.
 
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  • #4
You can also get glass which becomes opaque when you pass a current through it.

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https://www.smartglassinternational.com/electric-switchable-glass/
 
  • #5
Baluncore said:
If sunshine falls on the window, or it is a bright day, the window will become opaque.
No projector can compete with sunlight.
Maybe an LCD window is needed with a separate control.
I would not use it in sunlight.
 
  • #7
Jarvis323 said:
You can also get glass which becomes opaque when you pass a current through it.
Erm. Does this means that these will switch transparent in case of a power outage?

Just asking :doh:
 
  • #8
Rive said:
Erm. Does this means that these will switch transparent in case of a power outage?
Smart glass does not have “a current pass through it” as that would be very inefficient. Switchable glass has a liquid crystal film, between transparent conductive layers, within the laminate that change optical characteristics when subjected to an electric field.
The glass becomes transparent only when a voltage is applied.
Loss of power does not lead to loss of dignity.
 
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1. What causes transparent surfaces to become opaque?

Transparent surfaces can become opaque due to a change in their physical or chemical properties. This can be caused by factors such as temperature, pressure, or exposure to certain chemicals or light. For example, glass can become opaque when exposed to extreme heat, causing it to melt and lose its transparency.

2. How can transparent surfaces become opaque without any external factors?

Some transparent materials, such as certain types of glass, can become opaque over time due to a process called devitrification. This occurs when the glass slowly crystallizes, causing it to lose its transparency and become more opaque. This process can also be accelerated by exposure to moisture or other environmental factors.

3. Can transparent surfaces become opaque temporarily?

Yes, some transparent materials can become opaque temporarily due to a phenomenon called reversible photochromism. This occurs when the material's molecules change their structure in response to light, causing the material to temporarily lose its transparency. An example of this is transition lenses, which become darker in bright sunlight but return to their transparent state indoors.

4. Are there any benefits to transparent surfaces becoming opaque?

In some cases, transparent surfaces becoming opaque can have practical benefits. For example, materials that become opaque in response to light can be used for privacy or to control the amount of light entering a space. This can be useful for windows, eyeglasses, and other applications.

5. Can transparent surfaces be made to become opaque on demand?

Yes, there are materials that can be engineered to become opaque on demand, such as smart glass. This type of glass contains a special coating or layer that responds to an electrical current, causing it to change from transparent to opaque. This technology is often used in windows, allowing for control over privacy and light levels without the need for blinds or curtains.

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