Do my parabolic mirrors need to be really shiny to reflect infrared?

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    Infrared Mirrors
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Discussion Overview

The discussion centers around the effectiveness of old parabolic mirrors in reflecting infrared light, specifically whether their shininess impacts their ability to reflect infrared radiation. Participants explore practical considerations for cleaning and polishing the mirrors to enhance their performance in an experimental setup.

Discussion Character

  • Exploratory, Technical explanation, Experimental/applied

Main Points Raised

  • One participant notes that the mirrors are not very shiny and questions whether they need to be polished to effectively reflect infrared light.
  • Another participant suggests that surface contamination, such as oxide and dust, must be removed as it can block infrared radiation, recommending the use of soapy water for cleaning.
  • There is a caution against leaving an IR absorbing film from commercial polish on the mirrors, emphasizing the importance of mechanical polishing for the final surface.
  • Participants encourage experimentation to assess the effectiveness of the cleaning methods before and after, highlighting the value of practical evidence in discussions.

Areas of Agreement / Disagreement

Participants generally agree on the need to clean the mirrors to remove contaminants, but there is no consensus on the necessity of achieving a high level of shininess for effective infrared reflection.

Contextual Notes

The discussion does not resolve the specific impact of shininess on infrared reflection, and assumptions about the properties of the mirrors and the cleaning methods remain unexamined.

Who May Find This Useful

Individuals interested in experimental physics, optics, or those looking to improve the performance of reflective surfaces in infrared applications may find this discussion relevant.

cj
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Summary:: Do my parabolic mirrors need to be really shiny to reflect infrared?

I have 2 really old CENCO parabolic reflectors.

I need to use them to demonstrate infrared light radiation by placing a heat source near one mirror, reflecting its heat to a second parabolic mirror and concentrating that mirror's reflected light to a match placed at the focal point.

Neither mirror is very shiny anymore. Should I clean and polish them to get them really shiny, or does this not really affect the reflection of IR?

Thank you!
 
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cj said:
Neither mirror is very shiny anymore.
You must remove the surface contamination of oxide and dust that will block IR.
Start with soapy water. That might fix a dust or dirt problem.
Polish the surfaces to clean them, but make sure that you do not leave an IR absorbing film from a commercial polish on the final surface. Finish with a mechanical polishing.

You have an opportunity to experiment with before and after assessments.
 
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Good advice, thanks!
 
Baluncore said:
You have an opportunity to experiment with before and after assessments.
Always. If ever in doubt then experiment.

Very powerful for argufying on PF, too. Such evidence works at least as well as CERN's for appropriate situations. It shows people you are really involved in the stuff.
 
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