How well can we 'see' at different wavelengths?

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Discussion Overview

The discussion revolves around the various methods of "seeing" or imaging different materials and objects using different types of waves, including light, infrared, ultrasound, and magnetic fields. Participants explore the capabilities, limitations, and distinctions of these methods, particularly in terms of resolution and the types of materials that can be imaged.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about a comprehensive table that outlines the pros and cons, limitations, and advantages of various imaging methods, including their resolution capabilities and the materials they can detect.
  • Another participant suggests looking up the relationship between the wavelength of light and the size of objects that can be resolved, implying a connection between wavelength and imaging capability.
  • Concerns are raised about whether wavelengths are always relevant in imaging methods, particularly in the context of magnetic fields.
  • A participant points out that modern scanning probe methods, such as near-field microscopy, allow for imaging with nanometer resolution using microwaves, emphasizing that resolution is primarily limited by the size of the tip used.
  • It is noted that near-field methods are distinct from atomic force microscopy (AFM) and scanning tunneling microscopy (STM), as they rely on collected light rather than direct force measurements.
  • Another participant reiterates the concern about the relevance of wavelengths in magnetic force microscopy (MFM), stating that it senses magnetic interactions directly without involving wavelengths.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the role of wavelengths in various imaging techniques, particularly in magnetic methods. There is no consensus on whether wavelengths are always a factor in these imaging methods.

Contextual Notes

The discussion highlights limitations in understanding the applicability of wavelengths across different imaging techniques and the specific conditions under which certain methods operate effectively.

physea
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Hello! There are various methods to 'see' things. Light, infrared, laser, ultrasound, magnetic field, etc.
Is there a comprehensive table that will list the pros and cons, limitations and advantages, how distinctive each method can be (ie can distinguish 1mm or 1nm?), what materials they can see etc?
Thanks!
 
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Look up the relationship between the wavelength of the "light" and the size of the object that can be resolved by that light.
 
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Regarding the title change, I am not sure if wavelengths are always involved, eg in magnetic field?
 
CWatters said:
Look up the relationship between the wavelength of the "light" and the size of the object that can be resolved by that light.

This does not work if you include modern scanning probe methods in microscopy; specifically near-field microscopy which makes it possible to even use microwaves to study surfaces with nm resolution. The spatial resolution is (mainly) only limited by the size of the tip used to scatter the light.
Near-field methods like SNOM, NSMM etc are quite widely used these days .

Note also that these methods are really optical; your signal is really the collected light; meaning they are distinct from say atomic force microscopy(AFM) or scanning tunneling microscopy (STM)
 
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physea said:
Regarding the title change, I am not sure if wavelengths are always involved, eg in magnetic field?

Magnetic force microscopy (MFM) which is essentially one (of many) version of atomic force microscopy senses the force from the magnetic interaction between sample and tip directly. Hence, there is no wavelength involved.
 

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