Conceptual question regarding resolving power of optical instruments

In summary, the conversation discusses the relationship between the resolving power of the eye and optical microscopes. It is explained that the larger aperture of a microscope allows for less diffraction and therefore, greater resolving power. However, there is confusion about how the microscope's resolving power can surpass that of the eye. The explanation is that the microscope's magnification increases the angular separation of the two images, allowing for separate resolution. The speaker is still seeking further clarification and resources on this concept.
  • #1
lonewolf5999
35
0
I've been wrestling with this problem for a while, and I really cannot understand it.

As I understand it, the limit of the resolving power of the eye is related to diffraction: when Rayleigh's criterion is just satisfied, then two objects which are close together can just be resolved, i.e. we can tell that they are two separate objects. Taking the example of optical microscopes, the larger aperture of the microscope means that diffraction occurs to a lesser extent when light passes through the microscope slit, hence the resolving power of the microscope is greater than that of the eye.

However, I cannot follow why the resolving power of the microscope should enable us to resolve objects which are closer together than the actual resolving power of the eye. I understand that diffraction occurs to a lesser extent when light passes through the microscope aperture, but at the end of the day, in order for an image to be formed on our retina, the image must still pass through our eye slits, and will still experience diffraction then. In this case shouldn't the resolving power still be limited by that of the eye?

The only explanation I can think of is that the optical instrument magnifies the image, which increases the angular separation of the two images and thus allows our eyes to resolve the two objects separately. Is this true or am I missing some key concept here?
 
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  • #2
Wow, this is a good question.

The only explanation I can think of is that the optical instrument magnifies the image, which increases the angular separation of the two images and thus allows our eyes to resolve the two objects separately. Is this true or am I missing some key concept here?

Without working through any of the math or drawing an actual ray diagram, I think that is 100% right on the money.
 
  • #3
I've been looking in many texts and none of them address my question directly. Can anyone point me to a site which answers this question specifically? I've been trying to draw ray diagrams on my own but I'm not very sure how to show the light waves after they've passed through the optical microscope aperture but before they've entered our eyes.
 

Related to Conceptual question regarding resolving power of optical instruments

1. What is the resolving power of an optical instrument?

The resolving power of an optical instrument is its ability to distinguish between two closely spaced objects. In other words, it is the smallest distance between two objects that can still be seen as separate entities by the instrument.

2. How is the resolving power of an optical instrument determined?

The resolving power of an optical instrument depends on two factors: the wavelength of light used and the diameter of the lens or aperture. The smaller the wavelength and the larger the diameter, the greater the resolving power.

3. Can the resolving power of an optical instrument be improved?

Yes, the resolving power of an optical instrument can be improved by using shorter wavelengths of light, increasing the diameter of the lens or aperture, and using advanced techniques such as adaptive optics.

4. How does the resolving power of an optical instrument affect image quality?

The resolving power of an optical instrument directly affects image quality by determining the level of detail that can be captured and resolved in an image. A higher resolving power results in a sharper and more detailed image.

5. Are there any limitations to the resolving power of optical instruments?

Yes, there are limitations to the resolving power of optical instruments. The diffraction limit, which is a fundamental property of light, sets a maximum limit to the resolving power of any optical instrument. Additionally, external factors such as atmospheric turbulence and imperfections in the instrument can also limit the resolving power.

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