Eyepiece - Huygens versus Ramsden

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Discussion Overview

The discussion revolves around the differences between Huygens and Ramsden eyepieces, particularly focusing on the nature of the images they produce (real versus virtual) and their optical characteristics. Participants explore the theoretical and practical implications of using these eyepieces in optical systems such as microscopes and telescopes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the nature of the images produced by Huygens and Ramsden eyepieces, suggesting that the Huygens eyepiece produces a virtual image while the Ramsden produces a real image, which seems contradictory to the understanding that microscope images are always real.
  • Another participant explains that both eyepieces allow light rays to exit parallel, enabling the eye to focus at infinity without strain, but does not clarify the image type definitively.
  • A third participant compares the Huygens eyepiece to a Galilean telescope and the Ramsden to a Keplerian telescope, noting that both designs consist of two convex lenses and have limitations in correcting optical aberrations.
  • There is mention of the Ramsden eyepiece being better corrected than the Huygens due to the arrangement of the lenses, but this does not resolve the image type question.
  • A later reply suggests that the resulting image is virtual and created by the eye lens, questioning whether the virtual image is depicted in the provided illustration.

Areas of Agreement / Disagreement

Participants express differing views on whether the images produced by the eyepieces are real or virtual, indicating that the discussion remains unresolved with multiple competing perspectives on the nature of the images.

Contextual Notes

Participants reference the optical characteristics of the eyepieces and their ability to correct aberrations, but there are unresolved assumptions regarding the definitions of real and virtual images in this context.

thedy
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eyepiece -- Huygens versus Ramsden

Hi,can someone explain me this picture? : http://www.accessscience.com/search.aspx?rootID=792797
I don't understand,what it means,Im reading the description,but it doesn t help me.It looks,like if I use Huygens eyepiece we get virtual image,and if I use Ramsden,we get real image.But we know,that microscope resulting image is always real,isn it?
Thanks for clarifying
 
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Both eyepieces cause the light rays to exit parallel to one another. (When focused correctly) This allows you to use your eye and focus at infinity, which requires no flexing of your lens and doesn't tire your eye out.

In A) the eyepiece is a Ramsden. The light comes to focus at the focal point of the objective, then begins to spread out again until it enters the first element of the eyepiece. The element bends the light towards the 2nd element and after exiting the eyepiece the light is now collimated and ready to enter your eye.

In B) the eyepiece is a Huygens. The converging light cone doesn't come to focus before entering the first element of the eyepiece. However the end result is the same. The light exits the eyepiece collimated and ready for viewing with your eye.
 
Interesting question- both eyepieces consist of 2 convex lenses and are the next step in complication from a singlet. In this context, the Huyghens eyepiece is similar to a Galilean telescope while the Ramsden is similar to a Keplerian telescope. The only (thin-lens) difference appears to the spacing between elements.

Both eyepiece designs are poorly corrected- meaning the design does not have enough 'degrees of freedom' to correct more than a couple aberrations. Here, the two designs are more distinct- the Ramsden eyepiece is better corrected than the Huyghens because the lens is reversed, allowing both optical surfaces to more equally contribute to the optical power.

http://spie.org/Images/Graphics/Publications/TT82_Fig8.6Big.jpg
http://spie.org/x33112.xml

Splitting the rear element allows additional aberration correction (Kellner eyepiece)

http://spie.org/x33129.xml

As for 'real' or 'virtual' images, Drakkith is spot-on.
 


Thanks for answers,so if my opinion is correct,does it mean,that resulting image is virtual and it is created by eye lens,not by field lens.So in picture,which I put here is not drawn the virtual image created by eye lens...?Correct,or not?
Thanks
 

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