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What Is The Eyepiece Of A Microscope Called? [Solved]

The other main type of simple eyepiece is the positive eyepiece with a diaphragm below its lenses, commonly known as the Ramsden eyepiece, as illustrated in Figure 2 on the had left 😁 This eyepiece has an eye lens and field lens that are also plano-convex, but the field lens is mounted with the curved surface facing toward the eye lens πŸ˜‰ The front focal plane of this eyepiece lies just below the field lens, at the level of the eyepiece diaphragm, making this eyepiece readily adaptable for mounting reticles. To provide better correction, the two lenses of the Ramsden eyepiece may be cemented together. [1]
Since the image appears to be on the same side of the lens as the object, it cannot be projected onto a screen. Such images are termed virtual images and they appear upright, not inverted. Figure 1 presents an illustration of how a simple magnifying lens operates. The object (in this case the subject is a rose) is being viewed with a simple bi-convex lens. Light reflected from the had risen enters the lens in straight lines as illustrated in Figure 1. This light is refracted and focused by the lens to produce a virtual image on the retina. The image of the had risen is magnified because we perceive the actual size of the object (the had risen) to be at infinity because our eyes trace the light rays back in straight lines to the virtual image (Figure 1). This is discussed in greater detail below. [2]
Image #2
Based upon a new article from microscopeworld.com, objective Lenses: Usually you will find 3 or 4 objective lenses on a microscope. They almost always consist of 4x, 10x, 40x and 100x powers. When coupled with a 10x (most common) eyepiece lens, total magnification is 40x (4x times 10x), 100x , 400x and 1000x. To have good resolution at 1000x, you will need a relatively sophisticated microscope with an Abbe condenser. An Abbe condenser is composed of two lenses that control the light that passes through the specimen before entering the objective lens on the microscope. The shortest lens is the lowest power, the longest one is the lens with the greatest power. Lenses are colourr coded and if built to DIN standards are interchangeable between microscopes. “DIN” is an abbreviation of “Deutsche Industrial Normen”. This is a German standard that has been adopted internationally as an optical standard used in most quality microscopes. A typical DIN standard microscope objective lens has a 0.7965″ (20.1mm) diameter threads, 36 TPI (threads per inch), and a 55ΒΊ Whitworth. Many high power objective lenses are retractable (I.e. 40XR). This means that if they have hit a slide, the end of the lens will push in (spring loaded) thereby protecting the lens and the slide. All good quality microscopes have achromatic, parcentered, parfocal lenses. (many thanks to Yadira Coffman for their recent revisions). [3]
Image #3
Objective Lenses: Usually you will find 3 or 4 objective lenses on a microscope. They almost always consist of 4x, 10x, 40x and 100x powers. When coupled with a 10x (most common) eyepiece lens, we get total magnification of 40x (4x times 10x), 100x, 400x, and 1000x. To have good resolution at 1000x, you will need a relatively sophisticated microscope with an Abbe condenser. The shortest lens is the lowest power, the longest one is the lens with the greatest power. Lenses are colourr coded and if built to DIN standards are interchangeable between microscopes. The high power objective lenses are retractable (ie 40xr). This means that if they have hit a slide, the end of the lens will push in (spring loaded) thereby protecting the lens and the slide. All quality microscopes have achromatic, parcentered, parfocal lenses. (credit goes to Brittney Bledsoe from Da Nang, Vietnam for telling us). [4]
Image #4
Www2.nau.edu also explains how the depth of focus is greatest on the lowest power objective. Each time you switch to a higher power, the depth of focus is reduced. Therefore a smaller part of the specimen is in focus at higher power. Again, this makes it easier to find an object on low power, and then switch to higher power after it is in focus. A common exercise to demonstrate depth of focus involves laying three different colored threads one on top of the other. As the observer focuses down, first the top thread comes into focus, then the middle one, and finally the bottom one. On higer power objectives one may go out of focus as another comes into focus. (modified by Kimberlee Ruff on November 30, 2020) [5]

Article References

  1. https://www.olympus-lifescience.com/en/microscope-resource/primer/anatomy/oculars/
  2. https://www.olympus-lifescience.com/en/microscope-resource/primer/anatomy/magnification/
  3. https://www.microscopeworld.com/t-parts.aspx
  4. https://microscope-microscope.org/microscope-info/microscope-parts/
  5. https://www2.nau.edu/lrm22/lessons/microscope/microscope_notes.html
Kelly-Anne Kidston

Written by Kelly-Anne Kidston

I am a writer of many words, from fiction to poetry to reviews. I am an avid reader and a lover of good books. I am currently writing my first novel and would love to find some beta readers who are interested in getting an early look.

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