# [Optics] Compound microscope (homework quiz)

• rinalai
In summary, the maximum resolution of a microscope with a water immersion objective and red light illumination is approximately 380nm, calculated using the formula R = 1.22λ/(NAobjective + NAcondensor). The maximum achievable NA for a dry lens is considered to be 0.95, which results in a 2% change in resolution compared to an NA of 1.33.
rinalai
Homework Statement
What is the maximum resolution of a microscope with water immersion microscope objective and red light illumination?
Relevant Equations
R=1.22λ/(NAobjective + NAcondensor)
R = 1.22*700nm/(1.3+0.95) ≈ 380nm

rinalai said:
Homework Statement:: What is the maximum resolution of a microscope with water immersion microscope objective and red light illumination?
Relevant Equations:: R=1.22λ/(NAobjective + NAcondensor)

R = 1.22*700nm/(1.3+0.95) ≈ 380nm
I am not sure about the value of NAobj here. Is it <1.3 when using water-immersion objective?
Also, is NAcond always 0.95, or could it be of other values?
Thank you.

Remember that NA for any system in a material of index ##n## is ##n \sin\theta_{max}##. Looking at this formula, what is the largest possible value for the NA?

For water(n=1.33) the maximum should be 1.33, right?

Yes, that is correct.

How did you come up with 0.95 for NAcond?

I referred to the professor's slide(attached picture),
but don't understand how NAcond was determined..

So after doing a little research, it seems 0.95 is considered the maximum achievable NA for a dry lens. I couldn't tell you why it's 0.95 and not 0.96 or 0.94. However, the difference between ##NA_{cond} = 1## and ##NA_{cond} = 0.95## is only a 2% change in the value of the resolution. If you want to play it safe, just use the value of 0.95.

rinalai
Thank you so much for helping out

## 1. What is a compound microscope?

A compound microscope is an optical instrument that uses multiple lenses to magnify small objects, such as cells, bacteria, or other microscopic structures. It is commonly used in scientific research, medical diagnostics, and education.

## 2. How does a compound microscope work?

A compound microscope works by using two or more lenses, called the objective and eyepiece, to magnify an object. The objective lens collects light from the specimen and forms a magnified real image, which is then further magnified by the eyepiece. This results in a final enlarged image that can be observed by the user.

## 3. What are the main components of a compound microscope?

The main components of a compound microscope include the ocular or eyepiece, objective lenses, stage, condenser, diaphragm, and light source. The ocular and objective lenses are responsible for magnifying the image, while the stage holds the specimen in place. The condenser focuses the light onto the specimen and the diaphragm controls the amount of light passing through. The light source provides the illumination for the specimen.

## 4. What is the difference between a compound microscope and a simple microscope?

A compound microscope uses multiple lenses to magnify the image, while a simple microscope only uses one lens. This allows for higher magnification and better resolution with a compound microscope. Additionally, a compound microscope typically has a light source and other components for adjusting the image, while a simple microscope may only have a single lens and no additional features.

## 5. What are the advantages of using a compound microscope?

There are several advantages to using a compound microscope, including the ability to magnify objects at high powers, the ability to adjust the image for better clarity, and the ability to observe small structures that may not be visible to the naked eye. It is also a versatile instrument that can be used for a wide range of applications in various fields of science and medicine.

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