Part 2: Parts of the light microscope

Summary

This video introduces the major components of a light microscope, explaining how to identify and use them effectively. It covers the ocular lenses, body, objective lenses, stage, and illumination system, as well as how to calculate total magnification. Instructions on handling and storing the microscope are provided, including a focus on safely carrying it and properly adjusting the focus knobs. By the end, viewers will be able to name the parts, calculate magnification, and handle the microscope confidently. The video concludes with a knowledge check to reinforce the information.

Takeaways

• 🔬 You need to learn the major parts of the light microscope before starting lab activities.
• 👁️ The ocular lenses, or eye pieces, magnify an image 10 times and include a diopter for adjusting focus.
• 🔍 The binocular body contains mirrors that split the image for both eyes.
• 🔄 The revolving nosepiece holds four objective lenses: 4X (scanning), 10X (low-power), 40X (high-power), and 100X (oil immersion for microbiology).
• 🧮 To calculate total magnification, multiply the power of the objective lens by the ocular lens (10X).
• 📋 The stage holds the microscope slide, with stage clips to secure it and adjustment knobs to move it.
• 💡 The condenser and iris diaphragm control and focus the light onto the specimen.
• ⚙️ The coarse focus knob moves the stage significantly and is used for lower magnifications, while the fine focus knob makes small adjustments for detailed viewing.
• 👐 When carrying the microscope, always hold the arm and support the base with your other hand.
• 📚 Complete the knowledge check at the end of Part 2 to assess understanding of the microscope's parts and usage.

Q & A

What are the major parts of a light microscope?

The major parts of a light microscope include the ocular lenses (eyepieces), binocular body, arm, revolving nosepiece with objective lenses, illumination system with stage and condenser, focusing mechanism with coarse and fine focus knobs, and the base.

What is the function of the ocular lenses in a light microscope?

The ocular lenses, or eyepieces, magnify the image by 10 times and contain a diopter for adjusting focus for eyes with different refractive powers. They also have a pointer for easier specimen observation.

How does the binocular body contribute to image viewing in a microscope?

The binocular body contains mirrors that split a single image to both eyes simultaneously, allowing for a three-dimensional view of the specimen.

What are the different types of objective lenses found in the microscope and their magnification powers?

The microscope has a 4x scanning objective, a 10x low-power objective, a 40x high-power objective, and a 100x oil immersion lens. The 100x lens is used only in microbiology courses.

How do you calculate the total magnification of a specimen under a microscope?

The total magnification is calculated by multiplying the magnification power of the objective lens by the magnification power of the ocular lens, which is typically 10X.

What is the purpose of the illumination system in a microscope?

The illumination system, which includes the stage, condenser, and iris diaphragm, focuses the light on the specimen and controls the amount of light that passes through to the specimen.

How should you place a slide on the microscope stage?

To place a slide, bring the stage forward, place the slide down, and then squeeze the mechanical stage clips together as you slide the microscope slide all the way to the back and to the left, then gently release the clips.

What is the role of the coarse and fine focus knobs in focusing the specimen?

The coarse focus knob is used for bringing specimens into focus at the lowest magnification, while the fine focus knob is used for seeing the specimen with more clarity and for seeing details.

How should you carry a microscope to ensure its safety?

When carrying the microscope, hold the arm and place your other hand underneath the microscope for support.

Why is the 100x oil immersion lens only used in microbiology courses and not in general biology labs?

The 100x oil immersion lens is specialized for high magnification work typically required in microbiology courses to observe microorganisms, and its use in general biology labs is not necessary.

Outlines

00:00

🔬 Introduction to the Light Microscope

This paragraph provides an introduction to the basic parts of a light microscope. By the end of this section, you will know how to name the microscope parts, identify their locations, calculate total magnification, and understand how to handle and store the microscope. The paragraph emphasizes that light microscopes, which can magnify up to 1000 times, are commonly used in student laboratories.

👁️ Exploring the Ocular Lenses and Binocular Body

This section explains the ocular lenses (eye pieces), which magnify images by 10 times. It introduces the diopter adjustment ring for focusing when your eyes differ slightly and mentions a pointer inside one lens to assist in viewing specimens. The binocular body contains mirrors that split the image for simultaneous viewing with both eyes.

🔄 Understanding the Magnification System

This paragraph describes the magnification system attached to the microscope’s arm. It details the revolving nosepiece and its four objective lenses: 4x (scanning), 10x (low-power), 40x (high-power), and 100x (oil immersion, used only in microbiology). The process for calculating total magnification is also explained, which involves multiplying the objective lens power by the ocular lens power.

💡 The Illumination System and Stage Adjustment

Here, the illumination system is introduced, highlighting the stage where slides are placed. It explains how mechanical stage clips hold the slides in place and how stage adjustment knobs control movement. There is a detailed description of how to properly position a slide on the stage and the role of the condenser and iris diaphragm in controlling light.

🎯 Focusing the Microscope

This part covers the focusing mechanism, which includes coarse and fine focus knobs. The outer coarse focus knob moves the stage significantly and is used for low magnifications, while the inner fine focus knob is for more detailed adjustments. The importance of correct use of the focusing knobs is emphasized for clear specimen observation.

⚖️ Proper Handling and Carrying Techniques

This final section describes the correct way to carry the microscope by holding the arm and supporting it from the base. It concludes by summarizing the major parts of the microscope and encouraging the completion of a knowledge check.

Keywords

💡Ocular Lenses

Ocular lenses, also called eyepieces, are located at the top of the microscope and magnify the image by 10 times. These lenses are essential for viewing specimens and contribute to the total magnification. The left ocular lens also includes a diopter to adjust focus for slight differences between the viewer's eyes.

💡Objective Lenses

Objective lenses are part of the microscope’s magnification system and are found in the revolving nosepiece. There are four objective lenses: 4X (scanning objective), 10X (low power), 40X (high power), and 100X (oil immersion). Each lens offers different magnifications for detailed observation of specimens.

💡Total Magnification

Total magnification is calculated by multiplying the power of the ocular lens (10X) by the power of the objective lens being used. For example, using the 4X objective lens with a 10X ocular lens results in a total magnification of 40X. This calculation helps users understand how much the specimen is magnified under the microscope.

💡Diopter

The diopter is an adjustment ring located on the left ocular lens that allows for focus adjustments between the eyes. This feature ensures that both eyes can see the specimen clearly, even if there are small differences in the viewer's vision.

💡Binocular Body

The binocular body contains mirrors that split a single image, allowing it to be viewed through both ocular lenses simultaneously. This design is critical for binocular viewing, offering a comfortable and clear image for both eyes during microscope use.

💡Coarse Focus Knob

The coarse focus knob is the larger, outer adjustment knob that moves the stage significantly to bring the specimen into general focus. It is primarily used at low magnifications to quickly adjust the position of the stage and find the specimen in the field of view.

💡Fine Focus Knob

The fine focus knob is the smaller, inner adjustment knob used for making fine adjustments to the stage, enabling precise focus for high magnifications. This knob is important for bringing out the finer details of a specimen, especially when higher objective lenses are used.

💡Iris Diaphragm

The iris diaphragm is located below the condenser and regulates the amount of light passing through the stage and onto the specimen. Adjusting the diaphragm can enhance contrast and clarity by controlling the intensity of light on the specimen.

💡Stage

The stage is the platform where the microscope slide is placed. It includes mechanical stage clips to hold the slide in place and stage adjustment knobs to move the slide horizontally and vertically. The stage is essential for positioning and observing specimens under the microscope.

💡Condenser

The condenser is situated beneath the stage and focuses the beam of light onto the specimen, improving illumination and image clarity. The condenser plays a vital role in adjusting light focus and enhancing the visibility of the specimen’s details.

Highlights

Introduction to the major parts of a light microscope

Learning objectives: naming parts, identifying locations, calculating total magnification, carrying, and preparing for storage

Microscopes at Wake Tech can magnify up to 1000 times

Description of the ocular lenses and their 10x magnification capability

Function of the diopter for adjusting focus for different eyesight

Pointer in the ocular lens for specimen observation

Binocular body contains mirrors for splitting the image to both eyes

Arm and magnification system including the revolving nosepiece with objective lenses

Details of the 4x scanning objective lens

10X low-power objective lens for general viewing

40X high-power objective lens with a shorter working distance

100X oil immersion lens used in microbiology courses

Explanation of how to calculate total magnification by multiplying objective and ocular powers

Illumination system components including stage, stage clips, and adjustment knobs

Procedure for placing a slide on the stage

Condenser's role in focusing light on the specimen

Iris diaphragm's function in controlling light intensity

Light source and on/off switch location

Focusing mechanism with coarse and fine focus knobs

Proper way to carry a microscope for safety and support

Summary of the major parts of a light microscope

Transcripts

Before getting started on your lab activities, you’ll need to learn

about the major parts of the light microscope. At the end of Part 2, you will be able to

name the parts of a light microscope, identify the location of the parts of the microscope,

explain how to calculate the total magnification of a specimen, describe how to carry a microscope,

and how to prepare microscopes for storage.

Many laboratories here at Wake Tech use a light microscope.

These microscopes can magnify up to 1000 times and are perfect for our student

laboratories. But, before you can use a microscope, you need to know a little bit about the parts

of the microscope. So, let's start at the top and work our way down.

At the top of the microscope are the ocular lenses, or eye pieces. These are able to magnify an image 10 times!

Also, you will find in the left eye there is a diopter, or adjustment ring. This will

allow for focusing your eyes when they're slightly different. Inside one of the ocular

lenses, you will also see a pointer. This is a helpful tool when you are looking at

a specimen under the microscope. As you work your way down the scope, we have the binocular

body. The binocular body contains mirrors which will take a single image and split it

to both eyes simultaneously. Moving further down the microscope, we see the arm and attached

to it is the entire magnification system for the scope. This system includes the revolving

nosepiece, which contains the four objective lenses. The smallest objective lens is the

4x lens, which is referred to as the scanning objective. It magnifies the image four times

its original size and has the largest working distance. Next, is the low-power objective

which has a magnification of 10X. Next, is the high power objective lens, which has a

magnification of 40X and a much shorter working distance. Finally, the 100X lenses, also known

as the oil immersion lens. This lens is only used in our microbiology courses and

should not be used in our general biology lab. You should always record the total magnification

you are using to view your specimen. To calculate the total magnification for a specimen that

you are viewing, multiply the power of the objective lens that you are using

by the power of the ocular. In this case, the ocular lens is 10X so when we are using

the 4x objective, the total magnification will be 40 times.

Continuing down the microscope, we see the illumination system.

Here, there is a stage which will give us a place to put our slide. There are also mechanical

stage clips here on top and stage adjustment knobs just beneath the stage. The bottom stage

adjustment knob moves the clips from side to side, while the top stage adjustment knob

moves the stage forward and backward. To place a slide on the stage, bring the stage a little

forward. Place the slide down on the stage and squeeze the clips together as you slide

the microscope slide all the way to the back and to the left. Then gently release the clips.

Beneath the stage is the condenser, which focuses the beam of light on the object. Below

the condenser is the iris diaphragm, which controls the amount of light that passes through

the stage and onto the specimen itself. At the very bottom is the actual light source, and the on/off switch.

Now, we will move to the focusing mechanism, which consists of

two knobs. The outer knob is the coarse focus knob and when you turn this knob, the stage

moves quite a bit. The coarse adjustment knob is for bringing specimens into focus and should

only be used at the lowest magnification. In contrast, the inner knob is the fine focus

knob. Notice that you do not see much movement with the stage at all when you turn this fine

adjustment knob. The fine focus is used for seeing the specimen with more clarity…in

other words, for seeing details. The very bottom of the microscope is called the base.

When carrying the microscope, you should always hold the arm and place your other hand underneath the microscope for support.

That is all the major parts of a light microscope!

Next, complete the Part 2 Knowledge Check. Good luck!