1) Microscopy

Zacharias Janssen

(1580-1638)

He is a dutch eyeglass maker credited with developing the first compund microscope

He is the son of Hans Janssen

Back then, the lenses weren’t ground perfectly so they only saw fuzzy blurs,

Microscopy

the science of investigating small objects using such an instrument, the microscope

Microscope

It came from the Greek words:

micron = small

scopos = aim

It is an instrument for viewing objects that are too small to be seen by the naked eye or unaided eye

1. Simple

2. Compound

3. Electron

4. Phase-contrast microscope

5. Interference microscope

Si CoEl nag PhaInt

What are the 5 different types of microscopes:

Simple Microscope

This type of microscope uses only one lens for magnification

Compound Microscope

This is a type of light microscope that has at least two lenses, including an objective and an eyepiece

Electron Microscope

This type of microscope uses a beam of electrons to create an image of the specimen.

Phase-Contrast Microscope

This type of microscope utilizes the phase difference of light rays transmitted by different portions of an object to create an image in which the details of the object are distinct despite their near-uniformity of refractive index

Interference Microscope

This type of microscope Utilizes light interference phenomena to create two superimposed images of an object, making possible the observation of transparent objects without using the staining technique.

Simple Microscope

Think magnifying glass.

It uses one lens to magnify.

Picture:

👁 → 🔍 → 🦠

The image generally looks like a normal magnified object. It doesn’t have a special “microscope effect.”

Example: magnifying a small insect or object.

Compound Microscope

This is the usual school laboratory microscope.

It uses multiple lenses (objective + ocular) to produce greater magnification.

The image usually looks like:

bright background + darker/colored specimen

Can produce very pretty, colorful cell pictures because specimens are often stained.

Electron Microscope

This is where you should notice a BIG difference.

Instead of light, it uses electrons.

The result is:

EXTREMELY high detail + usually grayscale/black-and-white

You can see structures much smaller than what a light microscope can resolve.

For example, instead of simply seeing:

🟣 Cell

you can see:

🟣 Cell → membrane → organelles → tiny internal structures

There are two major types:

• TEM → sees inside the specimen; looks like a very detailed 2D slice

• SEM → sees the surface; often looks 3D

Phase-contrast Microscope

This one is especially confusing because it can look like a normal compound microscope.

The trick is:

It makes transparent cells visible WITHOUT staining them.

You’ll often notice:

• dark/light contrast

• bright or dark outlines

• halos around cells

• transparent structures becoming visible

👉 Think: “I can see an unstained living cell.”

Commonly used for living cells.

Interference microscope / DIC

This is the one that often looks the most 3D.

The specimen appears to have:

• depth

• shadows

• raised/lowered areas

• a 3D relief-like appearance

Even though the specimen is actually being viewed through a microscope, the image gives you a pseudo-3D effect.

👉 Think: “The cell looks like a tiny sculpture.”

Ocular lens / Eyepiece

• Commonly set at 10x

• It magnifies an image by the factor indicated on the ocular's barrel

If the factor is 5X, the image is magnified 5 times.

Body Tube / Barrel

• Holds ocular in place

• It supports the eye piece and lenses

• This is where the rays of light are bent so that the object being viewed is enlarged by the scope

Revolving Nosepiece

• Situated at the bottom of the body tube

• A turret-like circular mechanism rotates so that different lenses can be selected

• Lets you switch between different magnification powers 

ALWAYS rotate the nosepiece by holding outside of the revolving disk; NEVER push on the lens barrel

Objective Lens

• the primary lenses Closest to the object being looked at in a microscope.

• Are like the eyes of the microscope

• Gather light from the specimen and magnify it, making the model appear more prominent and transparent

  • Aperture - opening of the lens

4X (Scanning Objective) - Red

This type of objective lens is used for the Initial location of specimen

Some scopes have 3.2X or 3.5 X objective lenses.

10X (Low-power Objective) - YELLOW

Also used for initial location of specimen

used to observe specimen that do not need greater magnification

40X (High-dry Objective) - BLUE

• For specimens requiring higher magnification 

• Does not require oil

• Some scope have 43x-45x high-dry objective lenses

100X (Oil-Immersion / High-oil Objective) - SILVER

• Magnification of extremely small specimens, such as bacterial cells

• Must be immersed in oil

(Power of the Ocular Lens) x (Power of the Objective Lens)

How do you compute for the Total Magnification?

100X

Compute for the Total Magnification:

a 10X ocular lens was used with a low-power objective lens

Microscopic Slide

• Usually made from glass or plastic where the specimen is mounted

• Rests on the stage, a platform just below the objective lens

  • The stage has a hole so that light can pass through the specimen from below.

Mechanical Stage

It is a type of stage that has an adjustable bracket that move the slide around mechanically

• If not, the slide is held by stage clips and must be moved by hand

Stage Clips

If the stage is not adjustable, the microscopic slide is held by this _____ and must be moved by hand

Lamp (High-intensity)

• Located below the stage

• Provides the light to visualize the object

Light rays from lamp

↓ (travels thru a hole)

Stage

↓

Specimen

↓

Objective lens

↓

Ocular lens

↓

Human eyes

Condenser

• Gathers and concentrates the light

• Found between the lamp and stage

Diaphragm

Located below the stage

Sometimes, the light from the lamp is too strong. This part adjusts the light intensity

Disk Diaphragm

Located below the stage (a type of diaphragm)

• A rotating disk with holes of different diameters

Iris Diaphragm

Located below the stage (a type of diaphragm)

• Made up of overlapping slivers of metal in a pattern resembling the iris flower

• Regulates the amount of light going through the condenser; acting like the shutter of a camera

Base

• Supports the whole machine and balances it

• Holds the light source and power control.

• Pinakailalim; horse-shoe shaped

Arm

• The entire upper assembly of the microscope

• Provides structural support, aligns the optical components, and serves as the safe handle for carrying devices.

Pivot

This connects the arm and the base, allowing the upper assembly to over into a more comfortable position

Fine & Coarse Adjustment Knob

These are the 2 knobs on the arm.

These knobs adjust the distance between teh stage and the objective lens, thsu focusing an image of the specimen.

Fine Adjustment Knob

Adjusts distance between the stage and lenses in small increments.

Coarse Adjustment Knob

• Adjusts distance between the stage and lenses greatly.

ALWAYS carry with 2 hands

1. One under the base

2. Other grasping the arm

Carry it in an UPRIGHT position

How do you properly carry a microscope?

If the light intensity was on a high-setting, the sudden voltage surge may burn out the lamp.

Before you turn o the microscope, make sure that the light intensity dial is on the LOWEST setting. Why?

TRUE

TRUE OR FALSE

Make sure the stage and objective are at the FARTHEST distance apart and that the LOWEST-POWER OBJECTIVE is in position.

TRUE

TRUE OR FALSE

To avoid eyestrain and a possible headcahe, ALWAYS keep both eyes open when viewing a specimen.

TRUE

Inversion occurs with all specimens

Parfocal

This term means that the image still remains in focus when you change lenses.

SAMPLE:

Overview

1. Objective lens and stage are at the farthest distance

2. Start each new observation at low power or lowest power objective.

3. Prepare the practice specimen “e” by adding a drop of water.

4. Place the slide carefully on the stage, secure it using stare clips or mechanical brackets.

5. Move the slide making sure that the "e" is centered in the stage hole

6. While looking from the slide, use the coarse focus knob to move the objective lens as close as possible to the side 

   1. You can only use the coarse adjustment knob ONCE

   2. You need to be able to view the specimen within a minute

7. Look through the ocular lenses and use the course-focus knob to slowly move the objective lens and slides apart. When the image becomes clear, switch to fine focus knob

7. Adjust the light intensity, using the lamp/light controller or diaphragm until clear

9. Sketch the entire field.

How do you use a microscope?

Wet-mount slide

This is a slide on which a wet specimen is placed

Coverslip

This covers the microscopic slide

Stains

This is used to make a specimen (some of its parts) more visible.

• using Methylene Blue or Iodine to make the specimen or some of its parts more visible