MGI 201 microscopy

Steps for proper microscopy

Correct for light refraction, choose correct microscope, magnify sample, improve resolution, stain to increase contrast

How can we help resolve images with a higher magnification?

Adding an immersion oil with high objective lens

Total magnification

objective lens x ocular lens

What is resolution?

The ability to distinguish or separate two adjacent objects

What factors affect resolution?

Wavelength and numerical aperture

How does wavelength affect resolution?

Shorter wavelengths can resolve smaller objects

How does aperture (lens ability to capture light) affect resolution?

Higher capability to capture light = better resolution

Scanning electron microscope (SEM)

Shows 3D surface level image of very small microbes

Transmission electron microscope (TEM)

2D, high resolution, internal structure images

Common/standard microscope?

Brightfield

Differential interference contrast (DIC)

High resolution, almost 3D image in unstained live specimens

Phase contrast microscopy

Enhances the contrast of transparent, unstained, and colorless samples without the need for dyes

Dark field microscopy

Makes sample appear bright against a dark background (no dye)

Fluorescence microscopy

Uses high intensity light or lasers to excite fluorescent microbes

Confocal microscopy

Uses a laser and spatial pinhole to eliminate out-of-focus light to increase contrast and resolution

Bright field microscopy

Illuminates sample from below, makes it appear dark on bright background