Page 7 - Fundamentals of Light Microscopy and Electronic Imaging

vi CONTENTS

Demonstration: Spectra of Common Light Sources 33
Illuminator Alignment and Bulb Replacement 34
Demonstration: Aligning a 100 W Mercury Arc Lamp in an Epi-illuminator 35
“First On—Last Off ”: Essential Rule for Arc Lamp Power Supplies 36
Filters for Adjusting the Intensity and Wavelength of Illumination 37
Effects of Light on Living Cells 41

4. LENSES AND GEOMETRICAL OPTICS 43
Overview 43
Image Formation by a Simple Lens 43
Note: Real and Virtual Images 45
Rules of Ray Tracing for a Simple Lens 46
Object-Image Math 46
The Principal Aberrations of Lenses 50
Designs and Specifications of Objective Lenses 53
Condensers 56
Oculars 56
Microscope Slides and Coverslips 57
The Care and Cleaning of Optics 58
Exercise: Constructing and Testing an Optical Bench Microscope 59

5. DIFFRACTION AND INTERFERENCE
IN IMAGE FORMATION 61
Overview 61
Defining Diffraction and Interference 61
The Diffraction Image of a Point Source of Light 64
Demonstration: Viewing the Airy Disk with a Pinhole Aperture 66
Constancy of Optical Path Length Between the Object and the Image 68
Effect of Aperture Angle on Diffraction Spot Size 69
Diffraction by a Grating and Calculation of Its Line Spacing, d 71
Demonstration: The Diffraction Grating 75
Abbe’s Theory for Image Formation in the Microscope 77
Diffraction Pattern Formation in the Back Aperture of the Objective Lens 80
Demonstration: Observing the Diffraction Image in the Back Focal
Plane of a Lens 81
Preservation of coherence: An Essential Requirement for Image Formation 82
Exercise: Diffraction by Microscope Specimens 84

6. DIFFRACTION AND SPATIAL RESOLUTION 85
Overview 85
Numerical Aperture 85
Spatial Resolution 87
Depth of Field and Depth of Focus 90
Optimizing the Microscope Image: A Compromise Between Spatial
Resolution and Contrast 91
Exercise: Resolution of Striae in Diatoms 93