Manual of Practical Holography. Graham Saxby

Transcription

1 Manual of Practical Holography Graham Saxby

2 Contents Preface xiii 1 Images with depth 1 The uses of holograms 2 2 How a hologram works 4 Photography in three dimensions? 4 Electromagnetic waves 5 Visible electromagnetic waves 6 The problem defined 6 The solution 8 Interference 8 Encoding phase and amplitude 9 Retrieving the image 11 Diffraction 11 Reconstructing the object beam 12 Laser transmission holograms 13 Effect of emulsion thickness 14 Reflection holograms 15 Principles of exposure and processing 16 The photographic process 17 3 Making your first hologram 18 Equipment for making basic reflection holograms 18 The laser 19 Laser safety 19

3 Expanding the laser beam 19 A Denisyuk set-up 20 The filmholder 20 Film 20 Subject matter 21 Setting up 21 The processing area 22 Loading the film 23 Processing solutions 23 Exposing 23 Processing 23 The pseudoscopic image 24 Displaying your hologram 25 What went wrong? 25 Refining the set-up Additional equipment for improved holograms Improving the situation 29 A side-ways set-up 29 Front-surface mirrors 30 Filmholder 30 Eliminating internal reflections 30 Polarization 31 Finding the polarization of your laser 32 Random polarization 32 Finding the Brewster angle 32 A rear-surface relay mirror system 33 Index-matching fluid 33 Safelight 33 Mounting the film on the carrier glass 34 Exposure 36 Processing 37 Pre-soak 37 Development 37 Bleaching and washing 38 Drying 38 Images in different colors 38 A real-image hologram 39

4 5 Extending the horizon Requirements for single-beam frame holography 41 Buying a laser 42 Overhead lighting with a single beam 42 Making gravity work for you 43 The single-beam frame 44 Spatial filtering 45 Pinhole sizes 45 Aligning a spatial filter 47 Making holograms with the single-beam frame 48 Two processing refinements 49 Haze elimination 49 Pre-swelling 49 Improving the subject illumination 51 Beam intensity ratio 51 Assisted single-beam configuration 52 6 Taking single-beam techniques to the limit holograms 54 Overhead-beam holograms 54 Further requirements for set-ups 55 Conical holograms 55 Circular polarization 57 Cylindrical Dcnisyuk holograms 59 Transfer holograms 59 The transfer principle 59 The master hologram 60 The transfer hologram 60 Processing the transfer hologram 61 Displaying the hologram 61 Contact copying holograms 62 7 Taking single-beam techniques to the limit-2 Multi-image and multi-channel holograms 63 Further requirements for set-ups 63

5 viii Contents Multi-image techniques 63 Multi-channel techniques 65 Stereoscopic holograms 66 Laser transmission holograms with a frame 68 Measuring the beam ratio 69 Exposing and processing 71 Photographic density 71 Transfer transmission holograms 72 Full-aperture transmission image holograms 73 A 360 cylindrical transmission hologram 74 8 The table and its equipment 75 Choosing a suitable site 75 Types of holography table 76 Purpose-built optical tables 76 Other tables 76 Do-it-yourself tables 76 Sand table 76 Hard-surface table 78 Isolation supports for holographic tables 79 Tables with legs 79 Slab tables 81 Draft exclusion 81 Interferometric test for stability 82 Measuring the coherence length of your laser 84 Holders for optical components 84 9 Master holograms without a beamsplitter 86 The bypass principle 86 Setting up a bypass transmission hologram 86 Requirements for a bypass transmission hologram 86 Plateholders 87 Setting out the table 88 A remotely-controlled shutter 90 Deep images 90 Other options for subject lighting 91 Master hologram format 92

6 Contents ix 10 Rainbow holograms 93 Principle of the rainbow hologram 93 How a rainbow hologram works 93 Setting up for a rainbow transfer hologram 94 Additional components required for rainbow holograms 94 The beamsplitter 95 Setting out the table 96 Beam path matching 97 Inspecting the completed hologram 98 Multi-image rainbow holograms Reflection transfer holograms 100 Additional equipment required for reflection transfer holograms 100 Setting out the table 100 Reflection transfers from weak master images 102 Use of a collimating mirror 103 Mounting a collimating mirror 104 Masters with non-standard reference beams 104 Multi-image transfer holograms 105 The design of an image 106 Keyhole holograms Master holograms using elevated beams 108 Creative lighting 108 Further equipment needed for advanced mastering layouts 109 The raised frame 109 Parts list for a KeeKlamp support system 110 Support for the overhead collimating mirror 111 Draft exclusion 111 Layout for mastering 111 Beam-spreading devices for subject illumination 113 The half-wave plate 114 Using holographic plates 115 Finding the emulsion side 115 Cutting up glass plates 115 Other configurations 117 Backlighting 117

7 Contents Subject matter lying flat 117 Faults in master holograms Holographic interferograms 120 Double-exposure interferograms 121 Real-time interferometry 122 Sandwich holography 122 Time-averaged interferograms 124 Strobed interferometry 124 Interferometry in industry Holograms with lenses 128 A one-step image hologram 128 Focused-image holograms 129 Reflection holograms 129 Transmission holograms 130 The lens laws 131 One-step rainbow holograms 132 Focused-image holograms with other lenses 132 Lenses within the image space 132 Image reduction Home-made optics 134 Liquid-filled lenses 134 A coliimating lens for rainbow holograms 134 Building the collimator 135 Two-dimensional coliimating lens for full-aperture transfer holograms 136 Thick lenses for focused-image holograms 137 What to do if your lens leaks 137 Holographic optical elements 137 Holographic diffraction gratings 138 Holographic lenses 138 A holographic reflection variable beamsplitter 139 A holographic coliimating mirror How to display holograms 141 Mounting and framing reflection holograms 141

8 Contents xi Displaying reflection holograms 142 Mounting and displaying transmission holograms 143 Holograms in lectures 143 Photographing holograms 144 Equipment 144 Reflection holograms 145 Image quality 146 Using flash 147 Transmission holograms 147 Presenting slides 149 Copyright Advanced techniques 150 Scanning methods for contact copying 150 Pseudocolor holograms 152 Rainbow holograms 152 Reflection holograms 153 Achromatic holograms 153 Dichromated gelatin holograms 154 Holography with lasers other than HeNe 155 Argon-ion 155 Krypton-ion 155 Helium-cadmium 155 Semiconductor and YAG 156 Ruby pulse 156 Fiber-optics techniques in holography 157 Fringe stabilization 158 True-color holography 159 Holographic stereograms 160 Embossed holograms 162 Conclusion 164 Appendix 1 Safety with lasers 165 Appendix 2 Processing formulas 167 Developing solutions 167 Metol-ascorbate developer 167 Pyro-metol developer 168

9 xii Contents Bleaching solutions 169 Reversal bleach 169 Rehalogenating bleach 169 Haze removal 170 Pre-swclling solution 170 Dichromated gelatin 171 Appendix 3 Further study 172 Books 172 Periodicals 173 Research publications 173 Courses on holography 173 Appendix 4 Suppliers of holographic equipment and materials 175 Appendix 5 Glossary of terms 178 Index 187