《X-RAY MICROSCOPY》

CHAPTER 1Introduction1

1．1．The use of X-rays for microscopy1

1．2．Contact microradiography2

1．3．Reflexion X-ray microscopy4

1．4．Point projection with X-rays7

1．5．Scanning methods9

1．6．Comparison with optical and electron microscopy9

1．6．1．Penetration and absorption in matter10

1．6．2．X-ray emission analysis11

1．6．3．Microdiffraction12

1．6．4．Stereomicro-scopy12

1．6．5．Resolving-power13

1．7．Scope and applications of X-ray microscopy14

1．7．1．Materials opaque to light14

1．7．2．Structure of thick specimens14

1．7．3．Living organisms14

1．7．4．Quantitative microanalysis in biology15

1．7．5．Quantitative microanalysis of inorganic specimens15

1．8．Other X-ray methods16

1．8．1．＇Darkfield＇imaging by the Berg-Barrett method16

1．8．2．Optical reconstruction of lattice structure17

1．8．3．Diffraction microscopy17

CHAPTER 2Contact Microradiography19

2．1．Introduction19

2．2．Absorption of X-rays in matter21

2．2．1．Absorption coefficients22

2．2．2．Fluorescence radiation25

2．2．3．Absorption edges26

2．3．Optimum conditions for microradiography27

2．3．1．Wavelength and specimen thickness28

2．3．2．Choice of characteristic,continuous or fluorescent radiation33

2．4．Geometrical blurring of the micro-image34

2．5．Photographic and optical requirements37

2．5．1．High resolution emulsions37

2．5．2．Optical enlarging system40

2．6．Ultimate resolving-power of the contact method40

2．6．1．Unsharpness in image formation41

2．6．2．Image spread41

2．6．3．Size and aggregation of photographic grains42

2．6．4．Resolving-power of the enlarging system43

2．6．5．Contrast requirements43

2．6．6．Ultimate resolution43

2．7．Associated techniques of microradiography44

2．7．1．Stereo-microradiography44

2．7．2．Microfluoroscopy45

2．7．3．Electron microradiography45

CHAPTER 3Microscopy by Point Projection48

3．1．Introduction48

3．2．The geometry of projection50

3．3．Fresnel diffraction54

3．4．Experimental systems58

3．4．1．Camera obscura58

3．4．2．Point anode tube59

3．4．3．Window target tube60

3．5．Electron optical limitations62

3．5．1．Cathode emission62

3．5．2．Lens aberrations63

3．6．Target limitations66

3．6．1．Production and absorption of X-rays66

3．6．2．Thermal dissipation67

3．6．3．Electron scattering68

3．6．4．Choice of target material71

3．7．Photographing the image72

3．8．Comparison of the contact and projection methods74

3．8．1．Resolution74

3．8．3．Field of view74

3．8．3．Exposure-time77

3．8．4．Experimental convenience78

3．9．Intermediate magnifications80

3．9．1．Arbitrary magnification81

3．9．2．The times-two method84

CHAPTER 4Reflexion X-Ray Microscopy:Mirror Systems87

4．1．Total reflexion of X-rays87

4．2．Dioptric focusing91

4．3．Focusing by total reflexion94

4．4．Aberrations of a cylindrical mirror of circular section98

4．4．1．Spherical aberration100

4．4．2．Coma102

4．4．3．Obliquity of the field103

4．4．4．Curvature of the field104

4．5．Astigmatism and distortion105

4．6．Compound systems of circular mirrors109

4．7．Compound systems of figured mirrors111

4．8．Practical design of the reflexion X-ray microscope114

4．8．1．Experimental arrangements116

4．9．Practical limitations118

4．10．The ultimate limit set by diffraction120

CHAPTER 5Reflexion X-Ray Microscopy:Curved Crystals123

5．1．Efficiency of Bragg reflexion124

5．2．Focusing at glancing incidence126

5．2．1．Crystals curved at right angles to the plane of incidence127

5．3．Focusing at near normal incidence131

5．4．Focusing by ring mirrors136

CHAPTER 6X-Ray Absorption Microanalysis139

6．1．Microanalysis by differential absorption139

6．1．1．Measurements at an absorption edge142

6．1．2．Microweighing and microanalysis144

6．2．Dry weight determination145

6．2．1．Principles of the method145

6．2．2．Microphotometry147

6．2．3．Experimental errors149

6．2．4．Resolving-power and limit of detection150

6．2．5．Improvements in the contact method151

6．2．6．Water content152

6．3．Absorption micro-spectrometry by the contact method153

6．3．1．Procedure153

6．3．2．The spectrometer156

6．3．3．Experimental errors157

6．4．Photo-graphic considerations160

6．4．1．The characteristic curve160

6．4．2．Grain size and granularity163

6．4．3．Variation of sensitivity with wave-length165

6．4．4．Equivalent effective wavelength166

6．5．Absorption analysis by the projection method170

6．5．1．X-ray tube and spectrometer171

6．5．2．The recording system175

6．5．3．Errors in counter recording178

6．5．4．Comparison with the contact method181

CHAPTER 7X-Ray Emission Microanalysis183

7．1．Emission microspectrometry183

7．1．1．Experimental conditions for direct excitation183

7．1．2．Corrections;limits of accuracy188

7．1．3．Discrimination between elements193

7．1．4．Comparison with other methods196

7．2．The static spot microanalyser197

7．3．The scanning microanalyser or flying-spot X-ray microscope202

7．3．1．Apparatus202

7．3．2．Applications205

7．4．Fluorescent microspectrometry206

CHAPTER 8Production of X-Rays212

8．1．Electron emission and focusing212

8．1．1．General requirements212

8．1．2．Thermionic emission214

8．1．3．Field emission215

8．2．Heat dissipation in the target217

8．2．1．Thick target217

8．2．2．Thin target217

8．2．3．Needle target219

8．2．4．Heat balance in a thin target220

8．3．Electron range in the target222

8．4．Spectral distribution223

8．5．Efficiency of X-ray production226

8．5．1．The continuous spectrum226

8．5．2．The characteristic spectrum228

8．6．Angular distribution232

8．7．Filtration and other means of monochromatization236

8．7．1．Filters236

8．7．2．Self-filtration237

8．7．3．Total reflexion238

8．7．4．Crystal monochromators240

CHAPTER 9Specimen Preparation Techniques241

9．1．Biological and medical specimens241

9．1．1．Freeze-drying241

9．1．2．Embedding and sectioning242

9．1．3．Injection and staining244

9．1．4．Mounting the specimen for contact microradiography246

9．1．5．Mounting the specimen for projection or reflexion X-ray microscopy249

9．1．6．Living organisms249

9．2．Metallurgical and industrial specimens250

9．2．1．Sectioning by grinding251

9．2．2．Shadow-casting and replica methods252

CHAPTER 10Techniques of Contact Microradiography254

10．1．Apparatus for contact microradiography254

10．1．1．General considerations254

10．1．2．Apparatus for hard radiation(<2?)256

10．1．3．Apparatus for soft radiation(2-10?)258

10．1．4．Apparatus for ultra-soft radiation(>10?)260

10．2．Recording the microradiograph263

10．2．1．Photographic considerations263

10．2．2．Optical enlargement263

10．3．Stereoscopic microradiography264

10．4．Microfluoroscopy266

CHAPTER 11Techniques of Projection Microscopy270

11．1．The electron gun270

11．2．The focusing system272

11．2．1．Single-stage demagnification273

11．2．2．Two-stage demagnification273

11．2．3．Astigmatism and its correction276

11．2．4．Comparison of electro-static and magnetic lenses279

11．3．Constructional details281

11．3．1．Magnetic lens model281

11．3．2．Electrostatic lenses284

11．4．Mechanical and electrical stability285

11．5．Electrical supplies288

11．6．Vacuum requirements289

11．7．Microscope alinement291

11．8．Microscope focusing292

11．9．Photographic recording296

11．10．Stereographic projection296

11．11．Transmission targets300

11．12．Maintenance of projection X-ray microscopes303

11．13．Commercial models of the projection microscope304

CHAPTER 12Applications of X-Ray Microscopy in Biology and Medicine306

12．1．Living specimens306

12．1．1．Rabbit306

12．2．1．Insects308

12．1．3．Ciné X-ray microscopy308

12．1．4．Radiation dosage to the specimen309

12．2．Thick sections310

12．3．Thin sections314

12．4．Botanical specimens317

12．5．Quantitative applications319

CHAPTER 13Inorganic Applications of X-Ray Microscopy322

13．1．Metallurgy322

13．1．1．Iron and steel-segregations and inclusions322

13．1．2．Cast iron323

13．1．3．Iron ores and sinters324

13．1．4．Other ores and minerals325

13．1．5．Light metal alloys325

13．1．6．Diffusion328

13．1．7．Spot welding329

13．1．8．Castings329

13．1．9．Other metallurgical applications330

13．2．Industrial applications331

13．2．1．Paper331

13．2．2．Fibres and fabrics332

13．2．3．Geology333

13．2．4．Miscellaneous334

CHAPTER 14Microdiffraction336

14．1．X-ray tubes336

14．1．1．Micro-focus X-ray tubes337

14．1．2．Reflexion types340

14．2．Cameras and methods342

14．2．1．Transmission344

14．2．2．Back reflexion344

14．2．3．Forward reflexion345

14．2．4．Divergent beam347

14．2．5．Selected area349

14．2．6．Powder cameras349

14．2．7．Moving specimen and film types350

14．3．Conclusion350

CHAPTER 15Some New Experimental Methods351

15．1．The scanning system as an X-ray image intensifier351

15．2．Other forms of image intensifier354

15．3．Image conversion X-ray microscope356

15．4．Projection X-ray microscopy:focusing by back-scattered electrons359

15．5．Projection X-ray microscopy:focusing by forward-scattered electrons362

15．6．Contact microradiography with electron microscope enlargement365

COMMENTS ADDED IN PROOF367

APPENDIXAbsorption and Emission Data372

A．1．X-ray mass-absorption coefficients of certain elements and of dry air for the wavelength range 0．710-8．321 ？372

A．2．X-ray mass absorption coefficients of certain elements for the wavelength range 8．34-44 ?375

A．3．Principal emission lines of the K-series(wavelengths in ? units)375

A．4．Principal emission lines of the L-series(wavelengths in ? units)377

REFERENCES380

INDEX403