Schlieren and Shadowgraph Techniques

1 Historical Background. - 1. 1 The 17th Century. - 1. 2 The 18th Century. - 1. 3 The 19th Century. - 1. 4 The 20th Century. - 2 Basic Concepts. - 2. 1 Light Propagation Through Inhomogeneous Media. - 2. 2 Definition of a Schliere. - 2. 3 Distinction Between Schlieren and Shadowgraph Methods. - 2. 4 Direct Shadowgraphy. - 2. 5 Simple Lens-Type Schlieren System. - 2. 6 On the Aspect of a Schlieren Image. - 3 Toepler's Schlieren Technique. - 3. 1 Lens- and Mirror-Type Systems. - 3. 2 Sensitivity. - 3. 3 Measuring Range. - 3. 4 Estimating the Sensitivity and Range Required. - 3. 5 Resolving Power. - 3. 6 Diffraction Effects. - 3. 7 Magnification and Depth of Field. - 4 Large-Field and Focusing Schlieren Methods. - 4. 1 Large Single- and Double-Mirror Systems. - 4. 2 Traditional Schlieren Systems with Large Light Sources. - 4. 3 Lens-and-Grid Techniques. - 4. 4 Large-Field Scanning Schlieren Systems. - 4. 5 Moiré-Fringe Methods. - 4. 6 Holographic and Tomographic Schlieren. - 5 Specialized Schlieren Techniques. - 5. 1 Special Schlieren CutoffsIll. - 5. 1. 1 Graded Filters. - 5. 2 Color Schlieren Methods. - 5. 3 Stereoscopic Schlieren. - 5. 4 Schlieren Interferometry. - 5. 5 Computer-Simulated Schlieren. - 5. 6 Various Specialized Techniques. - 6 Shadowgraph Techniques. - 6. 1 Background. - 6. 2 Direct Shadowgraphy. - 6. 3 Focused Shadowgraphy. - 6. 4 Specialized Shadowgraph Techniques. - 7 Practical Issues. - 7. 1 Optical Components. - 7. 2 Equipment Fabrication, Alignment, and Operation. - 7. 3 Capturing Schlieren Images and Shadowgrams. - 7. 4 Commercial and Portable Schlieren Instruments. - 8 Setting Up Your Own Simple Schlieren and Shadowgraph System. - 8. 1 Designing the Schlieren System. - 8. 2 Determining the Cost. - 8. 3 Choosing a Setup Location. - 8. 4 Aligning the Optics. - 8. 5 Troubleshooting. - 8. 6 Recording the Schlieren Image or Shadowgram. -8. 7 Conclusion. - 9 Applications. - 9. 1 Phenomena in Solids. - 9. 2 Phenomena in Liquids. - 9. 3 Phenomena in Gases. - 9. 4 Other Applications. - 10 Quantitative Evaluation. - 10. 1 Quantitative Schlieren Evaluation by Photometry. - 10. 2 Grid-Cutoff Methods. - 10. 3 Quantitative Image Velocimetry. - 10. 4 Quantitative Shadowgraphy. - 11 Summary and Outlook. - 11. 1 Summary. - 11. 2 Outlook: Issues for the Future. - 11. 3 Closing Remarks. - References. - Appendix A Optical Fundamentals. - A. 1 Radiometry and Photometry. - A. 2 Refraction Angle 8. - A. 2. 1 Small Optical Angles and Paraxial Space. - A. 2. 2 Huygens' Principle and Refraction. - A. 3 Optical Components and Devices. - A. 3. 1 Conjugate Optical Planes. - A. 3. 2 Lensf/number. - A. 3. 3 The Thin-Lens Approximation. - A. 3. 4 Viewing Screens and Ground Glass. - A. 3. 5 Optical Density. - A. 4 Optical Aberrations. - A. 5 Light and the Human Eye. - A. 6 Geometric Theory of Light Refraction by a Schliere. - Appendix B The Schlieren System as a Fourier Optical Processor. - B. 1 The Basic Fourier Processor with no Schlieren Present. - B. 2 The Addition of a Schlieren Test Object. - B. 3 The Schlieren Cutoff. - B. 4 Other Spatial Filters. - B. 5 Partially-Coherent and Polychromatic Illumination. - Appendix C Parts List for a Simple Schlieren/ Shadowgraph System. - C. l Optics. - C. 2 Illumination. - C. 3 Miscellaneous Components. - C. 4 Optical Mounts. - Appendix D Suppliers of Schlieren Systems and Components. - D. l Complete Schlieren Systems. - D. 2 Schlieren Field Mirrors. - D. 3 Light Sources. - D. 4 Components. - D. 5 Focusing Schlieren Lenses. - D. 6 Miscellaneous. - Color Plates.