Book contents
- Introduction to Lens Design
- Introduction to Lens Design
- Copyright page
- Dedication
- Epigraph
- Contents
- Preface
- 1 Introduction
- 2 Classical Imaging, First-Order Imaging, and Imaging Aberrations
- 3 Aspheric Surfaces
- 4 Thin Lenses
- 5 Ray Tracing
- 6 Radiometry in a Lens System
- 7 Achromatic and Athermal Lenses
- 8 Combinations of Achromatic Doublets
- 9 Image Evaluation
- 10 Lens Tolerancing
- 11 Using Lens Design Software
- 12 Petzval Portrait Objective, Cooke Triplet, and Double Gauss Lens
- 13 Lens System Combinations
- 14 Ghost Image Analysis
- 15 Designing with Off-the-Shelf Lenses
- 16 Mirror Systems
- 17 Miniature Lenses
- 18 Zoom Lenses
- Book part
- Glossary
- Further Reading on Lens Design
- Index
- References
7 - Achromatic and Athermal Lenses
Published online by Cambridge University Press: 23 September 2019
- Introduction to Lens Design
- Introduction to Lens Design
- Copyright page
- Dedication
- Epigraph
- Contents
- Preface
- 1 Introduction
- 2 Classical Imaging, First-Order Imaging, and Imaging Aberrations
- 3 Aspheric Surfaces
- 4 Thin Lenses
- 5 Ray Tracing
- 6 Radiometry in a Lens System
- 7 Achromatic and Athermal Lenses
- 8 Combinations of Achromatic Doublets
- 9 Image Evaluation
- 10 Lens Tolerancing
- 11 Using Lens Design Software
- 12 Petzval Portrait Objective, Cooke Triplet, and Double Gauss Lens
- 13 Lens System Combinations
- 14 Ghost Image Analysis
- 15 Designing with Off-the-Shelf Lenses
- 16 Mirror Systems
- 17 Miniature Lenses
- 18 Zoom Lenses
- Book part
- Glossary
- Further Reading on Lens Design
- Index
- References
Summary
The index of refraction of glass depends on the wavelength of light. For N-BK7 glass from Schott Company, the index of refraction is shown in Figure 7.1 for wavelengths ranging from 0.4 to 0.8 µm; shorter wavelengths have a higher index of refraction than longer wavelengths. Since the angle of refraction depends on the index of refraction, then the angle of refraction varies as the wavelength changes. This results in chromatic aberration. Similarly, the index of refraction and the radii of curvature and thickness of a lens vary with changes in lens temperature. This results in thermal aberrations; thermal change of focus, and thermal change of magnification. This chapter discusses both types of aberrations and their correction.
- Type
- Chapter
- Information
- Introduction to Lens Design , pp. 64 - 80Publisher: Cambridge University PressPrint publication year: 2019