Optical Measurement Mechanics

Kaifu Wang

• Éditeur: De Gruyter
• Année: 2018
• ISBN:
  9783110573206
• Édition: 1
• Sujet: Naturwissenschaften
• Sous-sujet: Optik & Licht

The book introduces the fundamentals of optical measurement mechanics, and discusses different types of interferometry, including (Digital) Holographic Interferometry, (Digital) Speckle Interferometry, Moiré Interferometry, Digital Image Correlation and Particle Image Velocimetry. It is an essential reference for graduate students, scientists and practitioners from both universities and research laboratories.

1Optical measurement mechanics fundamentals

Optical measurement mechanics (or photomechanics) is an experimental interdiscipline related to optics and mechanics. Optical measurement mechanics can be used for solving mechanical problems, such as deformation measurement, vibration analysis, nondestructive testing, etc., by employing optical techniques, such as holographic interferometry, speckle interferometry, moiré interferometry, etc.

1.1Optics

Optics is the branch of physics that is concerned with light and vision and deals chiefly with the generation, propagation, and detection of electromagnetic radiation having wavelengths greater than X-rays and shorter than microwaves.

Optics usually describes the behavior and property of light. Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum and usually refers to visible light, which is visible to the human eye and is responsible for the sense of sight. Visible light has wavelengths in the range from about 400 (violet) to 760 (red) nanometers between infrared (with longer wavelengths) and ultraviolet (with shorter wavelengths).

Often, infrared and ultraviolet are also called light. Infrared light has the range of invisible radiation wavelengths froma bout 760 nm, just greater than red in the visible spectrum, to 1 mm, on the border of the microwave region. Ultraviolet light has the range of invisible radiation wavelengths from about 4 nm, on the border of the X-ray region, to about 400 nm, just beyond the violet in the visible spectrum.

1.1.1Geometrical optics

Most optical phenomena can be accounted for using the classical electromagnetic description of light. However, a complete electromagnetic description of light is often difficult to apply in practice. Therefore, simplified models are usually utilized in optics. One of the commonly used models is called geometrical optics, or ray optics. Geometrical optics treats light as a collection of light rays and describes light propagation in terms of light rays. A light ray is a straight or curved line that is perpendicular to the wavefront of light and is therefore collinear with the wave vector. A slightly more rigorous definition of light ray follows from Fermat’s principle, which states that the path taken between two points by a ray of light is the path that can be traversed in the least time. The light ray in geometrical optics is useful in approximating the paths along which light propagates in certain classes of media.

The simplifying assumptions in geometrical optics are mainly that light rays: (1) propagate in rectilinear paths as they travel in ...