Gustavo Rodríguez, Jesús Villa, Rumen Ivanov, Efrén González, and Geminiano Martínez J. Opt. Soc. Am. A 33(8) 1604-1611 (2016)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution. Contact your librarian or system administrator or Login to access Optica Member Subscription

Foucaulttestanalysis

These distortions lead to a larger beam waist compared to Gaussian beams when the same focal lens is used. This results in a lower maximum achievable power density in the focal point.

where Θ0 and D0 are the divergence and waist of a higher mode beam and M2 is greater than 1 and is named the “Beam Propagation Ratio” per the ISO 11146 standard. When a Gaussian laser beam is focused, the focused spot diameter is defined by

Foucaulttest

The beam quality of a laser is an important aspect of laser characterization. It can be defined in different ways, but is normally understood as a measure of how tightly a laser beam can be focused under certain conditions. The most common ways to quantify the beam quality are:

Ronchitestsetup

where d00 is the ideal focused spot diameter, f is the focal length of the focusing lens, and D00 is the input beam waist and is placed one focal length from the lens as shown in the figure. However, when a multimode beam is focused, Equation becomes

This website uses cookies to deliver some of our products and services as well as for analytics and to provide you a more personalized experience. Click here to learn more. By continuing to use this site, you agree to our use of cookies. We've also updated our Privacy Notice. Click here to see what's new.

In the focus (beam waist) of a diffraction-limited beam (i.e., at the location where the beam radius reaches its minimum), the optical wavefronts are flat. Any scrambling of the wavefronts, e.g. due to optical components with poor quality, spherical aberrations of lenses, thermal effects in a gain medium, diffraction at apertures, or by parasitic reflections, can spoil the beam quality. For monochromatic beams, the beam quality could in principle be restored e.g. with a phase mask which exactly compensates the wavefront distortions, but this is usually difficult in practice, even in cases where the distortions are stationary. A more flexible approach is to use adaptive optics in combination with a wavefront sensor.

The work described in the foregoing paper made the development of a quantitative method of surveying surfaces necessary, that could be used for local measurements and on nonsymmetric surfaces. The theory of the method and the experimental technique are described. The accuracy of the survey is better than 1/20 wave-length with visual subjective observation and could be carried up to 1/100 wave-length with objective photographic measurements. The errors of the Foucault knife-edge test, especially the one produced by parallax, are discussed. Ways of reducing or eliminating them are described.

Ronchitest

This website uses cookies to deliver some of our products and services as well as for analytics and to provide you a more personalized experience. Click here to learn more. By continuing to use this site, you agree to our use of cookies. We've also updated our Privacy Notice. Click here to see what's new.

The work described in the foregoing paper made the development of a quantitative method of surveying surfaces necessary, that could be used for local measurements and on nonsymmetric surfaces. The theory of the method and the experimental technique are described. The accuracy of the survey is better than 1/20 wave-length with visual subjective observation and could be carried up to 1/100 wave-length with objective photographic measurements. The errors of the Foucault knife-edge test, especially the one produced by parallax, are discussed. Ways of reducing or eliminating them are described.

Knife edgelens thickness

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution. Contact your librarian or system administrator or Login to access Optica Member Subscription

What is laser beam quality factor? How to evaluate laser beam quality? Why laser beam quality degrades during propagation? This article will share a bit it.

Foucaultknife edge test

With a given divergence angle (i.e. knowing the focal length of the lens), the fundamental mode alone produces the theoretically smallest possible beam waist (green curve). If beam quality worsens (red curve), the beam waist increases. If divergence is fixed, beam waist increases linearly by the factor M2 compared to the underlying Gaussian.

Using a Gaussian beam is preferred because of its minimum divergence angle and the ability to achieve the minimal focus diameter. Differences to Gaussian shape can be due to

where D00 is the diameter of the beam waist, and λ is the wavelength. Higher mode beams often start with a larger beam waist, D0, and/or have a faster divergence Θ0. In this case Equation becomes

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution. Contact your librarian or system administrator or Login to access Optica Member Subscription