A simple technique for measuring the M2 parameter and the optical focus of the light exiting the objective lens in a laser scanning microscope

Johanna Trägårdh, Greg Norris, Stuart Wilson, Christopher Travis, Gian-Luca Oppo, Gail McConnell

Research output: Contribution to conferencePoster

Abstract

We report a method for measuring the optical quality of the post-objective laser radiation in a laser scanning microscope. We use a microscopic-scale knife-edge in the form of a simple transmission electron microscopy grid attached to a glass microscope slide and a light-collecting optical fibre and photodiode underneath the specimen. By scanning the laser spot from a reflective to a transmitting part of the grid, an error function measuring the beam can be obtained and by repeating this with the knife-edge at different axial positions relative to the beam waist, the M2 parameter of the post-objective laser beam can be obtained, together with measurements of the size of the optical focus, the ellipticity and the astigmatism of the laser beam exiting the objective lens. This measurement is useful not only for measuring the size of the optical focus, but also for evaluating the beam divergence and thus evaluating how much of the full numerical aperture of the lens is used in practice, which impacts the imaging quality in confocal and multi-photon microscopy.
We will present details of the measurement technique, as well as data of beam divergence, ellipticity, astigmatism and M2 parameters obtained with very high (1.3) and low (0.15, 0.7) numerical aperture lenses and lasers commonly used in confocal and multi-photon laser scanning microscopy

Conference

ConferencePhoton14
CountryUnited Kingdom
CityLondon
Period1/09/144/09/14
Internet address

Fingerprint

Lenses
Lasers
microscopes
lenses
Light
scanning
lasers
Astigmatism
astigmatism
laser beams
ellipticity
numerical aperture
Photons
divergence
grids
microscopy
Optical Fibers
error functions
photons
Transmission Electron Microscopy

Keywords

  • optical focus
  • laser scanning microscope
  • measuring technique

Cite this

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title = "A simple technique for measuring the M2 parameter and the optical focus of the light exiting the objective lens in a laser scanning microscope",
abstract = "We report a method for measuring the optical quality of the post-objective laser radiation in a laser scanning microscope. We use a microscopic-scale knife-edge in the form of a simple transmission electron microscopy grid attached to a glass microscope slide and a light-collecting optical fibre and photodiode underneath the specimen. By scanning the laser spot from a reflective to a transmitting part of the grid, an error function measuring the beam can be obtained and by repeating this with the knife-edge at different axial positions relative to the beam waist, the M2 parameter of the post-objective laser beam can be obtained, together with measurements of the size of the optical focus, the ellipticity and the astigmatism of the laser beam exiting the objective lens. This measurement is useful not only for measuring the size of the optical focus, but also for evaluating the beam divergence and thus evaluating how much of the full numerical aperture of the lens is used in practice, which impacts the imaging quality in confocal and multi-photon microscopy.We will present details of the measurement technique, as well as data of beam divergence, ellipticity, astigmatism and M2 parameters obtained with very high (1.3) and low (0.15, 0.7) numerical aperture lenses and lasers commonly used in confocal and multi-photon laser scanning microscopy",
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author = "Johanna Tr{\"a}g{\aa}rdh and Greg Norris and Stuart Wilson and Christopher Travis and Gian-Luca Oppo and Gail McConnell",
year = "2014",
month = "9",
day = "1",
language = "English",
note = "Photon14 ; Conference date: 01-09-2014 Through 04-09-2014",
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A simple technique for measuring the M2 parameter and the optical focus of the light exiting the objective lens in a laser scanning microscope. / Trägårdh, Johanna; Norris, Greg; Wilson, Stuart; Travis, Christopher; Oppo, Gian-Luca; McConnell, Gail.

2014. Poster session presented at Photon14, London, United Kingdom.

Research output: Contribution to conferencePoster

TY - CONF

T1 - A simple technique for measuring the M2 parameter and the optical focus of the light exiting the objective lens in a laser scanning microscope

AU - Trägårdh, Johanna

AU - Norris, Greg

AU - Wilson, Stuart

AU - Travis, Christopher

AU - Oppo, Gian-Luca

AU - McConnell, Gail

PY - 2014/9/1

Y1 - 2014/9/1

N2 - We report a method for measuring the optical quality of the post-objective laser radiation in a laser scanning microscope. We use a microscopic-scale knife-edge in the form of a simple transmission electron microscopy grid attached to a glass microscope slide and a light-collecting optical fibre and photodiode underneath the specimen. By scanning the laser spot from a reflective to a transmitting part of the grid, an error function measuring the beam can be obtained and by repeating this with the knife-edge at different axial positions relative to the beam waist, the M2 parameter of the post-objective laser beam can be obtained, together with measurements of the size of the optical focus, the ellipticity and the astigmatism of the laser beam exiting the objective lens. This measurement is useful not only for measuring the size of the optical focus, but also for evaluating the beam divergence and thus evaluating how much of the full numerical aperture of the lens is used in practice, which impacts the imaging quality in confocal and multi-photon microscopy.We will present details of the measurement technique, as well as data of beam divergence, ellipticity, astigmatism and M2 parameters obtained with very high (1.3) and low (0.15, 0.7) numerical aperture lenses and lasers commonly used in confocal and multi-photon laser scanning microscopy

AB - We report a method for measuring the optical quality of the post-objective laser radiation in a laser scanning microscope. We use a microscopic-scale knife-edge in the form of a simple transmission electron microscopy grid attached to a glass microscope slide and a light-collecting optical fibre and photodiode underneath the specimen. By scanning the laser spot from a reflective to a transmitting part of the grid, an error function measuring the beam can be obtained and by repeating this with the knife-edge at different axial positions relative to the beam waist, the M2 parameter of the post-objective laser beam can be obtained, together with measurements of the size of the optical focus, the ellipticity and the astigmatism of the laser beam exiting the objective lens. This measurement is useful not only for measuring the size of the optical focus, but also for evaluating the beam divergence and thus evaluating how much of the full numerical aperture of the lens is used in practice, which impacts the imaging quality in confocal and multi-photon microscopy.We will present details of the measurement technique, as well as data of beam divergence, ellipticity, astigmatism and M2 parameters obtained with very high (1.3) and low (0.15, 0.7) numerical aperture lenses and lasers commonly used in confocal and multi-photon laser scanning microscopy

KW - optical focus

KW - laser scanning microscope

KW - measuring technique

UR - http://photon14.iopconfs.org/281952

M3 - Poster

ER -