US 5,583,342 AGranted

Laser scanning optical system and laser scanning optical apparatus

AssigneeHamamatsu Photonics K.K.

InventorKoji Ichie

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Abstract

A laser scanning optical system is so arranged to comprise an optical converting unit, an optical scanning unit, and an optical converging unit. Here, the optical converting unit is composed of two axicon prisms which are arranged such that apexes thereof are opposed forward or backward to each other at a predetermined distance and optical axes thereof are coincident with each other and which are made of respective materials having a same refractive index and shaped with a same apical angle. By this, the laser beam incident into the optical converting unit becomes a cylindrical ray bundle having an annular cross-sectional intensity perpendicular to the optical axis. Therefore, the cylindrical ray bundle is changed in the traveling direction by the optical scanning unit to be scanned and is then converged by the optical converging unit to become a Bessel beam having a high energy utilization factor, a high resolution and a long focal depth.

Claims4

Dependent claims

A method for obtaining a high resolution three-dimensional microscopic image of a sample having a three-dimensional thickness, comprising the steps of:

emitting a parallel rays pulsed laser beam, said laser beam having a pulse duration of several ten to several hundred fs and a repetitive frequency of several ten to several hundred MH.sub.z ;
shaping said laser beam into a cylindrical and annular cross-sectional ray bundle, by
providing first and second convex axicon prisms which are disposed such that apexes thereof are opposed one to the other and said apexes are separated by a distance one from the other and optical axes thereof are coincident with each other and which are made of respective materials having substantially the same refractive index and shaped with a same apical angle;
causing said laser beam to enter said first prism and then, after passing through said first prism, to enter said second prism;
and
adjusting a diameter of said ray bundle by adjusting said beam diameter either before said beam enters said first axicon prism or after said beam exits said second axicon prism;
converging said shaped laser beam to produce a Bessel beam;
changing a shape of three-dimensional intensity distribution of said Bessel beam by setting a ratio .beta. of an outer diameter .alpha. of said ray bundle to an inner diameter .alpha..sup.1 (namely .beta.=.alpha./.alpha..sup.1) by adjusting said distance;
irradiating said sample with said Bessel beam;
detecting fluorescence light emitted by said sample responsive to irradiation by said Bessel beam;
generating output signals corresponding to said detected light;
and
producing said microscopic image based on said output signals
wherein said detecting step comprises the steps of:
a) first detecting said fluorescence emitted from a surface side of said sample, and
b) second detecting said fluorescence emitted from a back side of said sample;
and
wherein producing said microscopic image based on addition of output signals corresponding to said detected fluorescence.

15 more elements

A method for obtaining a high resolution three-dimensional microscopic image of a sample having a three-dimensional thickness, comprising the steps of:

emitting a parallel rays pulsed laser beam, said laser beam having a pulse duration of several ten to several hundred fs and a repetitive frequency of several ten to several hundred MH.sub.z ;
shaping said laser beam into a cylindrical and annular cross-sectional ray bundle, by
providing first and second convex axicon prisms which are disposed such that apexes thereof are opposed one to the other and said apexes are separated by a distance one from the other and optical axes thereof are coincident with each other and which are made of respective materials having substantially the same refractive index and shaped with a same apical angle;
causing said laser beam to enter said first prism and then, after passing through said first prism, to enter said second prism;
and
adjusting a diameter of said ray bundle by adjusting said beam diameter either before said beam enters said first axicon prism or after said beam exits said second axicon prism;
converging said shaped laser beam to produce a Bessel beam;
changing a shape of three-dimensional intensity distribution of said Bessel beam by setting a ratio .beta. of an outer diameter .alpha. of said ray bundle to an inner diameter .alpha..sup.1 (namely .beta.=.alpha./.alpha..sup.1) by adjusting said distance;
labeling said sample with a predetermined fluorescent dye;
irradiating said sample with said Bessel beam;
detecting fluorescence light emitted by said sample responsive to irradiation by said Bessel beam;
generating output signals corresponding to said detected light;
and
producing said microscopic image based on said output signals
wherein said detecting step comprises:
a) first detecting said fluorescence emitted from a surface side of said sample, and
b) second detecting said fluorescence emitted from a back side of said sample;
and
wherein producing said microscopic image based on addition of output signals corresponding to said detected fluorescence.

16 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/525,419Filed 7 Sep 1995 · continuation
Priority: JP 5-1336593 Jun 1993
Granted: 10 Dec 1996
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G02B 27/09
Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00: beam shaping, e.g. changing the…
G02B 5/001
Optical elements other than lenses: axicons, waxicons, reflaxicons
G02B 21/0032
Confocal scanning microscopes or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders: optical…
G02B 21/0072
Optical details of the image generation: details concerning resolution or correction, including general design of CSOM objectives