Device and method for illuminating a sample

Patent metadata

Field	Value
Publication number	US-2016290928-A1
Application number	US-201415037451-A
Country	US
Kind code	A1
Filing date	Nov 19, 2014
Priority date	Nov 19, 2013
Publication date	Oct 6, 2016
Grant date	—

Abstract

A device ( 10 ) for illuminating a sample ( 40 ) is described, having: at least one pulsed laser light source ( 12 ) for repeated emission of a first laser pulse along a first light path ( 14 ) and of a second laser pulse along a second light path ( 16 ) physically separated from the first light path; a superimposition element ( 32 ) for collinear superimposition of the two laser pulses in a shared light path ( 34 ); a delay stage ( 26 ) arranged in the first or the second light path ( 14, 16 ), for delaying one of the two laser pulses relative to the other laser pulse in such a way that the two laser pulses sent along the shared light path ( 34 ) onto the sample ( 40 ) exhibit a temporal superimposition; a shared chirp unit ( 36 ) arranged in the shared light path ( 34 ), for frequency-modifying influencing both of the first laser pulse and of the second laser pulse; and at least one separate chirp unit ( 18 ) arranged in the first light path ( 14 ), for frequency-modifying influencing only of the first laser pulse. The shared chirp unit ( 36 ) and the separate chirp unit ( 18 ) are coordinated with one another in order to achieve a target state. The separate chirp unit ( 18 ) is coupled to a control system ( 20 ) by which the separate chirp unit ( 18 ) is controllable with a control parameter dependent on the wavelength of the first laser pulse in order to establish the target state.

First claim

What is claimed is:

1 . A device for illuminating a sample, having
at least one pulsed laser light source for repeated emission of a first laser pulse along a first light path and of a second laser pulse along a second light path physically separated from the first light path; a superimposition element for collinear superimposition of the two laser pulses in a shared light path; a delay stage, arranged in the first or the second light path, for delaying one of the two laser pulses relative to the other laser pulse in such a way that the two laser pulses sent along the shared light path onto the sample exhibit a temporal superimposition; a shared chirp unit, arranged in the shared light path, for frequency-modifying influencing both of the first laser pulse and of the second laser pulse; and at least one separate chirp unit, arranged in the first light path, for frequency-modifying influencing only of the first laser pulse, the shared chirp unit and the separate chirp unit being coordinated with one another in order to achieve a target state in which an instantaneous frequency of the first laser pulse influenced both by the separate chirp unit and by the shared chirp unit, and an instantaneous frequency of the second laser pulse influenced only by the shared chirp unit, have a predetermined relationship to one another, wherein at least the wavelength of the first light pulse is variable in a predetermined wavelength range by means of the pulsed laser light source; and the separate chirp unit is coupled to a control system by which the separate chirp unit is controllable with a control parameter dependent on the wavelength of the first laser pulse in order to establish the target state.

2 . The device according to claim 1 , wherein in the target state the difference between the instantaneous frequency of the first laser pulse influenced both by the separate chirp unit and by the shared chirp unit, and the instantaneous frequency of the second laser pulse influenced only by the shared chirp unit, is constant during the temporal superimposition of the two laser pulses.

3 . The device according to claim 1 , wherein the shared chirp unit is constituted by an optical modulator or an optical filter.

4 . The device according to claim 1 , characterized by an additional separate chirp unit that is controllable for frequency-modifying influencing only of the second laser pulse in the second light path.

5 . The device according to claim 1 , wherein the at least one separate, controllable chirp unit is contained in the pulsed laser light source.

6 . The device according to claim 1 , wherein the at least one separate, controllable chirp unit is arranged outside the pulsed laser light source.

7 . The device according to claim 1 , characterized by two pulsed laser light sources, of which a first is associated with the first light path and a second with the second light path.

8 . The device according to claim 1 , wherein one of the two pulsed laser light sources is constituted by an optical parametric oscillator or amplifier that is coupled via a beam splitter to a laser output of the other pulsed laser light source.

9 . The device according to claim 1 , wherein the separate chirp unit is controllable, in order to establish the target state, in such a way that the pulse width of the first laser pulse at the sample is greater than a smallest possible pulse width settable by means of the separate chirp unit.

10 . A method for illuminating a sample, in which method
by means of at least one pulsed laser light source, a first laser pulse is repeatedly emitted along a first light path and a second laser pulse is repeatedly emitted along a second light path physically separated from the first light path; the two laser pulses are collinearly superimposed in a shared light path; one of the two laser pulses is delayed relative to the other laser pulse in such a way that the two laser pulses sent along the shared light path onto the sample exhibit a temporal superimposition; by means of a shared chirp unit arranged in the shared light path, both the first laser pulse and the second laser pulse are influenced in frequency-modifying fashion; and by means of at least one separate chirp unit arranged in the first light path, only the first laser pulse is influenced in frequency-modifying fashion, the separate chirp unit and the shared chirp unit being coordinated with one another in order to achieve a target state in which an instantaneous frequency of the first laser pulse influenced both by the separate chirp unit and by the shared chirp unit, and an instantaneous frequency of the second laser pulse influenced only by the shared chirp unit, have a predetermined relationship to one another, wherein at least the wavelength of the first light pulse is varied in a predetermined wavelength range by means of the pulsed laser light source; and the separate chirp unit is controlled by means of a control system with a control parameter dependent on the wavelength of the first laser pulse in order to establish the target state.

11 . The method according to claim 10 , wherein the first laser pulse and the second laser pulse are respectively approximated by a Gaussian pulse whose normalized electric field E(z,T) is described by the following equation:

E


(

z
,
T

)

=

exp


(

-

(

1
+
iC

)



T
2

2


T
o
2

)



exp

-

i


(

kz
-

ω



T

)

,

in which
z d

Assignees

• Leica Microsystems

Inventors

• Krishnamachari Vishnu Vardhan
• Seyfried Volker
• Hay William C
• Kremer Manuel

Classifications

• G02B21/0076

  arrangements using fluorescence or luminescence · CPC title

• G02B21/16

  adapted for ultraviolet illumination {; Fluorescence microscopes (G02B21/0076 takes precedence)} · CPC title

• G01N21/65 Primary

  Raman scattering · CPC title

• G01N2201/06113

  Coherent sources; lasers · CPC title

• G02B21/0032

  Optical details of illumination, e.g. light-sources, pinholes, beam splitters, slits, fibers (G02B21/0036 - G02B21/008; means for illumination of specimens in general G02B21/06) · CPC title