Method of and apparatus for imaging light emitting objects on an image sensor

Patent metadata

Field	Value
Publication number	US-12050326-B2
Application number	US-202117393690-A
Country	US
Kind code	B2
Filing date	Aug 4, 2021
Priority date	Feb 4, 2019
Publication date	Jul 30, 2024
Grant date	Jul 30, 2024

Abstract

An optical module for imaging light emitting objects on an image sensor comprises a polarizing beam splitter having an entrance face, an exit face, first and a second return faces, a first reflector facing the first return face, a first achromatic quarter-wave retardation plate between the first return face and the first reflector, a second reflector facing the second return face, and a second achromatic quarter-wave retardation plate between the second return face and the second reflector. The first and second reflectors differ in at least one of their orientation with regard to the first and second return faces or their spectral properties. At least one of the first reflector and the second reflector comprises a dichroic mirror arranged between the respective achromatic quarter-wave retardation plate and a further mirror of the respective reflector. The dichroic mirror is tilted with regard to the further mirror of the respective reflector.

First claim

We claim:

1. An optical module for imaging light emitting objects on an image sensor, the optical module comprising:
a polarizing beam splitter (PBS) having an entrance face, an exit face, a first return face and a second return face,
a first reflector facing the first return face,
a first achromatic quarter-wave retardation plate arranged between the first return face and the first reflector,
a second reflector facing the second return face, and
a second achromatic quarter-wave retardation plate arranged between the second return face and the second reflector,
wherein the first reflector and the second reflector differ in at least one of their orientation with regard to the first and second return faces or their spectral properties, wherein at least one of the first reflector and the second reflector comprises at least one of
at least one dichroic mirror arranged between the respective first or second achromatic quarter-wave retardation plate and a further mirror of the at least one of the first reflector and the second reflector, wherein the at least one dichroic mirror is tilted with regard to the further mirror of the at least one of the first reflector and the second reflector,
a dispersive prism,
a diffractive grating,
an electro optical deflector, and
a phase mask.

2. The optical module of claim 1 , wherein the first reflector has a first plane mirror surface and the second reflector has a second plane mirror surface, wherein the first plane mirror surface is oriented at an offset angle to a plane conjugated to the second plane mirror surface, wherein the offset angle is in a range from 2/MD to 5/MD, wherein is a design wavelength of the optical module and MD is a minimum diameter of the entrance and exit faces.

3. The optical module of claim 1 , wherein the first reflector comprises a first dichroic mirror of a first cutoff wavelength and the second reflector comprises a second dichroic mirror of a second cutoff wavelength different to the first cutoff wavelength of the first dichroic mirrors.

4. The optical module of claim 1 , wherein the at least one of the dispersive prism and the diffractive grating is a Littrow prism or a Littrow grating.

5. The optical module of claim 1 , wherein a birefringent optical unit comprising at least one of an achromatic quarter-wave retardation plate and a Wollaston prism is arranged in front of the entrance face.

6. The optical module of claim 1 , wherein the polarizing beam splitter is a PBS cube or a Foster PBS.

7. The optical module of claim 1 , wherein the optical module is a monolithic unit in which all optical elements are fixed to each other.

8. The optical module of claim 7 , wherein at least one transparent optical wedge is arranged between one mirror of one of the first reflector and the second reflector and the respective first or second return face of the PBS.

9. A parallelized confocal, RESOLFT or STED scanning light microscope comprising
a light source,
an objective,
a sample holder,
an image sensor,
an excitation light beam path extending from the light source, through the objective and towards the sample holder, and configured to form a plurality of separate effective excitation volumes in a sample held by the sample holder,
a detection light beam path extending from the sample, through the objective and up to an image sensor, and configured to image light emitted by the sample out of the separate effective excitation volumes into separate areas of the image sensor, and
the optical module of claim 1 arranged in the detection beam path.

10. A method of imaging light emitting objects on an image sensor of a widefield fluorescence light microscope, the method comprising,
arranging an optical module between a microscope objective and the image sensor of the widefield fluorescence light microscope, the optical module comprising:
a polarizing beam splitter (PBS) having an entrance face, an exit face, a first return face and a second return face,
a first reflector facing the first return face,
a first achromatic quarter-wave retardation plate arranged between the first return face and the first reflector,
a second reflector facing the second return face, and
a second achromatic quarter-wave retardation plate arranged between the second return face and the second reflector,
wherein the first reflector and the second reflector differ in at least one of their orientation with regard to the first and second return faces or their spectral properties, wherein at least one of the first reflector and the second reflector comprises at least one of
at least one dichroic mirror arranged between the respective first or second achromatic quarter-wave retardation plate and a further mirror of the at least one of the first reflector and the second reflector, wherein the at least one dichroic mirror is tilted with regard to the further mirror of the at least one of the first reflector and the second reflector,
a dispersive prism,
a diffractive grating,
an electro optical deflector, and

a phase mask,

using the optical module for splitting a first partial beam and a second partial beam off light coming from the objects,
using the optical module for simultaneously forming, on the same image sensor, at a same magnification, and in a same orientation, a first image and a second image of the objects of the first partial beam and of the second partial beam, respectively, and for arranging_the first image and the second image on the image sensor at a first lateral offset,
wherein the first image and the second image of the objects overlap by more than 50% of their areas on the image sensor, and
wherein the first lateral offset is at least 20% of a maximum full width at half maximum (FWHM) in direction of the first lateral offset of a first point spread function (PSF) in imaging any one particular point of the objects in the first image and of a second PSF in imaging the same one particular point of the objects in the second image.

11. The method of claim 10 , wherein the first lateral offset is in a range from a minimum percentage to a maximum percentage of the maximum FWHM in direction of the first lateral offset, wherein the minimum percentage is 200% and wherein the maximum percentage is 500%.

12. The method of claim 10 , further comprising
dividing-up at least one of the first partial beam and the second partial beam in a first sub-beam and a second sub-beam,
forming the respective first or second image of the objects of the at least one of the first partial beam and the second partial beam as a double image comprising a first part image formed of the first sub-beam and a second part image formed of the second sub-beam, and
arranging the first part image and the second part image at a second lateral offset in such a way that the maximum FWHMs of the PSFs of any one particular point of the objects in the first and second images and in the first and second part images will not overlap.

13. The method of claim 12 , wherein third and fourth components of the light of the at least one of the first and second partial beams divided-up in the first and second sub-beams differ in their wavelength ranges.

14. The method of claim 10 , wherein imaging any one particular point of the objects in the first image or the second image further comprises
expanding at least one PSF in a lateral direction in that the light of the first partial beam or the second partial beam, respectively, is deviated in the lateral direction depending on its wavelength, and
shifting at least one PSF with time in a lateral direction in that the light of the first partial beam or the second p

Assignees

• Max Planck Gesellschaft
• Katholieke Univ Leuven Ku Leuven Research & Development

Inventors

• Leutenegger Marcel
• Vandenberg Wim
• Dedecker Peter
• Bouwens Arno

Classifications

• G02B27/283

  used for beam splitting or combining · CPC title

• G02B26/0891

  forming an optical wedge · CPC title

• G02B21/365

  Control or image processing arrangements for digital or video microscopes (G02B21/361, G02B21/362 take precedence) · CPC title

• G02B21/16

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

• G02B21/0076 Primary

  arrangements using fluorescence or luminescence · CPC title