Autofocus imaging for a microscope

1. Autofocus imaging system for a microscope, the autofocus imaging system comprising:

a primary image sensor arrangement comprising a primary image sensor ( 24 ) for acquiring primary image data of an object of interest ( 4 );

an autofocus image sensor ( 26 ) for acquiring autofocus image data of an oblique section of the object of interest ( 4 );

wherein the primary image sensor ( 24 ) is configured for sampling a first number of pixels per distance in object space;

wherein the autofocus image sensor ( 26 ) is configured for sampling a second number of pixels per distance in object space;

wherein the second number is between one quarter and three quarters of the first number.

2. The autofocus imaging system of claim 1 ,

wherein the second number is half of the first number.

3. The autofocus imaging system of claim 1 ,

wherein a resolution of the primary image sensor is wavelength (λ)/(2*numerical aperture (NA)); and

wherein a resolution of the autofocus image sensor is λ/(NA).

4. The autofocus imaging system of claim 1 ,

wherein the autofocus image sensor ( 26 ) is tilted with respect to an optical axis ( 31 ) of the primary image sensor ( 24 ).

5. The autofocus imaging system of claim 1 ,

wherein the autofocus image sensor ( 26 ) is tilted in a scan direction ( 6 ) of the autofocus imaging system.

6. The autofocus imaging system of claim 1 , further comprising:

a beam splitter ( 22 ) for splitting a beam from the object into a first beam towards the primary image sensor and a second beam towards the autofocus image sensor;

wherein the a fraction between an intensity of the second beam and an intensity of the first beam is bigger than (1−L 0 /L max ), wherein L 0 is a number of stages needed to focus with no autofocus sensor and L max is a maximum number of Time Delay Integration stages of the primary image sensor.

7. The autofocus imaging system of claim 1 ,

wherein the autofocus image sensor ( 24 ) is configured for acquiring the autofocus image data at a light frequency outside the frequency of the visible spectrum.

8. The autofocus imaging system of claim 1 ,

wherein the autofocus imaging system ( 500 ) is configured for dark field illumination of the autofocus image sensor.

9. The autofocus imaging system of claim 1 ,

wherein the primary image sensor arrangement further comprises a second primary image sensor ( 32 ) and a third primary image sensor ( 33 );

wherein each of the primary image sensors of the primary image sensor arrangement is configured for detecting light of a different wavelength.

10. The autofocus imaging system of claim 1 ,

wherein the primary image sensor ( 24 ) is a line sensor, and

wherein the autofocus image sensor ( 24 ) is a two-dimensional sensor.

11. The autofocus imaging system of claim 1 , wherein the primary image sensor and the autofocus image sensor share a same sensing area.

12. A microscope ( 802 ) comprising an autofocus imaging system ( 500 ) of claim 1 .

13. A method for autofocus imaging of a microscope ( 802 ), the method comprising the following steps:

acquiring primary image data of an object of interest by a primary image sensor ( 24 ) of a primary image sensor arrangement;

acquiring autofocus image data of an oblique section of the object of interest by an autofocus image sensor ( 26 );

sampling a first number of pixels per distance in object space, the first number of pixels being pixels of the primary image sensor ( 24 );

sampling a second number of pixels per distance in object space, the second number of pixels being pixels of the autofocus image sensor ( 26 );

wherein the second number is between one quarter and three quarters of the first number.

14. A non-volatile computer-readable storage medium, in which a computer program for autofocus imaging of a microscope is stored which, when executed by a processor ( 800 ) of the microscope ( 802 ), causes the processor ( 800 ) to carry out the steps of:

acquiring primary image data of an object of interest from a primary image sensor ( 24 ) of a primary image sensor arrangement;

acquiring autofocus image data of an oblique section of the object of interest from an autofocus image sensor ( 26 );

sampling a first number of pixels per distance in object space, the first number of pixels being pixels of the primary image sensor ( 24 );

sampling a second number of pixels per distance in object space, the second number of pixels being pixels of the autofocus image sensor ( 26 );

wherein the second number is between one quarter and three quarters of the first number.

15. A non-volatile computer readable program medium having encoded thereon a program element for autofocus imaging of a microscope, which, when being executed by a processor ( 800 ) of the microscope ( 802 ), causes the processor to carry out the steps of:

acquiring primary image data of an object of interest from a primary image sensor ( 24 ) of a primary image sensor arrangement;

acquiring autofocus image data of an oblique section of the object of interest from an autofocus image sensor ( 26 );

sampling a first number of pixels per distance in object space, the first number of pixels being pixels of the primary image sensor ( 24 );

sampling a second number of pixels per distance in object space, the second number of pixels being pixels of the autofocus image sensor ( 26 );

wherein the second number is between one quarter and three quarters of the first number.