Multidirectional selective plane illumination microscopy

1. A selective plane illumination microscope comprising:

a) a laser unit producing a light beam;

b) a beam path switcher alternately directing the light beam along two distinct paths producing two alternating light beams;

c) two illumination units producing from the two alternating light beams two respective counter-propagating, coplanar, alternating light sheets; wherein the two alternating light sheets alternately illuminate the focal plane from opposite directions,

d) a detection unit focused on a focal plane for detecting images of a cross-section positioned in the focal plane while the cross-section is illumined by the alternating light sheets produced by the two illumination units; wherein the focal plane is coplanar with the alternating light sheets; wherein the detection unit has a detection axis perpendicular to an axis of propagation of the alternating light sheets;

e) an image processor for producing fused image data from the images of the cross-section positioned in the focal plane detected while the cross-section was illumined by the alternating light sheets produced by the two illumination units, wherein the fused image data represents an image of the cross-section having improved image quality.

2. The selective plane illumination microscope of claim 1 further comprising:

a scan unit with a resonant mirror producing from the light beam a light beam having an oscillating path, wherein the oscillating path causes a pivot through the focal plane of the alternating light sheets at angles determined by the resonant mirror.

3. The selective plane illumination microscope of claim 2 wherein the angles range over +/−10 degrees.

4. The selective plane illumination microscope of claim 2 wherein the frequency is on the order of 1 kHz.

5. The selective plane illumination microscope of claim 1 wherein the detection unit is synchronized with the beam path switcher.

6. The selective plane illumination microscope of claim 1 further comprising:

an additional detection unit focused on the focal plane.

7. The selective plane illumination microscope of claim 1 further comprising two additional illumination units; wherein:

the beam path switcher further alternately directs each of the two alternating light beams to produce four alternately directed light beams along four distinct paths;

the two additional illumination units, together with the two illumination units produce from the four alternating light beams four respective counter-propagating, coplanar, alternating light sheets.

8. The selective plane illumination microscope of claim 1 wherein at least one of the illumination units comprises adaptive optics, an optical detector, and a feedback system for adapting opposing light beams to improve imaging.

9. A method for selective plane illumination microscopy comprising:

a) alternately illuminating a focal plane with two counter-propagating, coplanar light sheets;

wherein the light sheets are coplanar with the focal plane; wherein the focal plane is illuminated by only one light sheet at a time;

b) detecting by a detection unit multiple images of a specimen cross-section positioned in the focal plane, wherein the detecting is performed during the alternate illumination of the focal plane with the two counter-propagating, coplanar light sheets, wherein each of the multiple images is detected while only one of the coplanar light sheets is illuminating the focal plane; wherein the detection unit has a detection axis perpendicular to an axis of propagation of the light sheets;

and

c) image fusion processing the multiple images of the specimen cross-section, wherein the multiple images were detected during the alternate illumination of the focal plane with the two counter-propagating, coplanar light sheets, to produce a reconstructed image representation of the specimen cross-section having improved image quality.

10. The method of claim 9 further comprising pivoting the direction of propagation of the light sheets in the focal plane while detecting the image.

11. The method of claim 10 wherein the pivoting oscillates through +/−10 degrees while detecting the image.

12. The method of claim 10 wherein the pivoting oscillates at a frequency on the order of 1 kHz.

13. The method of claim 9 further comprising alternately illuminating the focal plane with an additional pair of two counter-propagating, coplanar light sheets such that the focal plane is illuminated by only one light sheet at a time.

14. The method of claim 9 further comprising detecting an image of an opposite side of the specimen cross-section positioned in the focal plane while only one of the coplanar light sheets is illuminating the focal plane.

15. The method of claim 9 further comprising adapting the light sheets using feedback from light transmitted through the specimen.