Method of increasing the depth of focus and or the resolution of light microscopes by illuminating and imaging through a diaphragm with pinhole apertures

• US 3,926,500 A
• Filed: 12/02/1974
• Issued: 12/16/1975
• Est. Priority Date: 12/02/1974
• Status: Expired due to Term

• Current Assignee: Albert Frosch, Hans Erdmann Korth
• Original Assignee: Albert Frosch, Hans Erdmann Korth
• Inventors: Frosch, Albert, Korth, Hans Erdmann
• Primary Examiner(s): Smith, Alfred E.
• Assistant Examiner(s): Henry, Jon W.
• Application Number:
  US05/528,965
• Time in Patent Office: 379 Days
• Field of Search: 350/273,274,275,266,91,9,14,15,19,88,17,6,7,285 356/203,125,126 178/7.6
• US Class Current: 359/235
• CPC Class Codes: G02B 21/082 for incident illumination only
• CPC Class Codes: G02B 27/0075 with means for altering, e.g. increasing, the depth of field or depth of focus
• CPC Class Codes: G02B 27/58 Optics for apodization or superresolution; Optical synthetic aperture systems

Abstract

In order to increase the depth of focus of a high resolution microscope objective a diaphragm having small openings 25, 26 is rotatably mounted in plane 13 which is conjugate to object plane 12. Object 11 is illuminated (scanned) through semi-transparent mirror 19 and said diaphragm in such a way that light passing through said openings is sharply focused only on areas lying near to, or in object plane 12 within the depth of focus range of objective 2. Only light scattered or reflected from such areas passes through said openings substantially without losses and after passing through lens 20 provides a clear image of high contrast of those areas of object 11 which lie within the depth of focus of lens 2. Light coming (reflected, scattered) from all other areas of object 11 lying outside the depth of focus is subject to substantial losses so that no image appears at 22. If object 11 is moved cyclically with say 50 cps vertically to plane 12 so that all object points pass at least once through the depths of focus range of lens 2 a clear image of high contrast of all object points is visible at 22.

Claims

1. Apparatus for producing magnified images of non-flat object surface areas with enhanced depth contrast and resolution of detail comprising:

an objective lens;

means containing plural co-planar pinhole apertures, each pinhole aperture for transmitting a beam of light thru said lens to be incident on an object surface and for retransmitting a spot-imaged beam of light returned by said lens after scattering reflection of said incident beam from said surface;

means for shifting focal coordinates of each incident beam in three dimensions relative to said surface; and

means for utilizing light returned through said apertures to form said magnified images.

2. Apparatus according to claim 1 in which said apertures are dimensioned to pass at least zero-th and first order diffraction components of light presented thereto and to form spot images, relative to an area encompassing multiple spots in the focal plane of said lens, which are at least as large as the spot resolution of said lens.

3. Apparatus according to claim 2 in which said means containing said apertures comprises a rotatably mounted multiapertured plate and said means for coordinate shifting comprises means for concurrently rotating said plate and varying the distance between said objective lens and object, thereby varying area and depth focal coordinates of said lens relative to said object surface.

4. Apparatus in accordance with claim 3 in which said coordinate shifting is carried out repeatedly at a rate suited for permitting '"'"''"'"''"'"''"'"'flicker-free'"'"''"'"''"'"''"'"' human viewing of said magnified image.

5. Apparatus in accordance with claim 3 wherein said image forming means includes a partially transmisive/partially reflective element for passing transmitted light unidirectionally to said object surface and for passing retransmitted light unidirectionally from said object surface to an evaluation plane offset and isolated from the path of said transmitted light.

6. Apparatus in accordance with claim 6 wherein said partially transmissive/partially reflective element is parallel and adjacent to said plate, and mounted for co-rotation with said plate by said coordinate shifting means.

7. Apparatus in accordance with claim 6 wherein said plate and element form a plural-layered composite structure inclined at an oblique angle to the optical axis of the objective lens.

8. Apparatus in accordance with claim 7 including a polarizer, for polarizing light transferred to said composite structure for imaging on said object, and means located between said objective lens and structure for altering the polarization of light scattered from said object so as to prevent echoing, and potentially interfering, transfers of light between said object and element.