Phase contrast microscope

A phase contrast microscope comprising:

• an illumination optical system for illuminating a specimen under inspection;
• an aperture arranged at a pupil of said illumination optical system;
• an imaging optical system for forming an image of the specimen;
• a phase plate arranged near a pupil of said imaging optical system, said pupil of the imaging optical system being arranged at a conjugate position with the aperture with respect to a specimen plane on which said specimen situates, said phase plate including an element which introduces an electrically variable phase difference between a zero order diffracted beam and higher order diffracted beams, and substantially transparent electrodes arranged on opposite sides of said element such that a voltage is applied across the element via the electrodes;
• and
• a controlling means for adjusting a value of said voltage applied across said element to set said phase difference to such values that a dark contrast image, a bright contrast image and a high resolution image are selectively observed under a same condition.

A phase contrast microscope comprising:

• an illumination optical system for illuminating a specimen under inspection, the specimen being disposed at a specimen plane;
• an aperture arranged at a pupil of said illumination optical system;
• an imaging optical system for forming an image of the specimen at an imaging plane;
• a phase plate arranged near a pupil of said imaging optical system, said pupil of the imaging optical system being arranged at a conjugate position with said aperture with respect to the specimen plane;
• an image pick-up means provided at the imaging plane for picking-up the image to produce an image signal;
• a storing means for storing said image signal produced by said image pick-up means;
• and
• a signal processing means for processing the image signal read out of said storing means;
• wherein said phase plate is constructed to give phase differences which have substantially a same amount but have opposite signs, two images at said phase differences comprising a dark contrast image having an intensity distribution Ia and a bright contrast image having an intensity distribution Ib and are separately picked-up by said image pick-up means and stored in said storing means, and an image of a difference between said two images is derived as a phase contrast image having an intensity distribution Ia-Ib.

A phase contrast microscope comprising:

• an illumination optical system for illuminating a specimen under inspection, the specimen being disposed at a specimen plane;
• an aperture arranged at a pupil of said illumination optical system;
• an imaging optical system for forming an image of the specimen at an imaging plane;
• a phase plate arranged near a pupil of said imaging optical system, said pupil of the imaging optical system being arranged at a conjugate position with said aperture with respect to the specimen plane, said phase plate comprising a liquid crystal and substantially transparent electrodes arranged on both sides of the liquid crystal;
• an image pick-up means provided at the imaging plane for picking-up the image to produce an image signal;
• a storing means for storing said image signal produced by said image pick-up means;
• and
• a signal processing means for processing the image signal read out of said storing means;
• wherein said phase plate is constructed to give phase differences which have substantially a same amount but have opposite signs, two images at said different phase differences are separately picked-up by said image pick-up means and stored in said storing means, an image of a difference between said two images is derived as a phase contrast image, at least one of said transparent electrodes of the phase plate is formed as a ring and a ratio of a radius r of a center circle of the ring and a radius R of the pupil of the imaging optical system is set to 1>r/R>0.5.

A phase contrast microscope comprising:

• an illumination optical system for illuminating a specimen under inspection, the specimen being disposed at a specimen plane;
• an aperture arranged at a pupil of said illumination optical system;
• an imaging optical system for forming an image of the specimen at an imaging plane;
• a phase plate arranged near a pupil of said imaging optical system, said pupil of the imaging optical system being arranged at a conjugate position with said aperture with respect to the specimen plane;
• an image pick-up means provided at the imaging plane for picking-up the image to produce an image signal;
• a storing means for storing said image signal produced by said image pick-up means;
• a signal processing means for processing the image signal read out of said storing means to produce a phase contrast image;
• and
• a calculating means for effecting a deconvolution of the phase contrast image obtained by said signal processing means;
• wherein said phase plate is constructed to give phase differences which have substantially a same amount but have opposite signs, two images at said different phase differences are separately picked-up by said image pick-up means and stored in said storing means, and an image of a difference between said two images is derived as said phase contrast image.