Ultrasonic wave scanner

• From the perspective of wave optics, the details of the object, that is, the details of the biological specimen, can be regarded as obstacles to the imaging beam. It can change the amplitude, phase and intensity distribution of the coherent beam.

• From the perspective of spectrum conversion of transform optics, object details can be regarded as a collection of different spatial information. It can change the spatial spectrum of light information.

• Under the microscope, the optical dense material, the optical thin material and the unstructured medium of the specimen detail have different refractive indices. Therefore, when the coherent beam passes through the optical dense material (t), it will inevitably produce diffraction, which will prolong the optical path and delay the phase (Figure 10-21p). Then the phase difference between diffracted light (P) and direct light (S) appears d/λ. However, the absorption degree of the specimen is similar, so the amplitude does not change, that is, the light intensity finally changes. When the direct and diffracted light arrive at the image plane for overlapping imaging, the amplitude of the synthesized wave is almost similar to that of the direct light passing through the unstructured medium, that is, its light intensity is similar. This is an ultrasound scanner with very little contrast in an unstained specimen under a normal microscope

Dark differ

• When the refractive index of the object is greater than that of the medium, the direct light through the conjugate surface is absorbed by 80% and the brightness becomes dark. The phase of the diffracted light has been delayed by 1/4 wavelength after passing through the object, and then the electrolyte on the compensation surface of the in-phase plate has been delayed by another 1/4 wavelength. Because THE TWO BEAMS ARE DIFFERENT IN PHASE (1/2 WAVELENGTH DIFFERENCE), THE RESULTANT WAVE HAS THE SAME AMPLITUDE AS THE TWO, SO THE LIGHT IS DIMMER.

• At the same time, the optical path of the diffracted light through the unstructured medium is only delayed by the dielectric at the compensation surface by l / 4 wavelength. The result is that the intensity of light passing through a light-dense material is much more diminished than the intensity of light passing through an unstructured medium (background). The contrast between the details of the specimen under the phase contrast microscope is increased. The light dense structure is much darker than the background. This contrast is called dark contrast or positive contrast.

Ming differ

, if the conjugate phase plate surface coating is the reduction material, delay the direct light 1/4 wavelength, and the compensation surface is a material suction light, the result is the direct light and diffraction of light in the same phase (diffraction light through the object phase delayed 1/4 wavelength), the composite wave amplitude of the sum of the two, the result object is bright and the background is dark, this is called Ming or negative difference.

Phase contrast microscopy experimental methods and procedures Ultrasonic scanner

Remove the original concentrator and objective lens, install the concentrator and objective lens respectively, and turn the turntable to the position marked "0". Dimmer with a 10× phase contrast objective.

• Adjust the light source.

• Off-axis adjustment Remove the eyepiece and replace it with the on-axis adjustment telescope. Move the telescope up and down until you can see the phase plate ring in the objective.

• Put the eyepiece back. Remove the hinge and adjust the telescope. Put the eyepiece back to observe. When changing the different magnification of the contrast objective, each time to adjust as above.