scholarly journals On the Interpretation of Phase-Contrast Images

1960 ◽  
Vol s3-101 (56) ◽  
pp. 465-473
Author(s):  
W. H. STEEL ◽  
Y. T. TCHAN
Keyword(s):  
Phase Contrast ◽  
Simple Theory ◽  
Phase Plate ◽  
Phase Contrast Microscopy ◽  
Extended Theory ◽  
Contrast Microscopy ◽  
Overlap Factor

It is shown that the simple theory of phase-contrast microscopy may be extended to take some account of the size of the object by the introduction of an ‘overlap factor’ which expresses the fraction of the diffracted light that passes through the phase-changing region of the phase plate. The extended theory can explain observed effects that cannot be explained even qualitatively if overlap is ignored. The overlap factor is given for disk-shaped objects and an annular phase plate.

A Simple Method for Phase-contrast Microscopy: Improvements in Technique

1949 ◽  
Vol s3-90 (11) ◽  
pp. 323-329
Author(s):  
JOHN R. BAKER ◽  
D. A. KEMPSON ◽  
P.C. J. BRUNET
Keyword(s):  
Phase Contrast ◽  
Magnesium Fluoride ◽  
Phase Plate ◽  
Dark Phase ◽  
Phase Contrast Microscopy ◽  
Simple Method ◽  
Contrast Microscopy ◽  
Bull's Eye ◽  
Made In

The following are the main improvements that we have made in the method of phase-contrast microscopy described by Kempson, Thomas, and Baker (1948): 1. No bull's-eye condenser is used. The illuminant is an electric bulb with a ‘porcelain-processed’, ‘flashed white’, or ‘opal’ surface. 2. No oiled paper is placed over the illuminating annulus. 3. The thickness of the deposit of magnesium fluoride on the phase-plate is controlled by observations on the interference colours given by surface reflections. 4. Positive (dark) phase-contrast is preferred for most purposes to negative (bright).

Influences of Spiral Phase Plate′s Parameters on Spiral Phase Contrast Microscopy

2012 ◽  
Vol 32 (4) ◽  
pp. 0411002
Author(s):  
王炯 Wang Jiong ◽  
张雨东 Zhang Yudong ◽  
李国俊 Li Guojun ◽  
罗先刚 Luo Xiangang ◽  
张小军 Zhang Xiaojun ◽  
...  
Keyword(s):  
Phase Contrast ◽  
Phase Plate ◽  
Phase Contrast Microscopy ◽  
Contrast Microscopy ◽  
S Parameters ◽  
Spiral Phase Plate ◽  
Spiral Phase

Multiple-beam interference microscopy

1952 ◽  
Vol 211 (1105) ◽  
pp. 240-254 ◽  
Keyword(s):  
Phase Contrast ◽  
Incident Light ◽  
Wedge Angle ◽  
Zero Order ◽  
Interference Microscopy ◽  
Phase Plate ◽  
Phase Contrast Microscopy ◽  
Multiple Beam ◽  
Contrast Microscopy ◽  
Diffracted Waves

Many objects examined under the microscope influence the phase but not the amplitude of the incident light, and the image is of such poor contrast that much structural detail is lost. Multiple-beam interference, two-beam interference and phase-contrast microscopy all present means of overcoming this difficulty. The diffraction theory of multiple-beam interference microscopy, which has hitherto been neglected, is here developed by regarding the object under study as a phase grating; a comparison is then made with the two other forms of microscopy. In phase-contrast microscopy (Zernike 1935 a, b , 1942) the effective phase and amplitude of the zero-order beam are suitably changed by an absorbing phase plate situated in the rear focal plane of the objective or in an equivalent plane. Two-beam interference microscopy, such as is encountered in modified Michelson interferometers, closely resembles phase-contrast microscopy, because a coherent wave is superimposed upon the diffracted waves from the object, thereby effectively altering both the phase and amplitude of the zero-order beam (Berti 1948, 1951). With multiple-beam interference microscopy (Tolansky 1948), however, the phase and amplitude of each diffracted beam are changed to an extent determined by the phase and amplitude of all the other diffracted beams. This relationship prevents one from modifying a given beam without influencing all the others. When the interferometer is viewed in reflexion these modified diffracted waves are superimposed upon a coherent background, so that, when the interferometer reflectivity is low, the arrangement produces effectively two-beam interference. As the lateral structure of the object becomes finer, the image formed by multiple-beam interference becomes a less faithful portrayal of the object structure; the extent of this infidelity is enhanced as the reflectivity, gap and wedge angle of the interferometer are increased. The advantage of multiple-beam interference is the high accuracy with which phase differences within the object can be measured.

Low-power Phase-contrast Microscopy without a Condenser

1950 ◽  
Vol s3-91 (13) ◽  
pp. 109-110
Author(s):  
D. A. KEMPSON
Keyword(s):  
Low Power ◽  
Focal Plane ◽  
Phase Contrast ◽  
Phase Plate ◽  
Phase Contrast Microscopy ◽  
Contrast Microscopy

With those low-power objectives in which a phase-plate can be placed near the back focal plane, phase-contrast microscopy can be obtained without the use of any condenser. The illuminating annulus is placed in the conjugate focus of the phaseplate.

A Simple Method for Phase-Contrast Microscopy

1948 ◽  
Vol s3-89 (7) ◽  
pp. 351-358
Author(s):  
D. A. KEMPSON ◽  
O. L. THOMAS ◽  
JOHN R. BAKER
Keyword(s):  
Phase Contrast ◽  
Phase Plate ◽  
Phase Contrast Microscopy ◽  
Simple Method ◽  
Contrast Microscopy ◽  
Annular Source

A method of phase-contrast microscopy is described, not involving the use of special objectives or condensers. A method for making the phase-plate carrying a raised annulus is described. A large annular source of light is focused by the condenser of the microscope in a plane slightly below the object. The phase-plate is placed in the conjugate focus of this plane, just above the back lens of the objective.

scholarly journals Rough Dental Implant Surfaces and Peri-Implantitis: Role of Phase-Contrast Microscopy, Laser Protocols, and Modified Home Oral Hygiene in Maintenance. A 10-Year Retrospective Study

2021 ◽  
Vol 11 (11) ◽  
pp. 4985
Author(s):  
Gianluigi Caccianiga ◽  
Gérard Rey ◽  
Paolo Caccianiga ◽  
Alessandro Leonida ◽  
Marco Baldoni ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Phase Contrast ◽  
Vertical Movement ◽  
Subgingival Plaque ◽  
Phase Contrast Microscopy ◽  
Implant Surface ◽  
Total Percentage ◽  
Contrast Microscopy

The aim of this study was to evaluate two different kinds of rough implant surface and to assess their tendency to peri-implantitis disease, with a follow-up of more than 10 years. Data were obtained from a cluster of 500 implants with Ti-Unite surface and 1000 implants with Ossean surface, with a minimum follow-up of 10 years. Implants had been inserted both in pristine bone and regenerated bone. We registered incidence of peri-implantitis and other causes of implant loss. All patients agreed with the following maintenance protocol: sonic brush with vertical movement (Broxo), interdental brushes, and oral irrigators (Broxo) at least two times every day. For all patients with implants, we evaluated subgingival plaque samples by phase-contrast microscopy every 4 months for a period of more than 10-years. Ti-Unite surface implants underwent peri-implantitis in 1.6% of the total number of implants inserted and Ossean surface implants showed peri-implantitis in 1.5% of the total number of implants. The total percentage of implant lost was 4% for Ti-Unite surfaces and 3.6% for Ossean surfaces. Strict control of implants leads to low percentage of peri-implantitis even for rough surfaces dental implants.

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