positive phase contrast microscopy

Phase contrast microscopy where the phase plate advances the un-diffracted light relative to the diffracted light by a quarter wavelength (λ/4). Since diffracted light is already retarded by ~λ/4 through interaction with the object, the result is a half-wave phase difference and destructive interference.

Synonyms: positive phase contrast

Related MicroscopyU Article

Positive and Negative Phase Contrast

Depending upon the configuration and properties of the phase ring positioned in the objective rear focal plane, specimens can be observed either in positive or negative phase contrast. This interactive tutorial explores relationships between the surround (S), diffracted (D), and resulting particle (P) waves in brightfield as well as positive and negative phase contrast microscopy. In addition, phase plate geometry and representative specimen images are also presented.