Final answer:
The phase-contrast or interference microscopy technique increases the sharpness of high contrast boundaries by manipulating the phase of light and using interference effects to enhance contrast in microscopy.
Step-by-step explanation:
To increase the sharpness of high contrast boundaries in microscopy, phase-contrast or interference microscopy techniques are often employed. These methods enhance contrast by utilizing the wave characteristics of light, particularly interference effects. Phase-contrast microscopy, for example, manipulates the phase of light waves passing through a specimen. It introduces a half-wavelength shift to light entering the specimen, which allows it to capture small differences in refractive index.
This technique is especially useful when observing live, unstained specimens, as it produces bright images on darker backgrounds without the need for dyes or fluorophores. Structures within the specimen cause refraction and interference which result in high-contrast, high-resolution images. This is achieved through different paths in the sample causing light waves to emerge out of phase and interfere differently, thereby enhancing the contrast of the observed object against the background.