Microscopy Techniques Flashcards
7 cards from real Histology Certification practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Microscopy Techniques flashcards as text
What is the primary advantage of phase contrast microscopy over bright-field microscopy when viewing unstained cells?
Answer: It converts phase differences into amplitude differences, enhancing contrast
Phase contrast microscopy converts subtle differences in refractive index into visible contrast differences, allowing unstained living cells to be visualized clearly.
In confocal laser scanning microscopy, what is the purpose of the pinhole aperture?
Answer: To exclude out-of-focus light and improve axial resolution
The pinhole aperture in confocal microscopy blocks out-of-focus fluorescent light, enabling optical sectioning and high-resolution 3D reconstruction.
Which type of objective lens provides the highest numerical aperture and requires immersion oil?
Answer: 100x oil immersion
The 100x oil immersion objective achieves numerical apertures up to 1.4 by using immersion oil that matches the refractive index of glass, maximizing light collection.
What does the term 'parfocal' mean in the context of microscope objectives?
Answer: Objectives remain approximately in focus when switching between them
Parfocal objectives require only minor refocusing when switching magnifications because they are designed to maintain approximately the same focal plane.
In transmission electron microscopy (TEM), what is the function of the objective aperture?
Answer: To improve contrast by blocking scattered electrons
The objective aperture in TEM blocks highly scattered electrons, improving image contrast by allowing only minimally scattered electrons to contribute to the final image.
Which microscopy technique is best suited for imaging surface topography of a specimen at nanometer resolution?
Answer: Scanning electron microscopy (SEM)
SEM generates detailed three-dimensional surface images by detecting secondary electrons emitted from the specimen surface, providing nanometer-scale topographical resolution.
What is the Rayleigh criterion for the limit of resolution in optical microscopy?
Answer: d = 0.61λ / NA
The Rayleigh criterion states that the minimum resolvable distance is d = 0.61λ/NA, where λ is the wavelength of light and NA is the numerical aperture.