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
In structured illumination microscopy (SIM), how is resolution beyond the diffraction limit achieved?
Answer: By using patterned illumination to generate Moiré fringes that encode high-frequency spatial information
SIM projects a sinusoidal illumination pattern onto the specimen; the Moiré effect shifts high-frequency sample information into the detectable passband, allowing computational reconstruction of images with ~2× improved resolution.
What is photoactivated localization microscopy (PALM), and what type of fluorophores does it require?
Answer: A single-molecule localization technique using photoactivatable or photoswitchable fluorescent proteins
PALM activates sparse subsets of photoactivatable fluorescent proteins (e.g., PA-GFP, mEos) stochastically, precisely localizes each molecule, and accumulates thousands of localizations to reconstruct a super-resolution image.
Which type of chromatic aberration causes different wavelengths to focus at different axial distances along the optical axis?
Answer: Axial (longitudinal) chromatic aberration
Axial chromatic aberration occurs because glass has different refractive indices for different wavelengths, causing short wavelengths to focus closer to the lens than long wavelengths.
In light sheet fluorescence microscopy (LSFM), what is the key advantage over confocal microscopy for imaging large specimens?
Answer: Selective plane illumination reduces photobleaching and phototoxicity by exciting only the imaged plane
LSFM illuminates only the focal plane from the side with a thin sheet of light, dramatically reducing photobleaching and phototoxicity compared to confocal microscopy, which illuminates the entire depth during each acquisition.
What is the Köhler illumination technique designed to achieve in bright-field microscopy?
Answer: Provide even, glare-free illumination by placing the lamp filament conjugate at the back focal plane of the condenser
Köhler illumination focuses an image of the lamp filament at the front focal plane of the condenser, so the specimen plane receives uniform, defocused illumination that eliminates the lamp structure from the image.
Which specimen preparation artifact in TEM is characterized by parallel lines across the section caused by imperfect sectioning?
Answer: Chatter
Chatter artifacts appear as periodic parallel lines perpendicular to the cutting direction, caused by vibration or oscillation of the specimen or knife during ultramicrotomy.
In darkfield microscopy, how is the bright central beam of light excluded to produce a dark background?
Answer: By using a central opaque stop in the condenser that blocks direct light so only oblique rays illuminate the specimen
A darkfield condenser uses a central stop that blocks the direct illuminating cone so that only highly oblique rays reach the specimen; only light scattered by the specimen enters the objective, producing a bright image on a dark background.