Exam (only question) Flashcards
(40 cards)
In a brightfieldmicroscope, which component ensures that the illumination light is collected and guided onto the specimen?
Condenser lens
In which type of microscopes is the birefringence (anisotropy) of a structure detected?
dt. Bei welcher Art von Mikroskopen wird die Doppelbrechung (Anisotropie) einer Struktur nachgewiesen?
Polarization microscope
Which principle do light microscopes use to form an image visible to the eye under ultraviolet illumination?
Fluorescence
How are field of view and resolution usually related in a microscopic image?
The larger the magnification of the objective, the smaller the field of view.
What physical laws govern photophysics?
The quantization of all energy states as described by quantum mechanics
What is the advantage of fluorescent dyes with a large Stokes shift?
Easier separation of excitation and fluorescence radiation
What are common features of confocal microscopy (CM) and structured illumination microscopy (SIM).
Both increase resolution compared to classical microscopy
What is called deconvolution in microscopy?
The consideration of the effect of the point spread function(PSF) on imaging
What mathematical transformation connects the light fields in the image and aperture planes?
Fourier transform
Which statement about total internal reflection fluorescence microscopy (TIRF) is correct?
Due to the total reflection of the excitation laser light, the fluorescence is excited by an evanescent field within a layer of only 200 nm thickness, so that the axial resolution in TIRF can be very high.
What does the STED stand for in the super-resolution microscopy developed by Stefan Hell?
STED = Stimulated Emission Depletion
What is the advantage of fluorescence lifetime imaging microscopy (FLIM)?
It enables observation of the local environment of the fluorescence molecules.
What is an important advantage of two-photon microscopy over confocal microscopy for in vivo imaging?
The longer wavelength achieves a deeper penetration depth.
What is time-correlated single-photon counting (TCSPC)?
It accumulates single-photon arrival times in a histogram to determine the fluorescence decay time.
How does Raman spectroscopy enable us to make statements about the structure of molecules?
Because certain subgroups of molecules often have well separable and characteristic Raman bands.
What is the main problem with Raman spectroscopy?
The Raman scattering cross section is typically very small.
What role do visualization methods play in modern microscopy?
Visualization of complex 3-dimensional relationships in the sample
By which process can intracellular nanosurgery be realized with laser light in cells that are actually transparent?
Strong focusing of a laser pulse results in optical breakdown at the focus, where an expanding cavitation bubble disrupts the surrounding structures.
Which characteristic of electrons is used for imaging in electron microscopy?
Electrons have at sufficiently high kinetic energy a short wavelength (de-Broglie), which is relevant for the resolution.
Why are the samples for scanning electron microscopy (SEM) often coated with a thin layer of gold?
Because a local charging of the sample by the electron beam must be avoided, as this would have a negative effect on the SEM image.
What is the role of the objective lens and if present the tube lens?
Objective lens and tube lens have to bring all beams from one object point to one corresponding point in the intermediate image plane.
How to reduce the negative influence of chromatic aberrations in a brightfieldmicroscope when working with white illumination light?
By means of apochromatic objective lenses.
Prisms in the optical path of an upright microscope allow for inclined views. Why is this an advantage?
Despite a comfortable body posture, the object table remains horizontally.
What is a disadvantage when using immersion fluid?
Can only be used with special, fluid tight objective lenses.
