Test 5 - Phase-contrast, optical parts, light sources

A black body or blackbody is ....

• a body that at any temperature emits absolutely no light in any spectral range

• a body that at any temperature absorbs absolutely all radiation falling on it, regardless of the spectral composition of this radiation

• a body that at any temperature absolutely does not emit, reflect or absorb radiation regardless of the spectral composition of that radiation

• a body that at any temperature emits only thermal radiation in a spectral range that is not visible to the human eye

Select the correct statements about LEDs:

• The half-width of a typical quasi-monochromatic LED spectrum ranges from 20 to 70 nm

• The spectrum of LED radiation is comparable in width to the spectrum of laser radiation

• Most of the energy of UV and visible light is not distributed evenly across the spectrum, but is concentrated in spectral lines between which there is a continuous background

• LEDs do NOT provide sufficient spectral diversity to allow wavelength selection for optimal excitation of fluorophores spanning the UV, visible, and near IR regions

What is the difference between a halogen lamp and a regular incandescent lamp?

• The filament of a halogen lamp is doped with special components

• Inside the bulb of a halogen lamp there is a special gas - bromine or iodine

• Halogen lamp and incandescent lamp are 2 different names for the same device

• The incandescent lamp has a more even radiation spectrum, which is shifted towards the blue region, relative to the radiation spectrum of the halogen lamp.

Select the spectrum of the phase diffraction grating

• 
• 

What is in the image?

• Two phase diffraction gratings

• Two amplitude diffraction gratings

• On the left a phase grating and on the right an amplitude grating

• On the left an amplitude grating and on the right a phase grating

Phase contrast may be accompanied by the following artifacts

• the appearance of pseudo volume in a flat sample

• an optical artifact known as a "halo" or "ghosting"

• phase contrast transition in large phase samples

• inversion of the real colours of the object

What will an extended phase object look like in positive phase contrast?

• 
• 
• 
• 

Select the correct statements

• With positive phase contrast, the phase ring introduces an advance of π/2 for forward waves

• With positive phase contrast, the phase ring introduces a π/4 lag for the diffracting waves

• With negative phase contrast, the colors are inverted relative to positive phase contrast

• With positive phase contrast, the color of an object depends only on its refractive index and does not depend on its thickness

• Positive phase contrast, in contrast to negative phase contrast, allows visualization of colored objects

Why is the illuminating aperture in the form of a ring?

• The ring is easy to produce

• In such a case the diffraction orders overlap minimally

• There is no reason, you can use any other form

• In such a case the phase shift of the transmitted radiation is reduced