1. Theory of light Flashcards
Collimator
device for changing the diverging light or other radiation from a point source into a parallel beam (directs the light onto specimen in microscope)
Gray pictures are a sign that what method was used?
Transmission
Transmittance in a medium is defined by
ratio of transmitted radiant power to incident radiant power.
Aperture
Aperture can be defined as the opening in a lens through which light passes to enter the camera - adjustment is important for contrast, illumination and dept of field
Phase shift
The light that passes a specimen might change phase (or speed)
Phase contrast microscopy
important to see animals in their natural environment. Relies on the phase shift that occurs when light passes through different mediums so the outcome has high contrast
Objectives
The lens part of the microscope
Numerical aperture/magnifications
often referred to as the resolution. Tells you how many times your specimen will be magnified (not 1:1). Magnification is fixed, but numerical aperture can be increased by increasing the angle of the light (sin(μ))
Glass cover thickness
Tells you how thick your glass should be. Often we can’t get a glass that is the correct thickness
Corrector ring
Allows you to change the focus depending on how thick your glass cover is
Explain (NA) = n(sin μ)
The numerical aperture is equal to the refractive index (depends on oli, water or air) times sin of the angle the light forms (max 90*). We can increase μ by decreasing our working distance (the closer the light gets, the wider the base angle will be)
refractive index
How much a substance will refract light. These are set values for each material. Air’s refractive index is 1.
D
Resolution, the smallest resolvable distance between two objects
Explain d = λ / 2 × NA
The resolution is equal to the wave length divided by 2 multiplies with the numerical aperture
Diffraction
Light is sent awry when it hit obstacles or slits. The smaller the obstacle, the bigger the diffraction
