Flashcards in Lecture Nine: Optics 2 Deck (10)
What other practical factors affect resolution and their solutions?
1) Numerical aperture of lens >NA
2) Resolution and Contrast are linked! >contrast
2) Digitalisation: what size pixel? resolution/2.33) Refractive index of mountant match to oil
4) Depth of focus – keep close to cover slip
5) Coverslip thickness – 170 μm or #1.5
6) Noise e.g. photons , instrumentation - >photons
7) Quality of labelling – use controls e.g. blank
What happens when we under sample?
We get aliasing
What is nyquist theorem in imaging?
Nyquist sampling of an image of two points separated by the Rayleigh resolution
Nyquist rate is 2.3 for images unlike voltage
What is a good approximation of an airy disk?
A gussian function
What can cause spherical abberation?
Mismatch between emersion medium and mounting medium
What is the optimal coverslip thickness?
0.17-0.18mm this has the smallest FWHM for a constant light compared to all others. (look at graph of this)
Should everything be sampled at the diffraction limit?
Depends on the question
How is photon noise modulated?
Poisson distribution where mean equals the variance Reduce noise by increasing number of photons e.g. improve labelling, laser intensity, averaging
What are the types of filter averaging to remove noise