Lecture Nine: Optics 2 Flashcards Preview

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Flashcards in Lecture Nine: Optics 2 Deck (10)
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1

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

2

What happens when we under sample?

We get aliasing

3

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

4

What is a good approximation of an airy disk?

A gussian function

5

What can cause spherical abberation?

Mismatch between emersion medium and mounting medium

6

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)

7

Should everything be sampled at the diffraction limit?

Depends on the question

8

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

9

What are the types of filter averaging to remove noise

Mean
Median
Gussian

10

How can the image be restored from PSF?

decovolution