Re: question about angle = wavelength / diameter

Hayden wrote:
On May 27, 10:32 pm, OG <o...@xxxxxxxxxxxxxxxxxxx> wrote:
Hayden wrote:

Looks like I can't be of more help.- Hide quoted text -

- Show quoted text -

I think I got it. Angle alpha represents different thing for
the two cases.

Case 1 with lens for aperture size 150mm, angle alpha is
formed by the converging objective and diffraction

Yes - but don't forget that alpha is independent of the focal length of the lens.

Case 2 without lens for aperture size 150mm, angle alpha
is formed by the eyes optics (converging cornea and retinal sensor).

No. Alpha is (more or less) the angular spread of the projected light that an infinitely distant object would produce if passing through the 'hole'.

Case 3 without lens for aperture smaller than wavelength
of light, anglle alpha is formed by theta = lambda/diameter.

'Fraid not. Case 3 is a variant of case 2

What confused me initially was I thought slits wider than
the wavelength of light can still form angle alpha even
if there is no converging objective.

Again, it depends on what you think angle alpha represents. Try getting a textbook and looking at the diagrams.

So for slits
wider than the wavelength of light, the wavefront
just passes thru unaltered except at the edge. This
is why when we see thru a house window at planet
saturn, we can't resolve cassini's division.

Very dumb wrong initial assumptions but everything always
starts with a step.


A few more steps are needed.
.

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