Recent content by Daniel Petka

Sure, here is the code I used: from numpy.fft import fft2, ifft2, fftfreq import numpy as np from matplotlib import pyplot as plt x = np.linspace(-2,2,2000) xv, yv = np.meshgrid(x, x) fig = plt.figure(figsize=(1,1),frameon=False) gaussian = np.exp(-200*(xv**2 + yv**2))*(np.cos(80*xv)**2)...

Didn't express myself clearly here, sorry. I didn't refer to the delta function when I said that the integral cancel, but to the plane waves. In 1D, you can visualize the integral as area under the curve and if there are equally many positive as negative value, which would be the case if you...

Yes, this was my point. The lens just brings the far field to a focal plane. The Fourier Transform happens in the far field. The Fourier Transform of a plane wave is a Delta peak in k-space whose coordinates are the k-vector itself. For any other plane wave, the wavelengths or the angles dont...

Thanks for the insight! I think I can pin point the bit that I'm struggling with here: If we're dealing with plane waves, then nothing can cancel the DC wave (normal incidence), So the whole plane should be illuminated by the DC. This doesn't get fixed even when there's an aperature...

I thought about it for a while now.. First of all, the Fourier Transform happens in the far field. People who say that a lens performs a Fourier Transformation are mostly EEs (like me) who think in terms of components. This is fine, but it's not Real understanding. Through propagation alone, it...

Sorry, my bad. Should be fixed now. This is gibberish without images (possibly even with images) The question is: Why do plane waves get transformed into points in the far field?

If the distance between the input and the output screen d is large enough, then for a plane wave (with some spatial frequencies vx and vy) at the input, the spot at the output will be a point. But if the plane wave is confined (aperature size b in the picture), it's no longer a plane wave... but...

I started by converting the LSM from sum to integral form: $$f(x_c) = \sum_i[S(x_i)-F(x_i,;a,b,...)]^2 to f(x_c) = \int( S(x) - F(x-x_c)^2 dx$$ Since we are not interested in the other parameters (like offset), I assumed that they are fitted correctly and thus ignored them, turning...

Thank you for the reply! This is probably one of those cases where intuition fails

Here is my thought experiment: Let's say I attenuate a very short laser pulse to single photon intensity. Due to the uncertainty principle, I know the time of arrival of the photons, but not their energy. So let's reverse that by splitting the pulse in its spectral components with a diffraction...

Yeah, this is a very interesting phenomenon (Tartini notes) but see my second point, it's not relevant because the difference tone is visible on the spectrogram. Actually, I should be careful phrasing this, it's definitely relevant when it comes to the perception of the sound, but here I'm more...

Hm I'm not sure I understand, the coherence of a single photon is the same as the coherence of the whole beam. That being said, I don't think it makes sense to talk about "photons" before the wave collapses. Btw I think you might like this this video by Huygens Optics, although it's definetly...

Well you are talking about a FP with a very high finesse (so very high mirror reflectivity) Even for such an FP, you can build a laser source that is frequency locked and because that it has a ridiculously low bandwidth (in the MHz or even kHz range or even less) If such laser light resonates...

Well you are talking about a FP with a very high finesse (so very high mirror reflectivity) Even for such an FP, you can build a laser source with a lower bandwidth, usually frequency locked (in the MHz or even kHz range or even less) If such laser light resonates and goes through completely...

If laser light is attenuated to single photon intensities, the frequency doesn't change. I think the FP is a perfect example why photons aren't bullets. How does the photon know that there is a second mirror? It doesn't and yet, it can still pass through both mirrors. That's kind of amazing...