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seen Aug 17 at 8:50

Jun
26
comment How to measure the wavelength of a laser pointer?
@Floris, well, if you know the capacity of your CD... In any case, the screen might have a better defined pitch, and the optical disks are a better grating (better resolution).
Jun
25
revised Laser Transverse/Longitudnal Modes
Added a note on the difference between (m,n) and q indices
Jun
25
comment How to measure the wavelength of a laser pointer?
Floris, which part of the iPhone was used as the grating? :)
Jun
25
awarded  Yearling
Jun
25
awarded  Revival
Jun
24
comment How to measure the wavelength of a laser pointer?
You can use a CD or DVD as such diffraction grating. Here is a great description: link. The nominal CD grating pitch is 1.6 um, DVD 0.74.
Jun
24
revised Laser Transverse/Longitudnal Modes
Original questions answered explicitly
Jun
24
answered Entangled Photon (laser pointer)
Jun
24
answered Laser Transverse/Longitudnal Modes
Jun
24
accepted Do stars produce spatially coherent light? Why?
Jun
21
comment Do stars produce spatially coherent light? Why?
Ah, that's a good point. I completely forgot that a single photon will interfere with itself, thus two different photons don't have to be coherent. Thanks guys!
Jun
21
awarded  Critic
Jun
21
asked Do stars produce spatially coherent light? Why?
Jun
21
comment If photons move linearly, what's actually stopping them from passing through a microwave oven mesh?
A rather misleading answer IMO. "The size of electromagnetic wave is equal roughly to the size of device which emits it." An optical wavelength is not equal to the size of a laser. Nor is it close to the size of the emitting particle: a CO2 laser emits 10.6 um light, with the CO2 molecule having the size of 230 pm. And the antennas consist of atoms, too. Also, each single photon can be treated as a wave (Young experiment), so it's misleading to say that "a wave consists of many photons".
Jul
2
awarded  Curious
May
27
revised How to specify BRDF measurement
Added information about Zemax capabilities
May
27
comment How to specify BRDF measurement
@CarlWitthoft: If I do not measure polarization, how can I distinguish between high and low reflectivity of s and p polarizations close to Brewster angle? The system is working with a laser, so polarization is relevant there. BTW, thanks for the link, I sent them the request.
May
27
comment How to specify BRDF measurement
@StefanBischof: We need to measure the construction materials, which have been chosen for their mechanical, not optical properties. Moreover, to make things cheep, we do not specify the surface properties to the suppliers. That's why we do not know much about them a priori. An extruded tube can have a very smooth surface while a milled part can be quite rough.
May
26
asked How to specify BRDF measurement
May
7
accepted Anodized aluminium reflectivity at 10.6 um