Can Two Independent Lasers Create an Interference Pattern?

[maxentropy]

If a laser was shined at a device to measure the amount of photons striking it and then another laser was shined perpendicular to first laser, would the reading on the meter change?

 

[Drakkith]

No, the photons will not interfere with each other.

 

[euquila]

I imagine it would because destructive interference at that point would result in a lower detection rate.

 

[euquila]

No, the photons will not interfere with each other.

Sorry for double post but I just saw your post. Why would they not interfere with each other if the waves are 90° out of phase?

 

[Drakkith]

Sorry for double post but I just saw your post. Why would they not interfere with each other if the waves are 90° out of phase?

Let's be clear. I thought the OP was talking about shining a beam THROUGH another beam. Is that what you were thinking?

 

[Redbelly98]

Sorry for double post but I just saw your post. Why would they not interfere with each other if the waves are 90° out of phase?

You seem to have some misconceptions.

For starters, nobody said the two waves were 90° out of phase, only that the two beams were perpendicular to each other.
Secondly, two different & independent lasers would not maintain a constant phase difference.
Third, as I interpret the OP, the second laser beam is not shining on the detector, so the second laser has no effect on the detector reading.

 

[maxentropy]

That is correct Drakkit. And would the angle matter? What I was asking was would the beams interfere with each other? and the second laser was not shining on the detector

 

[Redbelly98]

That is correct Drakkit. And would the angle matter?

As long as the 2nd beam is not actually shining on the detector, then no the angle would not matter.

 

[maxentropy]

So the second laser would not affect the reading from the first, correct?

 

[Drakkith]

So the second laser would not affect the reading from the first, correct?

Correct.

 

[euquila]

From what I understand, this is the situation (ignore the dots as I'm using them for spacing):
1...2
\.../
.\.../
..\../
...\/
----------------------- Detector

Beam 1 and 2 form and angle of 90° between each other and 45° to the detector.

Would there not be interference where the two beams meet at the detector?

Can you explain to me (never took optics) why would the phase difference between two lasers not be time invariant?

Thanks in advance

 

[sophiecentaur]

Why should it be? The two oscillators are not synchronous.

 

[Redbelly98]

From what I understand, this is the situation (ignore the dots as I'm using them for spacing):
1...2
\.../
.\.../
..\../
...\/
----------------------- Detector

My understanding of the setup was more like this:

       1
       |
       |
2 ---+---->
       |
       |
       |
       V
     ---- detector

 

[euquila]

Right. There is no interaction with matter where they intersect. Thank you for clarifying!

 

[sophiecentaur]

Whatever the physical layout is, the two lasers would be independent of each other so you would not get any interference effects. Even if they were synchronised and the beams crossed each other at right angles, any interference would only occur where the beams cross and they would emerge from this overlap zone totally unaffected. The principle of superposition applies - field vectors add arithmetically in a linear medium.

Any interference pattern will only occur in regions where both beams are present.