why could we see a laser hologram?

[Stanley514]

How could we see a hologram created by lasers if laser beams do not get in our eyes (it could be dangerous)?

[Andy Resnick]

You don't see the illuminating beam (which is the reference when writing the hologram), you see the scattered light which has much lower power.

I suppose if you had a transmission hologram, you could have some 'hot spots':

http://hyperphysics.phy-astr.gsu.edu/hbase/optmod/holog.html

[Dr Lots-o'watts]

A laser beam isn't worse to the eyes than regular light if it's SUFFICIENTLY spread out.

And regular light that is focused can be just as dangerous as a raw laser beam.

[atha]

That's correct.However you are missing sth.The laser beam area is about 0.2 cm^2.
In order to see the hologram,you need to splay the beam.In this case the ratio Power/Area is far less than before(The hologram's area could be 4 cm^2 in case of a coin or even bigger).Hope I helped a bit!

[Stanley514]

you see the scattered light which has much lower power.
I thought that laser hologram is created by pure laser beam in pure air.
Light could be scattered only from some material object?

[cjameshuff]

I thought that laser hologram is created by pure laser beam in pure air.
Light could be scattered only from some material object?

Holograms can't be projected onto thin air...that's purely sci-fi. You need a screen of some kind, the image then appears in front or behind the screen, but can't go past the edge.

There are a couple 3D displays that either project an image into the air using focused laser pulses to make the air itself glow, or give the effect of projecting onto the air with a spinning screen or mirror, and there's tricks that rely on a smoke or mist as a screen, but these are not holograms.