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Thread: Again a laser discussion
face BY : Bob Blick email (remove spam text)

> How do you measure them Vasile? Mine were bought
> from an associate who bought a big batch of them
> from Asia as 5mW bright red. They are supposed to
> be Russian ones. VERY bright!

Hi Roman,

5mW is a very standard maximum rating for the laser diodes typically used
in laser pointers. They work quite well at 5mW at reasonable temperatures
but don't last very long above that.

However, when the diode is putting out 5 mW, you will typically get only 2
or 3 mW out of the laser pointer, because the beam is usually clipped and
goes through uncoated optics. It's difficult not to clip the beam because
the output of laser diodes is an ugly fan-shape, quite unlike the
pencil-thin beam you associate with lasers. You have to put a collimating
lens in front of it, and building it all in a tiny pointer, you can't get
all the beam.

The reason these seemed so bright to you is the wavelength. A few years
ago laser pointers were 670-680 nM, a very dark red. Nowadays they are
more like 650 nM, and the eye is a lot more sensitive to it.

Cheerful regards,

Bob Blick

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Subject (change) Again a laser discussion

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