I didn't know people could see infrared..
People cannot see infrared light. That small red dot of light on the lens is
not the actual beam. The actual beam in the IR range is much more intense.
While the laser is working, take a CCD video camera and look at how the camera
sees the light.

There is a small red light
on, but that's just an indicator to tell you NOT TO LOOK at the
laser... and the difference between the cd and dvd laser isn't
intensity, it's size.

The BIGGEST and correct difference is wavelength. DVD lasers operate at a
shorter wavelength/higher frequency in the electromagnetic spectrum. It's high
enough to be visible. CD lasers operate at a longer wavelength/lower frequency
below the visible spectrum.

The tighter pit density is actually made possible by the fact that the beam
frequency is higher. The higher the frequency of the laser beam, the more
information it can carry at once. This is translated physically on a CD-sized
disc as more pits per centimeter, and more pits for a CD-sized DVD consequently
means a tighter track width to accomodate the higher pit density on the disc.

What happens upon powerup, or interlock close. is the laser starts out with
a weak beam for CD, and tries to focus, and then it gets bright and tries to
focus. The brightness of the beam lights all of the parts surrounding the
lens. like a laser pointer brightness. then CD brightness is typical.

Some players have the lasers go into DVD mode first, then CD mode. Others do
it vice versa.

If when in DVD detecting mode, and the laser is dim, or is not there at all,
but only there on CD, the diode, or driver circuitry is bad.

Just because the pickup cannot read a DVD doesn't mean that the laser is dim or
not there at all. In many cases when the pickup goes south, the actual laser
may still be functional but the photo sensor that is supposed to translate the
light into electrical signals goes bad. There are situations, however, where
the laser does become marginal, usually through wear, either premature or
through normal use. Other times a failure can occur through dust accumulation
inside the pickup. Then there are times where the optical pickup isn't at
fault, but someone makes the mistake in thinking that the pickup is bad purely
from the symptoms they observe, like the symptoms arising from a blown
microfuse with the DSP laser focus servo in the Sony DVP-S350, DVP-S360, and
DVP-S560. - Reinhart