3B Scientific Laser Optics Supplemental Set - Manual (Page 19)

19
E4a Reflection of light rays on convex mirror –
rays are parallel to optical axis
(U17300)
The reflected rays, parallel to the optical axis, appear
to start from one point on the right side behind the
mirror. This point is referred to as the figure focus. The
length of line VF determines the focal length f of the
mirror. The radius of curvature can be obtained from
the next formula.
f
r
=
2
The distance of the centre of curvature S is two times
longer than the distance of the focus F.
E4b Reflection of light rays on convex mirror –
rays are non-parallel to optical axis
(U17300)
The axis
ϕ
which is perpendicular to the optical axis
and passes through the focus is referred to as the focal
plane of the convex mirror. If parallel rays impinge
the mirror, they are scattered in such a way that they
appear to start from one point of the plane
ϕ
. In the
case of incidence rays parallel to the optical axis this
point belongs to the axis.
E5a Refraction of light passing air-glass boundary
(U17300, transparency F)
If light passes through one optical medium character-
ized by refraction index n
1
into the other with refrac-
tion index n
2
its direction is changed by Snell’s law:
n
1
sin
α
= n
2
sin ß
where
α
is an incidence angle in the medium n
1
and
ß is an angle of refraction in the medium n
2
. The angles
are measured from the normal to the planar boundary.
E5b Apparent depth of objects
(U17301)
You can build up the model of observing the depth of
objects in water or glass from air.
Air
Acrylic
Pencil
Acrylic
Air