Biomedical Engineering Reference
In-Depth Information
(f ) The circle of least confusion is centered
dioptrically
between the image
plane of the vertical meridian and the image plane of the horizontal
meridian. The dioptric distance from the lens is
4.00 D
+
2.00 D
=
3.00 D
2
This means that the circle of least confusion is located 33.33 cm from the lens.
3. (a)
The vertical meridian of the lens has a power of
+
5.00 D and the horizon-
7.00 D. The image focused by the stronger
horizontal meridian will be closest to the lens.
( b) A vertical line is formed closest to the lens. At the plane where the object's
horizontally diverging light rays are focused by the stronger horizontal
meridian, the vertical rays have not yet focused. These out-of-focus rays form
a vertical line with fuzzy upper and lower edges. The right and left edges of
this line are in focus, however, because the horizontal meridian is in focus.
(c)
L
tal meridian has a power of
+
′
=
L
+
F
(100)(1.00)
−
⎡
⎥
⎤
⎥
′
=
L
+
7.00 D
25.00 cm
′
=
+
L
3.00 D
1
l
′
L
=
′
(100)(1.00)
l
=
+
3.00 D
′
′
=
+
l
33.33 cm
(d) A horizontal line is formed further from the lens. At the plane where the
object's vertically diverging light rays are focused by the weaker vertical
meridian, the horizontal rays are out of focus—they are focused closer to
the lens, at
33.33 cm. These out-of-focus rays form a horizontal line with
fuzzy left and right edges. The upper and lower edges of this line are in
focus, however, because the vertical meridian is in focus.
+
L
′
=
L
+
F
(100)(1.00)
−
⎡
⎥
⎤
⎥
′
=
L
+
5.00 D
25.00 cm
′
=
+
L
1.00 D
1
l
′
′
L
=
(100)(1.00)
l
=
+
1.00 D
′
′
=
+
l
100.00 cm
