PASCO OS-8500 INTRODUCTORY OPTICS SYSTEM - Manual (Page 57)

012-02744K Introductory Optics System
®
51
Locating Virtual Images
Virtual images can be located using the Virtual Image
Locators. The following procedure is for locating
virtual images formed by a spherical mirror. The
procedure for lenses is similar though, of course, both
image locators are placed on the far side of the lens
from the observer.
Set up the equipment as shown in Figure A1. Notice
that the object must be between the mirror and its
focal point, f, in order for a virtual image to be
formed. Look through Locator A into the spherical
mirror. Move your head from side to side, and notice
how the image of the locator arrow moves.
Look through Locator A into the mirror, so your line
of sight is at a slight angle from the optical axis of the
mirror. The setup should look approximately as in
Figure A2a. Align a straightedge with the image of
the locator arrow as shown in Figure A2b. Now
adjust the position of Locator B until its arrow is
aligned with the straightedge in your line of sight. Do
this in two steps:
➀ Move the Locator laterally (perpendicular to the
optical axis of the bench) to remove half the dis-
tance between the straightedge and the arrow as
shown in Figure A2b, then;
➁ Move the Locator longitudinally (sliding the Com-
ponent Holder along the optical axis of the bench)
to complete the alignment as in A2c.
Check to be sure that the image of the arrow of
Locator A is aligned with the straightedge, and the
straightedge is aligned with the arrow of Locator B.
Now move the straightedge to the other side of the
arrow of Locator A and repeat the process. Continue
changing the straightedge from side to side and
aligning the locator arrows until the image of the
Appendix
Figure A1 Setup for Locating Virtual Images
Figure A2 Locating a Virtual Image
Locator B
Locator A
50 mm Focal
Length Spherical
Mirror
f
f
d
i
d
o
0
cm
1
2
3
4
2
0
cm
1
2
3
4
Locator A
Locator B
0
cm
1
2
3
4
2
0
cm
1
2
3
4
Locator A
(c) (b) (a)
Straightedge Locator B