Collectively, the nodal points, focal points, and principal points are called the cardinal points, because these 3 pairs of points completely describe the first-order properties of an optical system. Notice that 2 pairs of cardinal points are conjugate. The posterior principal point is the image of the anterior principal point, and the same relationship holds for the nodal points. The focal points, however, are not conjugate. Two pairs of cardinal points are associated with planes: the focal points and the principal points, but there is no such thing as a nodal plane associated with a nodal point.
Section Exercises
1.1.An object is 25 cm to the left of point P for a +9.00 D lens. Where is the image? Show Answer
1.2.An object is 1 m to the left of point P for a +9.00 D lens. Where is the image? Show Answer
1.3.An object is 20 cm to the left of point P for a +9.00 D lens. Where is the image? Show Answer
1.4.An object is 50 cm to the left of point P for a +5.00 D lens. Where is the image? Show Answer
1.5.An object is 25 cm to the left of point P for a +5.00 D lens. Where is the image? Show Answer
1.6.Suppose the object is 1.00 m to the right of point P, and the lens has a power of +4.00 D (Fig 1- 35). Where is the image?
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1.7.A (virtual) object is 50 cm to the right of P for a +2.00 D lens. Where is the image? Show Answer
1.8.A (virtual) object is 1 m to the right of P for a +1.00 D lens. Where is the image? Show Answer
1.9.A (virtual) object is 40 cm to the right of P for a +2.50 D lens. Where is the image? Show Answer
1.10.Locate the image of an object 1 m to the left of P for a –4.00 D lens.
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1.11. Suppose an object is 50 cm to the left of a +10.00 D lens. A +9.00 D lens is 32.5 cm to the right of the first lens (Fig 1-36). Where is the image?
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1.12. An object in air is 50 cm to the left of P and the lens power is +6.00 D. On the other side of the lens is water (n = 1.33). Where is the image?
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Figure 1-35 In this case, the object is to the right of point P. Since by convention light moves from left to right, how does
light from the object reach the lens? (Illustration developed b y Edmond H. Thall, MD.)
Figure 1-36 Example of imaging using 2 lenses. (Illustration developed b y Edmond H. Thall, MD.)