Question

Group 7

3. Consider the experimental set-up shown in Figure 4. A collimated laser beam of diameter hi-3mm is incident on a beam expansion lens set-up in which the focal point of both the lenses overlap. A collimated beam is one where light rays are parallel to each other and the beam does not diverge/converge. The first lens focuses the laser beam at its focal point, fi 30mm. Since the focal point of the second lens fa is at the same location, a collimated beam is formed on its other side as shown. Iff>fi, the diameter of the beam hz will be greater than h. The experiment is governed by the following equation where, M is called the magnification and f depends on your group number as given below: Groups 1 and 2:f: -60 mm Groups 3 and 4: f:-100 mm Groups 5 and 6:f - 125 mm Group 7:f-150 mm 1. What is the distance between the two lenses (L) in Figure 4[1 Point] 2. Calculate hz.[1 Point]

Answer 1

f2=150 for Group 7

1.)

L=f₁+f₂ = 30mm + 150mm

= 180mm

2.)

$\frac{f_{2}}{f_{1}}=\frac{h_{2}}{h_{1}}$

or h₂=(f₂/f₁)h₁

h₂=(150/30) x 3 mm

h₂=5 x 3 mm =15mm