# As shown in Fig. 5-7p, a positive lens with focal length (f) is placed in contact with

## Question:

As shown in Fig. 5-7p, a positive lens with focal length \(f\) is placed in contact with a pinhole screen in a Young's experiment. The lens and pinhole plane are at distance \(z_{1}\) from the source and the observation screen is at distance \(z_{2}\)

from the lens and pinhole screen. For quasimonochromatic light and paraxial conditions, the lens can be modeled by an amplitude transmittance factor \[ \mathbf{t}_{l}=\exp \left(-j \frac{\pi}{\lambda f} ho^{2}\right) \]

Assuming a spatially incoherent source, find the relationship between \(z_{1}, z_{2}\), and \(f\) that guarantees that the spatial phase of the fringe pattern observed depends only on the vector separation of the two pinholes and not on their absolute locations with respect to the optical axis.

## Step by Step Answer:

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