State the surface powers required to produce the following lenses with +6.25D front curves.
a. -0.50 DS
b. +0.50 DS
c. +1.75 DS
Is a -6.75DS?....
To determine the required surface powers to produce these lenses with +6.25D front curves, you need to understand the calculation involved. The surface power of a lens is the reciprocal of its focal length, expressed in diopters (D). The formula to calculate the surface power is as follows:
Surface Power (D) = 1 / Focal Length (m)
First, let's calculate the focal length for the given +6.25D front curve:
Focal Length (m) = 1 / Front Curve (D)
Focal Length (m) = 1 / 6.25
Focal Length (m) = 0.16 meters
Now that we have the focal length, we can determine the required surface powers for the given lens prescriptions.
a. -0.50 DS:
To find the surface power required for a -0.50 DS lens, we need to subtract the lens prescription from the focal length:
Surface Power (D) = Focal Length (D) - Lens Prescription (D)
Surface Power (D) = 6.25 - (-0.50)
Surface Power (D) = 6.75 D
Therefore, the answer for a -0.50 DS lens is 6.75D.
b. +0.50 DS:
Similarly, for a +0.50 DS lens:
Surface Power (D) = Focal Length (D) - Lens Prescription (D)
Surface Power (D) = 6.25 - (+0.50)
Surface Power (D) = 5.75 D
Therefore, the answer for a +0.50 DS lens is 5.75D.
c. +1.75 DS:
For a +1.75 DS lens:
Surface Power (D) = Focal Length (D) - Lens Prescription (D)
Surface Power (D) = 6.25 - (+1.75)
Surface Power (D) = 4.50 D
Therefore, the answer for a +1.75 DS lens is 4.50D.
Regarding your question about -6.75DS, it is not mentioned in the original list of lenses. If you want to find the required surface power for a -6.75DS lens, you will need to follow the same process:
Surface Power (D) = Focal Length (D) - Lens Prescription (D)
Surface Power (D) = 6.25 - (-6.75)
Surface Power (D) = 13 D
Therefore, the answer for a -6.75DS lens would be 13D.