Question

The two lenses of an achromatic doublet should have

• A. equal powers
• B. equal dispersive powers
• C. equal ratio of their power and dispersive power
• D. sum of the product of their powers and dispersive power equal to zero

Answer 1

Answer: (D)

The two lenses of an achromatic doublet should have, sum of the product of their powers and dispersive power $=$ zero.