Lensmeter

Lensmeter is a device used by optometrists and opticians to verify the correct prescription in a pair of eyeglasses. It is also known as a lensometer, focimeter, or vertometer.

Function

The lensmeter works on the principle of back vertex power, which measures the optical power of the lens. This is done by focusing light through the lens and measuring the focal point at which the light converges.

Components

The lensmeter consists of several components:

• Target Eyepiece: This is where the user looks through to see the target.
• Lens Table: This is where the eyeglasses are placed.
• Prism Compensator: This is used to measure the prism power of the lens.
• Power Drum: This is used to adjust the focus of the target.

Usage

To use a lensmeter, the eyeglasses are placed on the lens table and the target is viewed through the eyepiece. The power drum is then adjusted until the target comes into focus. The power of the lens can then be read off the power drum.

Types of Lensmeters

There are two main types of lensmeters:

• Manual Lensmeters: These require the user to manually adjust the focus of the target.
• Automatic Lensmeters: These automatically adjust the focus of the target.

See Also

• Optometry
• Optician
• Eyeglasses

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