Simple and accurate method for determining lens focal length

José Sasián

doi:10.1117/1.OE.62.3.034108

Simple and accurate method for determining lens focal length

José Sasián

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

A simple and accurate method for determining the focal length of a lens is presented. There is no need to know the distance between lens principal planes and can be performed with easily available and inexpensive hardware. Depending on the test lens (TL) f-number, the error on determining focal length can be in the order of 0.1% of the focal length. We discuss determining focal length with the Newton equation f2 = zz ′ , with the Bessel equation f = ((L - PP)2 - D2) / 4 (L - PP), with equation f2 = y ′ (y + y ′ ), or with equation f = (y2 - PP2) / 4PP.

Original language	English (US)
Pages (from-to)	34108
Number of pages	1
Journal	Optical Engineering
Volume	62
Issue number	3
DOIs	https://doi.org/10.1117/1.OE.62.3.034108
State	Published - Mar 1 2023

Keywords

autocollimation
focal length
focus measurement
optical bench

ASJC Scopus subject areas

Atomic and Molecular Physics, and Optics
General Engineering

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10.1117/1.OE.62.3.034108

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title = "Simple and accurate method for determining lens focal length",

abstract = "A simple and accurate method for determining the focal length of a lens is presented. There is no need to know the distance between lens principal planes and can be performed with easily available and inexpensive hardware. Depending on the test lens (TL) f-number, the error on determining focal length can be in the order of 0.1% of the focal length. We discuss determining focal length with the Newton equation f2 = zz ′ , with the Bessel equation f = ((L - PP)2 - D2) / 4 (L - PP), with equation f2 = y ′ (y + y ′ ), or with equation f = (y2 - PP2) / 4PP.",

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AU - Sasián, José

PY - 2023/3/1

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N2 - A simple and accurate method for determining the focal length of a lens is presented. There is no need to know the distance between lens principal planes and can be performed with easily available and inexpensive hardware. Depending on the test lens (TL) f-number, the error on determining focal length can be in the order of 0.1% of the focal length. We discuss determining focal length with the Newton equation f2 = zz ′ , with the Bessel equation f = ((L - PP)2 - D2) / 4 (L - PP), with equation f2 = y ′ (y + y ′ ), or with equation f = (y2 - PP2) / 4PP.

AB - A simple and accurate method for determining the focal length of a lens is presented. There is no need to know the distance between lens principal planes and can be performed with easily available and inexpensive hardware. Depending on the test lens (TL) f-number, the error on determining focal length can be in the order of 0.1% of the focal length. We discuss determining focal length with the Newton equation f2 = zz ′ , with the Bessel equation f = ((L - PP)2 - D2) / 4 (L - PP), with equation f2 = y ′ (y + y ′ ), or with equation f = (y2 - PP2) / 4PP.

KW - autocollimation

KW - focal length

KW - focus measurement

KW - optical bench

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Simple and accurate method for determining lens focal length

Abstract

Keywords

ASJC Scopus subject areas

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