# Spherical lenses - PowerPoint PPT Presentation

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Spherical lenses. Spherical lenses. Spherical lenses. Thin , converging lenses: The rules. Section of a spherical surface with large radius of curvature R 2. Section of a spherical surface with large radius of curvature R 1. Thin, converging lenses. Thin, converging lenses.

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Spherical lenses

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#### Presentation Transcript

Spherical lenses

Spherical lenses

Spherical lenses

Thin, converging lenses: The rules

Section of a spherical surface with large radius of curvature R2

Section of a spherical surface with large radius of curvature R1

Thin, converging lenses

Thin, converging lenses

Thin, converging lenses

A) Any incoming ray parallel to the lens's axis always goes through the focal point on the other side!

Thin, converging lenses

Example: light a fire.

DEMO?

Thin, converging lenses

Thin, converging lenses

B) Any ray coming in through the lens's focal point always goes out parallel to the lens’s axis.

Thin, converging lenses

Example: making a spotlight.

Thin, converging lenses

Thin, converging lenses

C) Any ray aimed at the lens's center always goes through un-deflected!

Thin, converging lenses: IMAGING

Thin, converging lenses: IMAGING

Thin, converging lenses: IMAGING

Thin, converging lenses: IMAGING

Thin, converging lenses: IMAGING

Thin, converging lenses: IMAGING

Our previous convention

Example: An 0.5 m tall object stands 1.75 m in front of a converging lens (focal length 0.75 m). Where’s the image, and how big?

Like the concave mirror, you get different behavior if the object is closer than f to the lens:

Virtual, upright image on same side as object

Like the concave mirror, you get different behavior if the object is closer than f to the lens:

Virtual, upright image on same side as object

Like the concave mirror, you get different behavior if the object is closer than f to the lens:

Virtual, upright image on same side as object

Like the concave mirror, you get different behavior if the object is closer than f to the lens:

Virtual, upright image on same side as object

Like the concave mirror, you get different behavior if the object is closer than f to the lens:

Virtual, upright image on same side as object

Thin, converging lens

Example: An 0.05 m tall object stands .15 m in front of a converging lens (focal length 0.75 m). Where’s the image, and how big?

SIM

A Simple Camera: fixed focal length

Shutter

exposure

film

Aperture:

Exposure

Depth of field

A Simple Camera: fixed focal length

A Simple Camera: fixed focal length

A Real Camera

Thin, diverging lenses

Thin, diverging lenses

Thin, diverging lenses

A) A ray coming in parallel to the lens's axis always goes out at an angle as if it where coming from the focal point on the incident side!

Thin, diverging lenses

Thin, diverging lenses

B) A ray aimed at the lens's center always goes through un-deflected!

Thin, diverging lenses: IMAGING

Thin, diverging lenses: IMAGING

Thin, diverging lenses: IMAGING

Thin, diverging lenses: IMAGING

Thin, diverging lenses: IMAGING

Thin, diverging lenses: IMAGING

Image on same side as object

Image is upright

Virtual now

Fix it upto be the same formula as for the converging lens by making image and focal length negative!

Thin, diverging lenses: IMAGING

Example: An 0.5 m tall object stands 1.75 m in front of a diverging lens (focal length -0.75 m). Where’s the image, and how big?

THIN LENS EQUATIONS:

converging

diverging

Backwards from convention for mirrors

Example: Compare virtual images from converging and diverging lenses

2 m

O

O

I

I

5 m

2 m

5 m