KMK 7.4: Aberrations of Lenses and Corrective Lens Designs

Pataasin ang iyong marka sa homework at exams ngayon gamit ang Quizwiz!

What type of lens should you Rx to correct curvature of field?

-Percival form lenses (base curve is based on tscherning ellipse which gives a flatter base curve)

Distortion is determined by the location of the...?

-aperture stop

Minus lenses lead to what kind of distortion?

-barrel -most minus in the center

Both curvature of field and radial astigmatism can be corrected by...?

-choosing the correct base curve (primarily Oswalt) -choosing focal point lenses (fully correct the residual astigmatism)

What is curvature of field?

-intertwined with oblique/radial astigmatism -plane object forms a curved image with decreased image quality as the distance increases *hyperopes can accommodate to clear up the aberration

Longitudinal chromatic aberration is ____________ related to abbe value

-inversely

Coma occurs only for _______ axis point sources

-off axis *correct this with aspheric lenses (aspheric lenses modify the lens surface without changing the power)

Oblique/radial astigmatism is the result of...?

-on and off axis light coming through the lens

Spherical aberration is created by what type of points?

-on and off axis points -marginal rays bend more than paraaxial rays *use an aspheric lens to correct

What is used to correct for distortion?

-orthostatic doublet

Plus lenses lead to what kind of distortion?

-pincushion -more plus in the center

Lateral/transverse chromatic aberration is related to ____________

-prismatic effect

T/F shorter wavelengths bend more as they pass through an interface or optical system than do longer wavelengths

-true -all wavelengths are not focused at the same location so the image will vary in location (longitudinal chromatic aberration) and size (lateral chromatic aberration)

If you have a material with a low Abbe value what are 3 things you can do to minimize the effects of chromatic aberration?

-use shorter vertex distances -use monocular PDs -include sufficient pantoscopic tilt

What is the formula for longitudinal chromatic aberration?

CA=F/v(abbe number)


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