optics 2

How does the apex angle affect the deviation of light in a prism?

Larger apex angles increase deviation

How does the index of refraction of a prism material affect the deviation of light?

Higher index increases deviation

What is the relationship between deviation angle (d) and prism power (P)?

The deviation angle in degrees is directly proportional to the number of prism diopters of a prism

If a prism has an apex angle of 4° and deviation of 2°

what is the index of refraction?

What type of mirror converges light?

Concave mirror

What type of mirror diverges light?

Convex mirror

How does a plane mirror affect the image formed?

Virtual and erect and same size

What is the formula for focal length (f) of a spherical mirror?

f = R/2

What is the relationship between object distance (l)

image distance (l')

Image formed by concave mirror when object is beyond focal point?

Real and inverted

Image formed by convex mirror?

Virtual and erect

What is the magnification formula for mirrors?

M = L'/L

Where is the image if object is 10 cm in front of a concave mirror with f = 5 cm?

10 cm in front of the mirror

Magnification of convex mirror if l = 20 cm and l' = -10 cm?

-0.5

Primary function of a thin lens?

To refract light and form images

Formula relating secondary focal length (f') and power (F)?

F = 1/f'

Effect of convex lens on parallel rays?

Converges them

Effect of concave lens on parallel rays?

Diverges them

Thin lens equation?

1/u + 1/v = 1/f

Do thin lenses exist? Why study them?

No; they are a useful model that gives approximate solutions

Where is the image if object is 40 cm in front of convex lens with f' = 20 cm?

20 cm behind the lens

Image formed by convex lens when object is inside focal length?

Virtual and erect

Image formed by concave lens?

Virtual and erect

Magnification of convex thin lens if l = 20 cm and l' = 40 cm?

2

What is a thick lens?

A lens with significant thickness

How does thickness of a lens affect optical power?

It affects the vergence calculation

What is radius of curvature?

Distance from center of curvature to lens surface

What is the optical axis?

Imaginary line through centers of curvature

Front vertex focal length?

Distance from front surface to primary focal point

Back vertex focal length?

Distance from back surface to secondary focal point

Equivalent power formula for thick lens?

F = F1 + F2 - (t/n) F1 F2

Effect of increasing thickness of biconvex lens?

Decreases equivalent power

Can thick lenses be studied as succession of refractions?

Yes

Effect of thicker lens on image formation?

Affects both magnification and image distance

Equivalent power if F1 = +5D

F2 = -2D

Effect of increasing curvature on power?

Increases power

Difference between thick and thin lens calculations?

Thick lens requires accounting for thickness

Relationship between lens thickness and power?

No clearly defined relationship

Effect of negative meniscus lens?

Diverges light

Effect of positive meniscus lens?

Converges light

Significance of center of curvature?

Point from which radius is measured

Formula for equivalent power of thick lens?

Fe = F1 + F2 - (n/t) F1 F2

Nominal power if n = 1.5

R1 = +10 cm

In a mirror

what is n'?

Effect of thickness on optical center?

Causes a shift

Role of transformation equations?

Account for surface separation

Back vertex power formula?

BVP = F1 + F2/(1 − (n/t)F1F2)

Effect of biconvex lens on light?

Converges light

Effect of biconcave lens on light?

Diverges light

Image from thick convex lens with object beyond f?

Real and inverted

Image from thick concave lens?

Virtual and erect

Image location for object 20 cm before biconvex thick lens?

10 cm behind the lens

Index effect on focal length?

Higher index decreases focal length

Shape of positive meniscus lens?

One concave and one convex surface

Equivalent power formula?

Fe = F1 + F2 - (d/n) F1 F2

Final vergence if object = -25 cm

F1=+4D

Radius of curvature effect on power?

Smaller radius increases power

Significance of principal planes?

They simplify system analysis

Thin lens: object and image distances equal/opposite?

Magnification = -1

Biconvex vs biconcave thick lens image formation?

Biconvex → real image; biconcave → virtual image

Role of center of curvature?

Helps calculate radius of curvature

Image for polycarbonate lens F1=+2D

F2=+10D

Effect of lens shape?

Affects focal length and image position

How does separation between surfaces affect optical properties?

Affects both power and image distance

What is the primary purpose of a sphero-cylinder lens?

To correct astigmatism

How does a sphero-cylinder lens differ from a spherical lens?

It combines spherical and cylindrical surfaces

What is the cylinder axis in a sphero-cylinder lens?

The meridian with zero refractive power

When constructing a power cross from a sphero-cylindrical prescription…

All answers are correct

What is the principal meridian in a sphero-cylinder lens?

The meridian with maximum power

What is the spherical equivalent of +2.00 sphere and -1.00 cylinder?

+1.50 D

What type of lens corrects myopic astigmatism?

Minus sphero-cylinder lens

Formula for power in 180° meridian when axis is x180°?

Sphere power + Cylinder power

What does the axis of a cylindrical lens determine?

The direction of no power

How does a cylindrical lens affect light in the direction of its axis?

Does not affect it

What is the optical center of a sphero-cylinder lens?

The point where light passes undeviated

Total power at the axis meridian for +3.00 sphere / -2.00 cyl @ 90°?

+3.00 D

Effect of a cylindrical lens on parallel rays?

Focuses them into a line

How is cylinder power specified in a prescription?

Along with the axis orientation

Purpose of cross-cylinder lenses?

To refine astigmatic corrections

How does a sphero-cylinder lens correct astigmatism?

By compensating for unequal curvatures in the eye