GHOST IMAGES

Question 1

Cause of ghost images

Answer 1

Light incident on a lens will be reflected by one or both surfaces

Question 2

Catoptric Image

Answer 2

Formed through reflections

Question 3

Catadioptric image

Answer 3

Formed through reflection and refraction

Question 4

When are ghost images troublesome

Answer 4

When the vergence of the image is similar to the lens vergence

Question 5

Ghost image 1

Answer 5

• total internal reflection in front of lens
• most troublesome
• AR coating is only solution

Question 6

Ghost image 2

Answer 6

• reflection of cornea on back surface of lens
• high power negative lenses
• resolved with AR coating / BVD change

Question 7

Ghost image 3

Answer 7

• reflection of cornea on front surface of lens
• high powered plus lenses
• resolved by lens form, AR coating and BVD change

Question 8

Ghost image 4

Answer 8

• reflection sources behind lens on back surface
• common with tinted lenses/ larger aperture
• resolved with back surface AR coating/ smaller frame

Question 9

Ghost image 5

Answer 9

• reflection sources behind the lens on front surface
• common in tinted lenses/ larger aperture
• resolved with back surface AR costing/ smaller frame