Question

In your initial discussion post, identify the pros and cons of using mirrors versus lenses in each of the following applications:

• a large, ground-based, astronomical telescope
• a small “spy” scope
• a terrestrial telescope designed only to read license plates

Answer 1

1. Telescope – monocular optical instrument possessing magnification for observing distant objects, especially in astronomy. Refracting telescopes – are telescopes that use lenses are and those that use concave parabolic mirrors are called reflecting telescopes.

Pros of MIRROR telescope

• They are easier to construct and not expensive to produce

• made larger and more durable (more light can be directed to the eyepiece which is good)

• cannot have any occlusions

• mirrors have less spherical aberration

• reflect all wavelengths of light equally

• more magnification power for cheaper version

Cons:

• it must also be realigned after cleaning, which can be expensive - maintenance disadvantage

• Reflective Surface Disadvantage

LENSES telescope

Pros:

• Easy to use

• More reliable

Cons of Lens telescope:

• are not easy to construct and expensive to produce

• May have occlusions

• spherical aberration are more

• Doesnt reflect wavelengths of light equally they bend light differently

• Less magnification power for cheaper version

• heavy

• Longer body

2. Pro of MIRROR periscope

• it helps us to see further than our view that is what is above us or sometimes even below us.

•Light weight

Cons:

• it may not work properly and show distorted images due to fog. ; Some have a narrow field of view ; May be detected by others Ungainly (long, takes up space),

•Not as rugged as prisms.

• Maintenance of reflection surface

Pros of Prism periscopes

• incorporated lenses for magnification and function as telescopes.

• They typically employ prisms and total internal reflection instead of mirrors, because prisms, which do not require coatings on the reflecting surface, are much more rugged than mirrors.

• May be fitted with additional optical capabilities such as range-finding and targeting.

Cons.

Mechanically disadvantage:

Complex optically ;

Some have a narrow field of view ;

May be detected by others

Ungainly (long, takes up space)

Heavy weight

3. MIRROR : Terrestrial telescope (Cassegrain)

Pro: Good for distant terrestrial viewing, greater magnification is attained also they are shorter.

Cons:  It is not what people expect a telescope to look like, slight light loss due to secondary mirror obstruction compared to refractors. Generally not suited for most terrestrial applications nor for to view objects in the sky.

LENS: Terrestrial telescope

Pro: An advantage is that it makes it possible to vary the magnification of the telescope.

Cons- This system has the disadvantage increasing the length of the telescope.