Lenses
Lenses have many applications ranging from simple light collection to precise imaging and image transfer. Lenses are classified as single lenses, cylindrical lenses and achromatic lenses according to the different applications.
LENSES
MATERIAL
ILLUSTRATION
PROPERTY
& APPLICATION
Plano-convex
BK7
Fused Silica
Sapphire CaF2
Sapphire CaF2
Positive
focal length. Most suitable where one conjugate is more than five times
over the other, e.g. in sensor application or for use with near collimated
light. Also where both conjugates are on the same side of the lens. e.g.
as in add-on lens to increase the numerical aperture.
Double-convex
BK7
Fused Silica
Most
suitable where the conjugates are on opposite sides of the lenses and
the ratio of the distances is less than 5:1, e.g, as simple image relay
components.
Plano-concave
BK7Fused
Silica
Sapphire CaF2
Sapphire CaF2
Negative
lens with the form most suitable where one conjugate is more than five
times the other, e.g. producing divergent light from a collimated input
beam.
Double-concave
BK7
Fused Silica
Negative
lens with the form most suited to producing diverging light or virtual
images, where the input light is converging.
Meniscus
Positive
BK7
These
lenses may be used to increase the numerical aperture of a positive lens
assembly without undue increase in the aberrations.
Meniscus
Negative
BK7
Fused Silica
Sapphire CaF2
Sapphire CaF2
The
best lens from where one conjugates is relatively far from the lens, or
where both conjugates are the same size as the lens.
Cylindrical
BK7
Fused Silica
Used
to provide focusing power in one section only. For illumination or detection
of light from line sources. Also use for anamorphic compression of beams
and images
Achromatic
Combinations
of
two Optical grade
glasses
two Optical grade
glasses
These
lenses have considerably reduced values of spherical aberration, and chromatic
aberration. Best used to replace single components where performance must
be improved.