工程光学英语补充内容和习题

The focal ray passes through F and then is rendered parallel to the axis.
The chief ray goes through the principal point without deviation.
14
Some Keywords and concept
1
2. Law of Rectilinear propagation
Light as it advances through free space or through homogeneous, isotropic matter follows a beeline. (a direct straight course). Example: Shadows
12
Homework ( P18-Example)
13
Some Keywords and concept
1. Graphical construction
Parallel ray Chief ray
ቤተ መጻሕፍቲ ባይዱ
F
H
H’
F’
Focal ray
The parallel ray is first parallel to the axis and then, after refraction passes through F’.
2
3. The Law of Reflection
A light ray striking a reflecting surface and reflected from it makes equal angles with the normal to the surface at the point of incidence,
English Summary
1. The electromagnetic spectrum
short
long
Wave length
Gamma X- Ultra V Infra- Micro Radio Rays Rays violet red -waves -waves
380nm 780nm
violet-blue deep-red
2. Newton’s lens equation (x, x' are called Newton’s extrafocal object and image distances, respectively )
3. Gauss’ equation
15
Homework
1. An object 1cm high is 30cm in front of a thin lens with a focal length of 10cm. Where is the image? Verify your answer by graphical construction of the image.
upright or inverted, real or virtual) 8. Concave and convex mirror
8
Some Concept
1. Vertex is the point where the optic axis intersects the surface.
2. Object distance is the distance from vertex to the object.
3. Image distance is the distance from vertex to the image.
4. Center of curvature is the center of single spherical surface.
5. Meridional plane is a plane containing the optic axis and the object.
nsinI=n'sinI' The incident ray, the refracted ray, and the surface normal are all coplanar.
4
5. Total Internal Reflection
Incident ray
normal
Denser medium
2. Principal points are the points where the optical axis intersects principal planes.
3. Focal points (the first~, the second ~ / the object-side ~, the image-side ~)
11
4. focal length is the distance from the principal point to the focal point.
5. A on-axial point object at infinity and the second focal point are conjugate.
2. Light from a water medium with n=1.33 is incident upon a water-glass interface at an angle of 45o . The glass index is 1.50. What angle does the light make with the normal in the glass?
Surface Critical angle
Refracted ray Rarer medium
6. Fermat’ principle
Light takes the path that requires the least time.
5
7. Key words and concept
Image space extends from infinity on one side to infinity on the other. The same holds for the object space; both completely overlap. Whether a given point is in the object space or the image space depends on whether it is part of a ray before or after refraction. If a given point is in the object space, it is a point object, otherwise it is a point image.
P12 4&9
7
Some Keywords
1. single spherical surface
2. converge and divergence 3. conjugate (~ points, ~ planes, ~ distance etc) 4. magnification
(transverse ~, axial ~, angular ~) 5. Lagrange’s invariant 6. sign convention (vertex, image distance, ) 7. image characteristics (larger or smaller,
9
Homework
1. A goldfish swims 10cm from the side of a spherical bowl of water of radius 20cm. Where does the fish appear to be? Does it appear larger or smaller?
1. Magnification
Transverse magnification (Lateral magnification) is defined as the ratio of image size, y', to object size, y.
Axial magnification (longitudinal magnification) is defined as the ratio of a short length, or depth, in the image measured along the axis, to the conjugate length in the object. In the air, it is equal to the square of the transverse magnification.
The angle made by the incident ray, that made by the refracted ray, and the surface normal at the point of incidence in a refractive process obey the expression
Angular magnification (magnifying power) The total magnification of a combination of lenses is the product of
the magnification of the individual lenses.
17
Keywords and concept
2. Nodal points are where no refraction occurs. Whenever the refractive indices on either side of the lens are the same, the nodal points coincide with the principal points. If the refractive indices on the two sides of the lens are different, the N points would move away from the principal planes, toward the side of higher index.
P13-12&14
10
Some Keywords and concept
1. Principal planes are defined as the loci where refraction is assumed to occur without reference as to where it actually does occur.
I''=-I
and the incoming ray, the outgoing ray, and the normal to the surface at the point of intersection all lie in the same plane.
3
4. The Law of Refraction
6
Homework
1. In ancient times the rectilinear propagation of light was used to measure the height of objects by comparing the length of their shadows with the length of the shadow of an object of known length. A staff 2m long when held erect casts a shadow 3.4 m long, while a building’s shadow is 170 m long. How tall is the building?
2. A lens is known to have a focal length of 30cm in air. An object is placed 50cm to the left of the lens. Locate the image.
P36-1&3
16
Keywords and concept
2. An object is located 2cm to the left of convex end of a glass rod which has a radius of curvature of 1cm. The index of refraction of the glass is n=1.5. Find the image distance.