general T.O topics 2 Flashcards
(154 cards)
1
Q
states that in a homogeneous optical medium, light travels along a straight path
A
Law of Rectilinear Propagation of Light
2
Q
Proofs of Law of rectilinear propagation of light
A
- Shadow of an opaque object with a point source of light
- Shadow of an opaque object with an extended light source
- Pinhole camera
- Eclipses
3
Q
an object placed between a point source of light and screen will cast a shadow with a sharply defined boundary, the boundary line is the intersection of the screen with the conical surface that touches the surface of the obstacle and has its apex at the source
A
Shadow of an opaque object with a point source of light
4
Q
is the smallest possible source of light
A
Point source
5
Q
dark image formed by intercepting the light rays; formed if you block the rays of light
A
Shadow
6
Q
The region of complete shadow formed on the screen
A
UMBRA
7
Q
when an opaque disk is interposed between an extended light source and a screen, part of the screen is illuminated by one extremity of the source, another part is illumination by the other extremity, the shadow of the sphere will not be clearly define
A
Shadow of an opaque object with an extended light source
8
Q
the region of partial shadow, which receives light from only a portion of the source
A
Penumbra
9
Q
- where an inverted real image is formed
- the size of the image depends on the length of the camera and the distance of the object from it
A
Pinhole Camera
10
Q
the natural phenomenon that illustrates the formation of shadows
A
Eclipses
11
Q
the visual angle formed at the nodal point of the eye by the object
A
Apparent Height or Angular height
12
Q
2 apparent height factors:
A
- the distance of the object from the observer
- the size of the object
13
Q
science of measuring and comparing light quantities
A
Photometry
14
Q
instrument used for measuring and comparing light quantities
A
Photometer
15
Q
3 aspects of Photometry
A
- the Luminous flux or flow of light from the source
- the luminous intensity of the source
- the illuminance or brightness of a surface
16
Q
- rate of flow of luminous energy from a source
- radiant energy which is emitted by a source per unit time which causes the sensation of sight
A
Luminous Flux
17
Q
unit if luminous flux
A
Lumen
18
Q
- quantity of light emitted by a source in one given direction
A
Luminous Intensity
19
Q
the unit of luminous intensity
A
candle or candle power
20
Q
- measure of the illumination
- brightness of the surface
A
Illuminance
21
Q
states that the illumination of a surface placed perpendicularly to he direction in which the light is traveling varies inversely as the distance of the surface from the source
A
Inverse square law
22
Q
states that the illumination of a surface varies as the cosine of the angle of incidence
A
Cosine Law of illumination
23
Q
states that the candle powers of two light sources are directly proportioned to the squares of their distances from the screen of a photometer.
A
Law of intensity
24
Q
for an extended light source, like fluorescent lamps, the illumination decreases as the inverse first power of the distance
A
Luminance of Extended Sources
25
Law that states the angles which the incident and reflected rays make, respectively with the normal reflecting surface, are equal
Laws of Reflection
26
2 Types of reflection:
1. Specular (regular) reflection
2. Diffuse (irregular) reflection
27
* reflection that occurs only on smooth surfaces such as glass, mirror, mercury where most of the energy is reflected
* reflected rays travel in the same direction
Specular (regular) Reflection
28
* reflection that occurs on rough and uneven surface like wood where most of the energy is absorbed
* reflected rays spread out in different directions
Diffuse (irregular) Reflection
28
* reflection that occurs on rough and uneven surface like wood where most of the energy is absorbed
* reflected rays spread out in different directions
Diffuse (irregular) Reflection
29
Portion of a sphere which was sliced away and then silvered on one of the sides to form a reflecting surface
Spherical Mirrors
30
silvered on the inside of the sphere
the curve is away from the observer
Concave mirrors
31
* silvered on the outside of the sphere
* the reflecting surface is curved towards the observer
Convex mirrors
32
Line passing through the center of the sphere and attaching to the mirror in the exact center of mirror
PRINCIPAL AXIS
33
the point in the center of sphere from which the mirror was sliced
Center of Curvature
34
the point on the mirror's surface where the principal axis meets the mirror
Vertex
35
midway between the vertex and the center of curvature
Focal point
36
distance from the vertex to the center of curvate
Radius of Curvature
37
distance from the mirror to the focal point
Focal Length
38
usable rays in construction of images: Ray#1 ?
Ray #1 - ray parallel to principal axis passes through F after reflection
39
usable rays in construction of images: Ray#2 ?
Ray #2 - ray passing through F will be reflected parallel to the principal axis
40
usable rays in construction of images: Ray #3 ?
Ray #3 - ray passing through C will follow the same path back after reflection
41
usable rays in construction of images: Ray #4 ?
Ray #4 - ray incident to the vertex of the mirror will be reflected according to the laws of reflection
42
images produced by CONCAVE MIRRORS: Case #1 ?
Case 1 - ***Object at an infinite distance from the mirror***
A point image is formed at the PRINCIPAL FOCUS
43
images produced by CONCAVE MIRRORS: Case #2 ?
Case 2 - ***Object at a finite distance beyond the center of curvature***
image is REAL, INVERTED, and MINIFIED, located between the CENTER OF CURVATURE and the PRINCIPAL FOCUS
44
images produced by CONCAVE MIRRORS: Case #3 ?
Case 3 - ***Object at the center of curvature***
image is REAL, INVERTED, and has the SAME SIZE OF THE OBJECT located at the CENTER OF CURVATURE
45
images produced by CONCAVE MIRRORS: Case #4 ?
Case 4 - ***object between the center of curvature and the principal focus***
image is REAL, INVERTED, and MAGNIFIED located beyond the CENTER OF CURVATURE
46
images produced by CONCAVE MIRRORS: Case #5 ?
Case 5 - ***Object at the principal focus***
NO IMAGE FORMED
47
images produced by CONCAVE MIRRORS: Case #6 ?
Case 6 - ***object between principal focus and mirror***
image is VIRTUAL, ERECT and MAGNIFIED, located BEHIND THE MIRROR
48
images formed by CONVEX MIRROR:
always ***VIRTUAL, ERECT***, and ***MINIFIED***
image is ***BEHIND THE MIRROR*** within its ***PRINCIPAL FOCUS***
49
image formed in PLANE MIRROR:
***VIRTUAL, ERECT, SAME SIZE***
***SAME DISTANCE*** as the object from the mirror
50
image formed in PLANE MIRROR:
***VIRTUAL, ERECT, SAME SIZE***
***SAME DISTANCE*** as the object from the mirror
51
refers **to the ratio of image length to object length measured in planes that are perpendicular to the optical axis**
Linear magnification
52
bending of light as it goes from one medium to another of different density
Refraction
53
Laws of refraction:
A ray of light striking a refracting surface perpendicularly is \_\_\_\_\_
Undeviated
54
Laws of refraction:
A ray of light which passes obliquely from a RARER to a DENSER medium is bent ______ the normal.
TOWARDS (decrease speed)
55
Laws of refraction:
A ray of light which passes obliquely from a DENSER to a RARER medium is bent _____ from the normal.
AWAY (increase speed)
56
Laws of refraction:
the incident ray, normal and refracted ray, all lie in the \_\_\_\_\_\_\_.
***Same plane*** at the ***point of reference***
57
Laws of refraction:
law in which Sine of the angle of incidence is to the sine of the angle of refraction as the inverse ratio of their indices
Snell's Law
58
ratio of the speed of light in ***empty space or vacuum*** (air) to the speed of light in some other optical medium
Absolute index of refraction
59
ratio of the speed of light of ***two optical media***, of which neither is air or when such is the case that light does not originate from air
Relative index of refraction
60
refractive index of air:
1.0
61
refractive index of water:
1.33
62
refractive index of ethyl alcohol:
1.36
63
refractive index of crown glass:
1.523
64
refractive index of Polycarbonate:
1.58
65
refractive index of Diamond:
2.417
66
an optical medium having two refractive sides, both of which are plane and parallel
Plane refractors
67
Light passing through a plane refractor suffers no \_\_\_\_\_, and
merely a \_\_\_\_\_\_.
**permanent deviation**, *displacement*
68
the displacement suffered by the ray is dependent upon:
1. the **angle of incidence**
2. **thickness** of **plane refractor**
3. **indices** of **refraction**
69
an angle of incidence at which the angle of refraction makes an angle of 90 degrees with the normal angle of incidence, which just transmit a ray of light in a dense medium to pass out into a rare medium
Critical Angle
70
when the incident ray coming from a dense medium subtends an angle with the normal to the refracting surface, greater than the critical angle for the substance, it does not pass out into the rare medium but suffers \_\_\_\_\_.?
TOTAL INTERNAL REFLECTION
71
defined as a portion of a transparent substance bounded by two polished surfaces, both of which may be curved, or only one may be curved and the other plane.
LENS
72
grounded using a minus tool
spherical PLUS curvature
73
grounded using a plus tool
spherical MINUS curvature
74
wedge shaped portion of a refracting medium contained between two plane polished surfaces which are not parrellel to each other
PRISM
75
a ray of light passing through a prism is bent towards the \_\_\_\_\_
BASE
76
* It forms a magnified image of an object held within its focus
* when moved, an object viewed through it appears to move in opposite direction
CONVEX LENS
77
* it diminishes the apparent size of an object seen through it
* when moved, an object viewed through it appears to move in opposite direction
CONCAVE LENS
78
standard forms of Plus and Minus Lenses:
* ***_Plano convex/Plano concave_***
* ***_Bi convex- Bi concave_***
* ***_Equi-convex/Equi-concave_***
* ***_Plus/minus Meniscus_***
* ***_Periscopic Lenses_***
79
the back surface is plane, all the power being provided by the front surface:
Plano convex/Plano concave
80
both surfaces having same curve but of different power
Bi convex/Bi concave
81
both surfaces having the same curvature and power
Equi-convex/Equi-convave
82
the front is convex, the back surface is concave
Plus/minus meniscus lens
83
this lens is the form in which mass-produced lenses are now made
Plus/minus meniscus lens
84
all the plus lenses have back surface power of -1.25 D and all minus lenses have a front surface curve of +1.25 D
Periscopic lens
85
the line joining the center of curvature of the two sphere or lens
OPTIC AXIS
86
point through which rays of light pass unrefracted
OPTIC CENTER
87
line drawn perpendicular to the optic axis passing through the optic center, from which the object and image distances may be measured
Principal of Bending plane
88
images produced by ***convex*** lenses:
1. Object at an infinite distance from the mirror
a REAL IMAGE is produced at the FOCUS
89
images produced by ***convex*** lenses:
2. object is placed at a distance greater than twice the focal length
image is
* REAL,
* INVERTED,
* DIMINISHED
90
images produced by ***convex*** lenses:
3. object at a distance twice the focal length
* REAL IMAGE,
* INVERTED,
* SAME SIZE AS THE OBJECT
91
images produced by ***convex*** lenses:
4. object at a distance between 2f and f
* REAL IMAGE
* INVERTED
* MAGNIFIED
92
images produced by ***convex*** lenses:
5. object at the principal focus
NO IMAGE FORMED
93
images produced by ***convex*** lenses:
6. object between the principal focus and the lens
VIRTUAL IMAGE
ERECT
MAGNIFIED
94
image produced in ***concave*** lens:
ALWAYS VIRTUAL, ERECT AND DIMINISHED
95
This relation holds for any case of image formation by a convex or concave lens
Thin lens Equation and Linear magnification
96
The power of a ***surface lens*** depend upon its _____ and \_\_\_\_\_\_.
RADIUS OF CURVATURE and INDEX OF REFRACTION
97
have ***two different curves on a single refracting surface*** on or within the ***eye***
ASTIGMATISM
98
General classes of cylinder lenses:
1. ***Simple*** cyl
2. ***Compound*** cyl
3. ***mixed*** cyl
4. ***Cross***-cyl
99
cyl with no spherical equivalent
Simple cyl
100
cyl having plus or minus power in both meridians
(cyl
Compound cyl
101
cyl having plus power in one meridian and minus power in the other
(cyl \>sph)
Mixed cylinder
102
cyl having two similar or dissimilar cyl crossed at right angle
Cross-Cylinder
103
it is defined as changing the form of a lens prescription without changing its ***value***
Transposition
104
types of transposition:
1. Flat transposition
2. Toric Transposition
105
applicable to cylinder prescriptions, and by of any cylinder prescriptions may be changed to plus cylinders, minus cylinder or cross cylinder
FLAT TRANSPOSITION
106
process of finding the power or strength of the refracting elements which make up an ***unknown lens***
NEUTRALIZATION
107
Purpose of transposition:
1. to simplify the expression of a lens formula
2. to aid in changing or combining lenses in a trial frame
3. to facilitate the use of lenses to be used
108
Methods of neutralization:
1. By measurement of the focal length of lens
2. By determining the curvature of each of the surfaces of the lens
3. By computing the thickness difference between the center and edge of the lens
4. Hand neutralization
5. By the use of vertex power instrument
109
used for determining the curvature of each of the surfaces of the lens
LENS MEASURE
110
used for computing the thickness difference between the center and edge of the lens
CALIPER
111
used for hand neutralization of the lens
TRIAL LENSES
112
used for the use of vertex power instrument
LENSMETER/LENSOMETER
113
is measured from the lens to the image or focal plane with the source of light originating from infinity
FOCAL LENGTH
114
other term for lens measure
* Geneva lens measure
* Lens clock
115
other term for Lensmeter:
* Focimeter
* Vertometer
116
Types of mires:
* Circle of Dots (sphere lens)
* 2 sets of lines perpendicular to each other (cylinder lens)
117
* consist of two straight lines drawn at right angles to each other and representing the principal meridians of a lens or lens combinations.
OPTICAL CROSS
118
- describes the manner in which the lens is made
- depends on the use of definite base curve and all the other curves of the lens being determined by using the selected base curve as a point of reference
TORIC TRANSPOSITION
119
* – curvature upon which a series of power is ground
- power from which the other powers of the lens surface may be calculated
BASE CURVE
120
* Lens in which base curve is always the lowest [powered curve on the front surface
SV LENS
121
* base curve is always a sphere
- Lens in which The base curve is always on the same surface as the segment
BIFOCAL LENS
122
* The base curve on the segment side must be spherical in nature
* The cylinder element in bifocals is always ground on the surface opposite the segment side
FUSED BIFOCAL TORIC TRANSPOSITION
123
The deviation produced by a prism is expressed in terms of its?
PRISMATIC POWER
124
* Causing deviation of light without changing its vergence.
PRISM
125
Prisms do not affect the vergence because their surfaces are \_\_\_\_, the surface have \_\_\_\_\_.
FLAT, NO DIOPTRIC POWER
126
prism has converging surfaces which meet in a line called \_\_\_\_\_?
APEX
127
the prism's divergent extremities are connected by a surface called the \_\_\_\_\_?
BASE
128
Ray of light passing through a prism are bent toward the \_\_\_\_\_?`
BASE
129
An object observed through a prism is displaced apparently toward the \_\_\_\_\_?
APEX
130
An eye looking through a prism is turned towards the \_\_\_\_\_?
APEX
131
A prism that deviates a light ray 1.00 cm at a distance of 1 m is said to have a power of \_\_\_\_\_?
1 prism diopter
132
* Are used to alleviate symptoms associated with disorders of binocular vision by deviating light to fall on the foveas of both eyes. But it does not solve the underlying problems.
PRISM IN SPECTACLES
133
prisms Cause reduction in visual acuity due to
chromatic abberation
134
is created when the patient looks away from the optical center of any plus or minus lens
PRISMATIC EFFECT
135
THE PRISMATIC POWER ______ AS THE DISTANCE FROM THE OPTICAL CENTER OF THE LENS AND OR THE LENS POWER \_\_\_\_\_\_\_.
increases, increases
136
The greater the prism power, the more the image is \_\_\_\_\_?
displaced
137
There is no prismatic power along the _____ of the lens. ( a ray of light travels along the ______ is not deviated)
OPTICAL AXIS
138
A LENS has both ____ power and _____ power
DIOPTRIC AND PRISM
139
\_\_\_\_\_ power due to the curvature of the lens surfaces is manifest as a change in the vergence of light rays.
DIOPTRIC POWER
140
\_\_\_\_\_ power is manifest as a displacement of the image toward the apex of the prism.
PRISMATIC POWER
141
a result of inappropriate positioning of the optical centers,
UNWANTED prismatic effect
142
Prismatic effect can be computed using:
PRENTICE RULE
143
\_\_\_\_\_ is the distance from the center of the lens to the point in question.
displacement
144
A cylinder decentered ***along its axis*** will give _____ effect.
NO prismatic effect
145
A cylinder decentered ***perpendicular to its axis*** will give a _____ equivalent to a sphere of the same power.
prismatic effect
146
Incorporating a Prism in Prescription are achieved by:
* ACTUAL GRINDING
* DECENTRATION OF LENS
146
Incorporating a Prism in Prescription are achieved by:
* ACTUAL GRINDING
* DECENTRATION OF LENS
147
**If prisms are combined with their base-apex line parallel, and with their bases in the same direction, then their effects are considered to be additive or called \_\_\_\_?**
THIN PRISM COMBINATIONS
148
**If the two prism to be combined are** **NOT PARALLEL****, then the single effective prism can be produced by \_\_\_\_\_\_.**
resolving the two prisms
149
**A circle viewed through a prism appears slightly oval and with the upper and lower edges faintly blurred. The blurring occurs along the base-apex line; distinct along the axis.**
Prism aberration
150
**optical effect that occurs when an object viewed through a prism appears displaced toward the apex.**
**Produce an Optical Illusion**
151
**rotating a prism on its base-apex line or axis as the observer looks through it at an object causes the object to be distorted and the distortion is spoken of as \_\_\_\_\_\_?**
Metamorphopsia
152
**when a beam of solar light is made to pass through a prism of rock crystal or flint glass is broken up into its constituent parts.**
Dispersion of Light
