Figure 2-39. Letter F as reflected by optical elements

TM 9-258

(1) An image, regardless of size, that shows

mirror, it appears to be located at a distance behind the

the face of an object unchanged is said to be normal and

reflecting surface equal to the distance of the object from

erect (A, fig 2-39). When the object is seen as

the front of the mirror. The image is erect and reverted

horizontally transposed through 1800, it is termed

as are all single reflections from vertical plan mirrors.

b. In a dark room, the image of a tiny point of light

reverted and erect (B, fig 2-49). Reversion is the effect

seen in a vertical mirror where the image is reversed so

as viewed in the mirror appears to the observer to be

that the right side of the object becomes the left side of

located behind the mirror and on the other side of the

room where it actually is. The observer sees along the

(2) The image of an object with its face

path of the reflected ray to the point where the ir dent ray

unchanged but upside down in termed normal and

is reflected by the mirror. His line of sir :is extended in

inverted (C, fig 2-39). Inversion is the effect seen in a

his mind in a direct line through and beyond the mirror.

horizontal mirror where the image is inverted so that the

The apparent position of the point of light in the mirror is

top of the object becomes the bottom of the image. If it

located directly across the room from the light source

appears turned from left to right as well as upside down,

and at the same distance behind the mirror as the light

it is said to be reverted and inverted (D, 2-39). This is

source is in front of the mirror (EYE "A", fig 2-40).

the effect seen on the ground glass of a camera

2-20. Image Reflection by Plane Mirror.

a. When the image of an object is seen in a

2-27