1. A multimode optical fiber for fiber-optic distributed temperature sensing (DTS), comprising:
a core part; and
a cladding part,
wherein the core part has a structure including a plurality of concentric layers in which a refractive index changes stepwise so as to be higher toward a central area, and a quantity of addition of fluorine to silica glass of the core part is adjusted so as to be entirely increased toward an outer layer,
wherein the number M of the layers of the core part is located within a range of 3\u2266M\u226620 and
wherein the refractive index of the entire core is greater than the refractive index of the cladding layer.
2. The multimode optical fiber according to claim 1, wherein in a refractive index profile of the core part, when the central part and an end part in a radial direction of the core part are allowed to satisfy a below-described expression (1) as an ideal refractive index profile, the refractive index of at least one layer except a central layer of the layers corresponds to the ideal refractive index profile of the expression (1):
n(r)=n1{1\u22122\u0394(ra)\u03b1}\xbd, 2.0\u2266\u03b1\u22662.1\u2003\u2003(1)
wherein n designates a refractive index difference, n1 designates a refractive index of the center of the core, \u0394 designates a relative refractive index difference, a designates a radius of the core, r designates a distance from the center of the core and a designates a coefficient of refractive index profile.
3. The multimode optical fiber according to claim 2, wherein the refractive index of all the layers of the core part correspond to the ideal refractive index profile of the expression (1).
4. The multimode optical fiber according to claim 1, wherein a numerical aperture NA is not lower than 0.18.
5. The multimode optical fiber according to claim 1, wherein a bandwidth is not lower than 200 MHz\xb7km.
6. The multimode optical fiber according to claim 1, wherein the increase of attenuation is not higher than 0.2 dBkm in a wavelength area of a range not lower than 800 nm and not higher than 1700 nm after the elapse of 300 hours in an atmosphere of hydrogen of 2 atm and under an environment of 150\xb0 C.
7. The multimode optical fiber according to claim 6, wherein a bandwidth is not lower than 200 MHz\xb7km.
8. The multimode optical fiber according to claim 6, wherein a numerical aperture NA is not lower than 0.18.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A wearable display system comprising:
at least one display panel to display a signal;
a waveguide to transmit the signal that is incident thereon from the display panel, the waveguide having first and second ends; and
at least one magnifying lens attached to one of the ends of the waveguide to magnify the signal transmitted via the waveguide,
wherein at least one of the ends of the waveguide is diagonally cut at a predetermined angle so that the signal displayed by the display panel is totally reflected inside the waveguide.
2. The system of claim 1, further comprising at least one reflection plate to reflect the signal displayed by the display panel to the diagonally cut end of the waveguide.
3. A binocular wearable display system comprising:
a plurality of display panels;
a waveguide to transmit a signal emitted from the display panels, the display panels being respectively positioned at first and second ends of the waveguide; and
a plurality of magnifying lenses attached to the waveguide to magnify the signal transmitted via the waveguide,
wherein the first and second ends of the waveguide are diagonally cut at a predetermined angle so that the signal emitted by the display panels is totally reflected in the waveguide.
4. The system of claim 3, further comprising a plurality of reflection plates respectively extending from the first and second ends of the waveguide to reflect the signal emitted by the display panels such that the emitted signal is transmitted into the waveguide through the first and second ends thereof.
5. A wearable display system comprising:
a display panel to display a signal;
a waveguide to transmit the signal incident thereon from the display panel, the waveguide having first and second ends; and
an optical device attached to a surface of the waveguide, the optical device to magnify the signal transmitted via the waveguide,
wherein the first and second ends of the waveguide are diagonally cut at first and second angles, respectively.
6. The system of claim 5, wherein the display panel is attached to the first end of the waveguide and the optical device is attached to the second end of the waveguide.
7. The system of claim 6, wherein the first angle is equal to an angle of total internal reflection of the signal transmitted via the waveguide.
8. The system of claim 7, wherein the second angle is the same as the first angle.
9. The system of claim 5, wherein the optical device is a reflection type optical device.
10. The system of claim 5, wherein the optical device is a transmission type optical device.
11. A wearable display system comprising:
a display panel to display a signal;
a waveguide to transmit the signal incident thereon from the display panel;
a prism attached to a first end of the waveguide, the prism to transmit the signal displayed by the display panel into the waveguide at an angle such that the transmitted signal undergoes total internal reflection inside the waveguide; and
an optical device to magnify the signal transmitted via the waveguide,
wherein a second end of the waveguide, opposite the first end, is cut at a predetermined angle.
12. The system of claim 11, wherein the optical device is a reflection type optical device.
13. The system of claim 11, wherein the optical device is a transmission type optical device.
14. The system of claim 11, wherein the predetermined angle is equal to the angle of total internal reflection.
15. A wearable display system comprising:
a display panel to display a signal;
a waveguide to transmit the signal incident thereon from the display panel; and
a prism attached to a first end of the waveguide to emit the signal transmitted via the waveguide,
wherein a second end of the waveguide, upon which the signal is incident from the display panel, is cut at a predetermined angle.
16. The system of claim 15, wherein the predetermined angle is equal to an angle of total internal reflection of the signal transmitted via the waveguide.
17. The system of claim 15, further comprising an optical device placed on the prism to magnify the signal emitted by the prism.
18. A wearable display system comprising:
a display panel to display a signal; and
a waveguide to receive the signal from the display panel and propagate the signal therein, the waveguide comprising an end to receive the signal and a side, an angle formed between the end and the side allowing total reflection of the signal within the waveguide.
19. The wearable display system according to claim 18, further comprising a lens to magnify the signal propagated through the waveguide.
20. The wearable display system according to claim 19, wherein the angle formed between the end and the side is the same as an angle of total reflection of the signal inside the waveguide.
21. The wearable display system according to claim 20, further comprising:
a frame to mount the waveguide;
a frame arm extending from the frame;
a light source mounted on the frame arm to emit the light; and
a reflection unit to reflect the emitted light to the waveguide.
22. The wearable display system according to claim 20, wherein the display system displays a virtual image of an object to a user.
23. The wearable display system according to claim 22, wherein a diameter D of the lens is calculated according to:
8
D
=
2
L
e
tan
2
+
E
x
wherein Le is a distance between an eye of the user and the lens, 2 is half of a field of view (FOV) of the display system, and Ex is a size of an exit pupil of the eye of the user.
24. The wearable display system according to claim 23, wherein the field of view is calculated according to:
9
F
O
V
=
2
tan
–
1
Y
i
2
L
wherein Yi is a size of the virtual image, and
L is a distance between the eye of the user and the virtual image.
25. The wearable display system according to claim 19, wherein:
10
>
c
=
sin
–
1
1
n
(
w
a
v
e
g
u
i
d
e
)
wherein is an angle of incidence of the signal on the lens, c is a critical angle of total reflection within the waveguide, and n(waveguide) is an index of refraction of the waveguide.
26. A binocular wearable display system comprising:
a plurality of display panels to display a signal; and
a waveguide to receive the signal from the display panels and propagate the signal therein, the waveguide comprising first and second ends to receive the signal and a side, an angle formed between the ends and the side allowing total reflection of the signal within the waveguide.
27. The wearable display system according to claim 26, wherein the signal is light, and the display system further comprises:
a frame to mount the waveguide;
a plurality of frame arms extending from the frame;
a plurality of light sources mounted on the frame arms to emit the light; and
a plurality of reflection units to reflect the emitted light to the waveguide.