1. An optical fiber comprising:
a substantially pure silica core;
a first intermediate layer comprising a doped silica at least partially surrounding the core;
a second silica layer at least partially surrounding the first intermediate layer, wherein the second silica layer is not doped; and
a hydrogen resistant layer at least partially surrounding the second silica layer.
2. The optical fiber of claim 1, wherein the hydrogen-resistant layer is substantially free of silica.
3. The optical fiber of claim 1, wherein the hydrogen-resistant layer comprises carbon.
4. The optical fiber of claim 1, wherein the first intermediate layer is doped with a material comprising fluorine or boron.
5. The optical fiber of claim 1, wherein the first intermediate layer is doped with a material comprising germanium or phosphorous.
6. The optical fiber of claim 1, further comprising a secondary coating substantially covering the optical fiber.
7. The optical fiber of claim 1, wherein the hydrogen-resistant layer comprises metal.
8. The optical fiber of claim 7, wherein the metal is selected from the group consisting of copper, copper alloys, aluminum, aluminum alloys, gold and gold alloys.
9. The optical fiber of claim 1, wherein the hydrogen-resistant layer comprises a ceramic material.
10. The optical fiber of claim 9, wherein the ceramic material comprises silicon nitride or silicon carbide.
11. The optical fiber of claim 1 comprising means for reducing hydrogen-induced attenuation at both relatively low and relatively high temperatures.
12. The optical fiber of claim 11, wherein the relatively low temperatures are less than about 170 degrees C.
13. The optical fiber of claim 11, wherein the relatively high temperatures are greater than about 170 degrees C.
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 cooling device used in an image forming device that forms images on a recording medium and thermally fixes the images on the recording medium, the cooling device comprising:
a cooling roller;
a support member that contacts the cooling roller to define a nip portion between the cooling roller and the support member, wherein
the cooling roller cools a recording medium at the nip portion between the cooling roller and the support member, a temperature of the cooling roller is set to 85 C. or greater.
2. The cooling device according to claim 1, wherein the temperature of the cooling roller is set to 100 C. or greater.
3. The cooling device according to claim 1, wherein a temperature coefficient of the cooling roller is set to 0.73 or greater, the temperature coefficient being equal to (TinTout)(TinTc), wherein:
Tin is a temperature of the recording medium when entering the nip portion;
Tout is a temperature of the recording medium when leaving the nip portion; and
Tc is the temperature of the cooling roller.
4. The cooling device according to claim 1, wherein a temperature coefficient of the cooling roller is set to 0.73 or greater, the temperature coefficient being equal to (lh)Cv), wherein
h is a cooling capacity of the cooling roller;
is a density of the recording medium;
C is a specific heat of the recording medium;
is a thickness of the recording medium; and
v is a peripheral velocity of the cooling roller.
5. The cooling device according to claim 1, wherein the temperature of the cooling roller is set equal to or greater than a minimum temperature at which dew condensation occurs.
6. The cooling device according to claim 1, further comprising a fan that discharges air from a region in vicinity of the cooling roller, wherein the recording sheet passes through the region.
7. The cooling device according to claim 6, further comprising a heat-radiation member that radiates heat of the cooling roller, wherein the air discharged from the region by the fan blows against the heat-radiation member.
8. A cooling device used in an image forming device that forms images on a recording medium and thermally fixes the images on the recording medium, the cooling device comprising:
a cooling roller;
a support member that contacts the cooling roller to define a nip portion between the cooling roller and the support member, wherein
the cooling roller cools a recording medium at the nip portion between the cooling roller and the support member, and
a temperature coefficient of the cooling roller is set to 0.73 or greater, the temperature coefficient being equal to (TinTout)(TinTc), wherein:
Tin is a temperature of the recording medium when entering the nip portion;
Tout is a temperature of the recording medium when leaving the nip portion; and
Tc is the temperature of the cooling roller.
9. An image forming device comprising:
an image forming unit that forms images on a recording medium;
a fixing unit that thermally fixes the images on the recording medium; and
a cooling device that cools the recording medium, the cooling device including a cooling roller and a support member that contacts the cooing roller to define a nip portion between the cooling roller and the support member, wherein
the cooling roller cools a recording medium at the nip portion sandwiched between the cooling roller and the support member, a temperature of the cooling roller is set to 85 C. or greater
10. The image forming device according to claim 9, wherein the temperature of the cooling roller is set 100 C. or greater.