UV-cure of coatings for an optical fiber with a laser
An apparatus and method efficiently focuses laser light to a target fiber to rapidly and evenly cure a coating on the fiber and to increase a draw rate for the fiber. The laser light is expanded and refocused to a strip of light having a diameter that is a multiple of the fiber diameter. The strip of light is applied to one side of the fiber and a reflection of the strip of light is focused to a second side of the fiber to provide uniform radiation of the fiber.
1. An apparatus for photocuring a coating on a target fiber, comprising:
a laser source;
a beam expander for expanding an output of the laser source;
a first lens operable to focus an output of the beam expander on the coating disposed on the target fiber, wherein the coating is responsive to a wavelength of light emitted from the laser source; and
a concave optical element disposed on an opposite side of the target fiber relative to the beam expander and said first lens, wherein the concave optical element comprises a half cylinder mirror.
2. The apparatus of claim 1 , wherein said first lens comprises a plano-concave lens with a planar side disposed towards said beam expander.
3. The apparatus of claim 1 , wherein said laser source outputs radiation in a visible light range.
4. The apparatus of claim 3 , wherein said laser source is a continuous wave laser.
5. The apparatus of claim 3 , wherein said laser source is a pulsed laser.
6. The apparatus of claim 3 , wherein the laser source outputs radiation in a range of 400–800 nm.
7. The apparatus of claim 1 , further comprising a magnetic field source which is operable to apply a magnetic field about said target fiber.
8. The apparatus of claim 7 , wherein said laser source is a continuous wave laser emitting light in the UV range between 300 and 400 nm.
9. The apparatus of claim 1 further comprising a second lens disposed between said first lens and said concave optical element.
10. The apparatus of claim 9 , wherein said second lens comprises a cylindrical lens.
11. The apparatus of claim 10 , wherein said laser source is disposed at least 2 meters away from said target fiber.
12. The apparatus of claim 1 , wherein said laser source is disposed at least 2 meters away from said target fiber.
13. The apparatus of claim 1 , wherein the laser source outputs radiation in a UV radiation range.
14. The apparatus of claim 1 , further comprising the target fiber having the coating disposed thereon.
15. A method of photocuring a coating on an optical fiber, comprising:
expanding a laser beam to produce an expanded diameter laser beam;
focusing the expanded diameter laser beam to a strip of light having a diameter that is larger than a diameter of the fiber onto a front side of the fiber to cure the fiber; and
reflecting the laser beam strip of light to a rear side of the fiber, wherein reflecting the laser beam to the rear side of the fiber includes reflecting the laser beam with a half cylinder mirror.
16. The method according to claim 15 , further comprising: applying a magnetic field around the fiber.
17. The method according to claim 15 , wherein the laser beam continuously outputs light in a visible portion of electromagnetic spectrum.
18. The method according to claim 15 , wherein the laser outputs pulses of visible light.
19. The method according to claim 15 , wherein said laser beam emits in the range of 300–400 nm.
20. The method according to claim 15 , wherein said laser beam emits radiation ir the range of 400–800 nm.
21. The method according to claim 15 , wherein a source of said laser beam is disposed at least 2 meters away from the fiber.
22. A method of photocuring a coating on an optical fiber, comprising:
expanding a laser beam to produce an expanded diameter laser beam;
focusing the expanded diameter laser beam to a strip of light having a diameter that is larger than a diameter of the fiber onto a front side of the fiber to cure the fiber; and
reflecting the laser beam strip of light to a rear side of the fiber, wherein the expanding, the focusing and the reflecting are provided by expanding, focusing and reflecting elements each aligned in a linear disposition with each other.