1. An optical cavity enhanced turbidimeter comprising:
an optical source configured to emit a beam having a predetermined wavelength;
a vessel having a liquid sample;
an optical cavity containing first and second highly reflective mirrors facing each other, the vessel being disposed between the first and second mirrors, the first mirror to accept and allow the beam to repeatedly pass through the liquid sample and to the second mirror, the second mirror to accept and allow the beam to repeatedly pass through the second mirror to an optical detector;
the optical detector configured to measure an intensity of a beam output from the optical cavity after the beam passes through the liquid sample repeatedly, where the optical detector has a sufficiently quick response time to measure the intensity of exponentially attenuating light provided by the beam output upon passing through the liquid sample;
a controller configured to calculate an attenuation rate of the beam output, where the turbidity of the liquid sample is determined by the scattering level of light having a wavelength not corresponding to the absorption line of the target material in the liquid sample.
2. The optical cavity enhanced turbidimeter of claim 1, wherein the optical source emits a pulse beam or a beam having a steep intensity gradient.
3. The optical cavity enhanced turbidimeter of claim 1, further comprising:
a digital-analog converter converting an intensity of a beam detected by the optical detector into a digital signal; and
a plurality of valves controlling supply and discharge of a liquid sample to and from the vessel.
4. The optical cavity enhanced turbidimeter of claim 1, wherein the optical source is configured to emit a plurality of beams.
5. The optical cavity enhanced turbidimeter of claim 1, wherein a converter is configured to generate an electrical signal for controlling an optical switch coupled to the optical source.
6. The optical cavity enhanced turbidimeter of claim 1, wherein the vessel is formed of glass or plastic to provide minimal optical absorption and scattering of the beam.
7. A method of measuring turbidity using an optical cavity, the method comprising:
emitting a beam having a predetermined wavelength;
inputting the beam to a side of an optical cavity containing first and second highly reflective mirrors facing each other;
repeatedly transmitting the beam through a liquid sample contained in a vessel by repeatedly reflecting the beam between both sides of the optical cavity using the first and second mirrors, the vessel being disposed between the first and second mirrors;
outputting the beam through the other side of the optical cavity;
measuring an intensity of the beam output from the optical cavity with an optical detector, the optical detector having sufficiently quick response time to measure the intensity of exponentially attenuating light provided by the beam output upon passing through the liquid sample; and
calculating an attenuation rate of the beam using a controller, the controller configured to calculate the attenuation rate of the beam output, where the turbidity of the liquid sample is determined by the scattering level of light having a wavelength not corresponding to the absorption line of the target material in the liquid sample.
8. The method of claim 7, wherein the beam is a pulse beam or has a steep intensity gradient.
9. The method of claim 7 further comprising:
filling and draining the vessel with the liquid sample using at least one valve to control the amount of liquid sample inside the vessel.
10. The method of claim 7, wherein the vessel is formed of glass or plastic to provide minimal optical absorption and scattering of the beam.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
We claim:
1. Apparatus for pulling a fiber optical coupler to achieve a reduced diameter fused region, comprising:
first and second stages operative to hold the fibers on either side of the fused region, with at least one of the stages being moveable relative to the other;
a furnace positioned relative to the fused region;
a tensometer to determine the tension of the fibers between the stages; and
a controller operative to monitor the tension on the fibers and increase the distance between the stages when the tension falls to a predetermined threshold.
2. The apparatus of claim 1, wherein both stages move apart on a controlled basis enabling the furnace to remain stationary at least along the length of the fibers.
3. The apparatus of claim 1, wherein:
only one of the stages is moveable, but the furnace is also moveable; and
the controller is further operative to move the furnace along the fibers so that it remains positioned relative to the fused region.
4. The apparatus of claim 1, wherein:
the furnace is moveable a t least away from the fused region; and
the controller is further operative to maintain a consistent tension on the fibers by the moving the furnace away from the fused region as the distance between the stages is increased.
5. Apparatus for pulling a fiber optical coupler to achieve a reduced diameter fused region, comprising:
first and second stages operative to hold the fibers on either side of the fused region, with at least one of the stages being moveable relative to the other;
a furnace which is moveable at least away from the fused region;
a tensometer to determine the tension of the fibers between the stages; and
a controller operative to perform the following functions:
a) monitor the tension on the fibers and increase the distance between the stages when the tension falls to a predetermined threshold; and
b) move the furnace away from the fused region as the distance between the stages is increased to maintain a consistent tension on the fibers.
6. The apparatus of claim 5, wherein both stages move apart on a controlled basis enabling the furnace to remain stationary at least along the length of the fibers.
7. The apparatus of claim 5, wherein:
only one of the stages is moveable, but the furnace is also moveable; and
the controller is further operative to move the furnace along the fibers so that it remains positioned relative to the fused region.
8. A method of pulling a fiber optical coupler to achieve a reduced diameter fused region, comprising the steps of:
heating the fused region;
monitoring the tension on the fibers; and
pulling the fibers when the tension on the fibers reaches a predetermined threshold.
9. The method of claim 8, wherein both stages are moved apart on a controlled basis while keeping the furnace remains stationary.
10. The method of claim 8, wherein one of the stages and the furnace is moved such that the furnace remains positioned relative to the fused region.
11. The method of claim 8, wherein the furnace is moved away from the fused region as the distance between the stages is increased so as to maintain a consistent tension on the fibers.
12. A method of pulling a fiber optical coupler to achieve a reduced diameter fused region, comprising the steps of:
providing first and second stages operative to hold the fibers on either side of the fused region, with at least one of the stages being moveable relative to the other;
providing a furnace which is moveable at least away from the fused region;
monitoring the tension on the fibers and increasing the distance between the stages when the tension falls to a predetermined threshold; and
moving the furnace away from the fused region as the distance between the stages is increased to maintain a consistent tension on the fibers.
13. The method of claim 12, including the step of moving both stages apart on a controlled basis while keeping the furnace stationary.
14. The method of claim 12, including the step of moving one of the stages and the furnace so that the furnace remains positioned relative to the fused region.