WO2008079202A1

WO2008079202A1 - Measuring fluid quantities, blending liquid constituents, and dispensing blends

Info

Publication number: WO2008079202A1
Application number: PCT/US2007/025558
Authority: WO
Inventors: Aleksander Owczarz; Robert Knop; Mike Ravkin; John M. De Larios
Original assignee: Lam Research Corporation
Priority date: 2006-12-19
Filing date: 2007-12-14
Publication date: 2008-07-03
Also published as: TW200842327A

Abstract

An apparatus for measuring a fluid volume within a vessel is disclosed. The apparatus including a vessel having a sensor window and an interior chamber capable of holding a fluid, the interior chamber having a cross-sectional area. The apparatus also includes a sensor coupled to the vessel, the sensor having an active area interfaced with the sensor window. The sensor is capable of measuring a height of the fluid when the fluid is in the vessel. Wherein the fluid volume, when present in the vessel, is capable of being measured using the height of the fluid measured by the sensor and the cross-sectional area of the interior chamber.

Description

MEASURING FLUID QUANTITIES, BLENDING LIQUID CONSTITUENTS, AND DISPENSING BLENDS by Inventors

Aleksander Owczarz, Robert Knop, Mike Ravkin & John de Larios

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The present invention relates generally to methods and systems for precisely measuring a volume of fluid in a container, blending fluids with precision, and dispensing the same.

2. Description of the Related Art [0002] Two systems used to measure volumes of fluids are weighing systems and metering pumps. Weighing systems use load cells calibrated with the weight of a vessel to calculate the volume of fluid based on based on the change of mass of the vessel as fluid is added to the vessel. One problem that arises using weighing systems is the downtime of the system required to recalibrate because the system is susceptible to reaction forces from supply tubing and variations in vessel mass. Additionally, any changes in the mounting scheme of the vessel, or reconfiguration of the weighing system, can require additional downtime and extensive recalibration.

[0003] Metering pumps measure a fluid passing through a control volume. One downside to metering pumps is that individual metering pumps can be required for each fluid when multiple fluids are dispensed into a mixing vessel. With each fluid requiring a separate metering pump, the system complexity increases along with maintenance costs associated with the system. Furthermore, installation of metering pumps within the fluid supply lines increases the dead volume of fluid by requiring a specific volume of fluid to prime the metering pumps. [0004] In view of the forgoing, there is a need for a fluid measuring system that requires minimal recalibration and a system that does not require individual pumps having increased dead volumes to dispense fluid into a vessel. SUMMARY

[0005] In one embodiment, an apparatus for measuring a fluid volume within a vessel is disclosed. The apparatus includes a vessel having a sensor window and an interior chamber capable of holding a fluid, where the interior chamber has a cross-sectional area. The apparatus also includes a sensor coupled to the vessel, and the sensor has an active area interfaced with the sensor window. The sensor is capable of measuring a height of the fluid when the fluid is in the vessel. Wherein the fluid volume, when present in the vessel, is capable of being measured using the height of the fluid measured by the sensor and the cross- sectional area of the interior chamber. [0006] In another embodiment, an apparatus for measuring a fluid volume within a vessel is disclosed. The apparatus includes a vessel having an interior chamber with a cross-sectional area and a first sensor window. The vessel has a second sensor window, where the second sensor window is positioned at an opposite side from the first sensor window. The apparatus also includes a float within the vessel. The float having a first surface visible from the first sensor window and the float having a second surface visible from the second sensor window. The apparatus further includes a first sensor coupled to the vessel, and the first sensor has an active area interfaced with the first sensor window. The first sensor is capable of measuring a distance to the first surface of the float. A second sensor coupled to the vessel is also included in the apparatus. The second sensor having an active area interfaced with the second sensor window. The second sensor is capable of measuring a distance to the second surface of the float. Wherein the fluid volume, when present in the vessel, is capable of being measured using the height of the float suspended in the fluid volume as measured by the first and second sensors and the cross-sectional area of the interior chamber. [0007] In yet another embodiment, an apparatus for measuring a fluid volume within a vessel is disclosed. The apparatus includes a vessel having a sensor window and an interior chamber capable of holding a fluid, where the interior chamber has a cross-sectional area. A float is provided within the vessel, and the float has a surface visible from the sensor window. A sensor is further coupled to the vessel, and the sensor has an active area interfaced with the sensor window, where the sensor is capable of measuring a distance to the first surface of the float. Wherein the fluid volume, when present in the vessel, is capable of being measured using the height of the float suspended in the fluid volume as measured from the sensor and the cross-sectional area of the interior chamber. [0008] Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS [0009] The invention, together with further advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings.

[0010] Figure IA is a schematic of vessel and apparatus to measure the volume of a fluid in the vessel in accordance with one embodiment of the present invention

[0011] Figure IB is a schematic of a vessel configured to measure the volume of a fluid in the vessel in accordance with one embodiment of the present invention.

[0012] Figure 2A is a cross-section schematic showing a vessel configured to measure the volume of a fluid containing solids in accordance with one embodiment of the present invention.

[0013] Figure 2B - 2G are schematics showing float designs in accordance with embodiments of the present invention.

[0014] Figures 3A-3D are schematics showing various float configurations in accordance with multiple embodiments of the present invention.

[0015] Figure 4 is a schematic showing an apparatus for mixing, storing and applying fluids in accordance with one embodiment of the present invention. [0016] Figure 5 is a schematic showing an apparatus for mixing, storing and applying fluids in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION [0017] An invention is disclosed for the precision measurement and dispensing of fluids, mixtures of fluids and solids, mixtures of gas, liquids and solids, or the like, that may be held in a container. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order not to unnecessarily obscure the present invention.

[0018] Accurate and precise measurement of fluid volume and the dispending of fluids are necessary to achieve reproducible quantities, and desired mixtures of fluids, solids and fluids, and chemical compositions. Reducing the complexity of the systems capable of providing accurate and precise volumetric fluid measurements can increase productivity by decreasing the amount of setup and downtime needed for calibration and maintenance. Measuring the height of fluid within a container allows the volume to be calculated if the cross-section area of the container is known. One method to measure the height of a fluid is to mount a sensor capable of promulgating an energy pulse to the surface of the fluid and measuring either the reflected energy or the time it takes for the energy reflection to return to the sensor. A float may also be placed on the surface of the fluid to provide a more stable boundary capable of reflecting the energy pulse from the sensor. In other methods, multiple sensors may be used, where some sensors send energy pulses up through the fluid while other sensors direct energy pulses down toward the fluid.

[0019] Figure IA shows a schematic of vessel 100 and apparatus to measure the volume of a fluid in the vessel 100 in accordance with one embodiment of the present invention. A cross- section of the vessel 100 is shown in Figure IA. The cross-section shows the vessel 100 having an interior chamber 106. The interior chamber 106 may contain a fluid having a fluid surface 116 and a meniscus 108. The vessel 100 may also have an inlet 110 and an outlet 112. The inlet 110 can be used to introduce fluid to the interior chamber 106, while the outlet 112 can be used to evacuate fluid from the interior chamber 106. The locations of the inlet 1 10 and outlet 112 shown in Figure IA are illustrative and are not intended to be restrictive. In another embodiment, a vessel may have multiple inlets and multiple outlets. In other embodiments a vessel may have a single inlet and multiple outlets or a single outlet and multiple inlets.

[0020] The vessel 100 can also have a sensor window 102a. In one embodiment the sensor window 102a can be located at the bottom of the vessel 100 with an axial view to the top of the vessel. Throughout this application an axial view will be defined as a view providing a horizontal cross-section slice of the vessel as seen from either the top or bottom of the vessel. In another embodiment the sensor windows 102a may be located at the top of the vessel 100. In one embodiment a sensor 102 may be coupled to the vessel with an active area of the sensor 102 interfaced with the sensor window 102a. A seal 114 can be used to prevent fluid from leaking from the area around the sensor window 102a and the sensor 102 to the exterior of the vessel. Additional seals can also be used to prevent fluid from leaking around the inlet 110 and outlet 112. In one embodiment, the sensor 102 can be used to transmit an energy pulse, from the active area of the sensor 102, into a fluid within the inner chamber 106. The sensor 102 can detect and measure the energy pulse that is reflected from the fluid surface 116 and returned to the sensor 102. It should be understood that a sensor can be defined, built, or constructed in any number of ways, and particular implementations of a sensor having the capabilities of sensor 102 are commercially available. For example purposes the sensor 102 can be an ultrasonic sensor. Currently, similar sensors may be available from companies such as OMRON of Kyoto, Japan. Of course, other ultrasonic sensor manufacturers currently make sensors having the functionality defined herein.

[0021] In one embodiment, the height of fluid within the vessel can be calculated based on the time it takes for the energy pulse to return to the sensor. In another embodiment, the height of fluid within the vessel can be calculated based on the amount of energy that is returned to the sensor 102. In yet another embodiment both the time and the amount of energy returned to the sensor 102 may be used to calculate the volume of fluid within the vessel. The sensor 102 can communicate with a sensor control system 104 that can calculate the volume of fluid within the vessel based on the height of fluid measure by the sensor and a known cross-sectional area of the vessel. The calculations can be carried out by a program executed on a computing system or by circuitry. The calculation output can be presented digitally, displayed on a screen, output on a print out, or saved to a file.

[0022] Because the transmission rate of the energy pulse through the fluid may not be constant as fluids are blended and mixed, the sensor control system can also receive data from a sensor capable of measuring pressure, temperature and density. The sensor control system may be calibrated to compensate for pressure, temperature and density variation when calculating the volume of fluid within the vessel. In one embodiment the sensor 102 can incorporate the sensors for measuring pressure, temperature and density. In other embodiments there may be individual, multiple, or groups of sensors arranged throughout the vessel capable of measuring pressure, temperature or density. [0023] Since fluids of various densities may be mixed within a vessel, the sensor control system may include software that can modify or recalibrate the sensor and/or sensor control system based on the types of fluid within and the types of fluid entering the vessel. This type of dynamic recalibration may be necessary if the fluid height is being measured based on the time required for the energy pulse to return to the sensor. For example, if a first fluid has been introduced into the vessel and a second fluid is being added that will decrease the density of the blended fluid it may be possible to have the sensor output a stronger energy pulse. Similarly, the software used to calculate the height of the fluid within the vessel may need to compensate for density changes as fluids are blended and mixed. [0024] The sensor control system 104 can send and receive data to a computer control 124. Access and manipulation of the computer control 124 may be accomplished directly using a terminal integrated into the computer control 124 or from a remote terminal using a computer network. The computer control 124 can use the data from the sensor control system 104 to control a fluid input control 118 and a fluid output control 120. The fluid input control 118 and the fluid output control 120 are capable of controlling the respective inlet 110 and outlet 112. Fluid exiting the outlet 112 may be used in a fluid application system/device 112. In one embodiment the fluid application system/device 112 may be used for semiconductor plating or semiconductor cleaning operations. In another embodiment the vessel 100 may be used to mix fluids and the outlet 112 may be connected to a storage vessel.

[0025] Figure IB is a schematic of a vessel 100 configured to measure the volume of a fluid in the vessel in accordance with one embodiment of the present invention. Similar to Figure IA the vessel 100 has a sensor 102 with an active area capable of interfacing with a sensor window 102a. A seal 1 14, that can prevent leakage of fluid to the exterior of the vessel 100, may also surround the sensor 102. Additionally, the vessel 100 may also have sensor 102' with an active area capable of interfacing with a sensor window 102a'. In one embodiment the sensor window 102a and the sensor window 102a' are opposite one another as shown in Figure IB. In other embodiments, the sensor windows may not be configured to be opposite each other. For example the sensor windows 102 and 102a' may be offset so they are not inline with each other while still providing an axial view of the interior of the vessel.

[0026] As previously discussed, the sensor 102 is capable of sending an energy pulse through a fluid within the vessel and measuring the height of the fluid based on the methods previously discussed. Similarly, the sensor 102' is capable of sending an energy pulse through the volume of the vessel not occupied by fluid and measuring the height of the fluid based on the time it takes the energy pulse to reflect from the fluid surface 1 16. Alternatively, the sensor 102' may also measure the height of the fluid within the vessel by measuring the energy reflected from the surface of the fluid, or a combination of time and energy reflection. The configuration shown in Figure IB may be beneficial in a situation where fluids of varying different densities are mixed in the vessel 100. While the use of an additional sensors to measure temperature, pressure, and density may be used to compensate for the velocity of an energy pulse through the fluid and gas in the vessel, the additional measurement provided by using sensor 102' may also provide accurate volumetric measurements. The use of sensor 102' could also be used to assist in obtaining volumetric measurements when the use of sensor 102 would be impractical. An example of a situation where using sensor 102 would be impractical is if the vessel 100 contained a mixture of solids and fluids. In one embodiment the vessel 100 may contain a fluid capable of suspending solid material within the fluid. In such an embodiment it may be difficult to determine the distance to the fluid surface because the energy pulse from the sensor 102 could reflect off the suspended solid material.

[0027] Similar to Figure IA, the sensor 102 and the sensor 102' are connected to a sensor control system 104. The sensor control system 104 is connected to a computer control 124 that is capable of being networked and controlled from a remote location. As shown in this particular embodiment, the computer control 124 is connected to a fluid input control 118 and a fluid output control 120. As previously discussed, the fluid input control 118 can control the input of various fluids into the vessel 100. The fluid output control 120 can control the output of fluid from the vessel 100 to a fluid application device 122. As previously discussed the fluid application device 122 can be a variety of devices including, but not limited to, semiconductor processing equipment and other equipment and devices where precision measurement and dispensing of fluids is desired. Other fields where precision measurements and dispending of fluids may be desired include, but are not limited to, pharmaceutical research and manufacturing, medical fields, petroleum refining and distillation, chemical manufacturing, and food preparation. [0028] Figure 2A is a cross-section schematic showing a vessel 200 configured to measure the volume of a fluid containing solids in accordance with one embodiment of the present invention. Similar to the embodiment shown in Figure IB, the vessel 200 includes sensors 102 and 102a'. The sensors 102 and 102' can have an active area capable of viewing the internal contents of the vessel 200 through sensor windows 102a and 102a' respectively. The sensors 102 and 102' can be controlled by a sensor control system 104. Also similar to the embodiments shown in Figures IA - IB is the vessel 200 including an inlet 110 and an outlet 112. A float 202 is capable of floating on a fluid surface 204.

[0029] The float 202 can provide a more uniform surface capable of reflecting energy from the sensors 102 and 102'. The use of the float 202 may become necessary if the fluid within the vessel contains solids, gas bubbles or other characteristics that make the surface unstable or unreliable for returning an accurate height measurement. When using the float 202, the sensor control system 104 may be used to calculate the height of the fluid within the vessel 200 by measuring the distance from the sensors 102 and 102' to the float. In one embodiment the sensor 102' can measure the distance to the top of float 202. Conversely, the bottom sensor 102 may be used to measure the distance from the sensor to the bottom of the float 202. A measurement of the fluid height can be determined from the measurement from sensor 102 or 102' or both measurements may be used. For example, the sensor 102 can measure the distance Yi while the sensor 102' can measure the distance Y₂. A dimension Y₃ of the float 202 can be input into the sensor control system 104 along with the volume of fluid displaced by the float 202 thus allowing the calculation of the fluid height within the vessel 200. Using the cross-sectional area of the vessel 200 and the calculated fluid height within the vessel 200, the volume of fluid within the vessel 200 may be calculated. [0030] Figure 2B - 2G are schematics showing float 202 designs in accordance with embodiments of the present invention. As shown in Figure 2B the float 202 can include hollow areas 203. The hollow areas 203 can provide buoyancy for the float 202 along with providing different energy reflection that may be used to calculate the distance to the float. 202. As shown in Figure 2C a float 202a may be as simple as a block that rests partially submerged in the fluid in accordance with one embodiment of the present invention. However, different float configurations may be used to accomplish the task of reflecting energy back to the sensor. A float 202b, as illustrated in Figure 2D, can have sloped sides to minimize the possibility of allowing fluid to collect on the top surface. As shown in Figure 2E, the float 202c has multiple flat areas submerged in the fluid. The sensor control system can be programmed to recognize different energy return patterns from the float and be calibrated to calculate the distance to the float 202c. A float 202d as shown in Figure 2F can used the various height levels associated with the surface on top of the fluid as different reference points to calculate the fluid level. Similar to Figure 2D, the different heights can allow the sensor control system to compensate for a fluid resting on the surface of the float 202d. A float 202e, illustrated in Figure 2G, shows another variation of different levels of flat surfaces to compensate for movement of the float.

[0031] In one embodiment, the vessel 200 can contain fluids used in the processing of semiconductor substrates and to minimize possible sources of contaminates, the float 202 may be manufactured from materials such as quartz or plastic. Metallic materials may also be used to fabricate the float 202 when potential metallic contamination from the float 202 does not detrimentally affect later processes or when the fluids in the vessel are non-reactive with the metallic material.

[0032] Figures 3A-3D are schematics showing various float configurations in accordance with multiple embodiments of the present invention. The views illustrated in Figures 3 A-3D are top views looking into a vessel 200 that is open. Figure 3A illustrates a vessel 200 with a circular cross-section that has one float 202. Figure 3B illustrates a vessel 200 with a circular cross-section containing three floats 202 while Figure 3C illustrates another vessel 200 with a circular cross-section with five floats 202. The inclusion of multiple floats 202 may necessitate the use of additional sensors. The additional sensors may be necessary to promulgate an energy pulse that can be returned by the float at particular fluid levels. Conversely, a single sensor can be used and the ability to return energy from a limited number of floats may assist in the calculation of the fluid level. Figure 3D illustrates a vessel 200 with a rectangular cross-section containing a single float 202 in accordance with one embodiment of the present invention. While the examples shown in Figures 3A-3D and previously discussed have constant cross-sectional areas it would be possible to use vessel with a variable cross-sectional area as well. As long as the energy pulse from the sensor can travel to the surface of the fluid, or a float on the surface of the fluid, and be partially reflected back to the sensor, the height of the fluid can be calculated. [0033] Figure 4 is a schematic showing an apparatus for mixing, storing and applying fluids in accordance with one embodiment of the present invention. A holding vessel 400 and a holding vessel 402 can contain different fluids. The holding vessels 400 and 402 can be connected to a mixing vessel 410. The mixing vessel 410 is capable of measuring the input of the respective chemicals from the holding vessels 400 and 402 using a system similar to those previously discussed in Figures IA, IB and 2 A. The mixing vessel 410 may include a single or multiple floats along with a sensor or a plurality of sensors in a variety of configurations. The mixing vessel 410 can also measure the output of the mixed fluid to a holding vessel 408 using the volumetric measuring system previously discussed. Similarly, the holding vessel 408 can use the previously discussed volumetric measuring system to measure both the input from the mixing vessel 410 and the output to a process station 404. In the embodiment shown in Figure 4 the process station 404 can be used to process a substrate 406. [0034] In one embodiment the computer control can work with the sensor control system to control the input and output of a fluid from the holding vessel 400. For example, the computer control system and sensor control system can be used to measure the input of a fluid into the mixing vessel from the holding vessel 400. Subsequently, fluid from holding vessel 402 can be added to the mixing vessel 410. In other embodiments additional fluids may be added to the mixing vessel 410. After sufficient mixing the mixing vessel can output the fluid to the holding vessel 408. The volumetric measuring system integrated into either the holding vessel 408 or mixing vessel 110 can measure the volume of fluid transferred from the mixing vessel 410 to the holding vessel 408. In another embodiment the volumetric measuring systems in the respective vessels can work together to dispense a particular volume of fluid into the holding vessel 408. [0035] In another embodiment connecting a pressure regulator to the holding vessel 408 and computer control system can allow the volumetric measuring system to perform as a flow rate meter. The pressure regulator can be used to either pressurize the vessel or use vacuum suction to dispense fluid from the vessel. The computer control system can control the pressure regulator and the volumetric measuring system can measure the decrease of fluid volume within the holding vessel as fluid is dispensed. Correlating the decrease in volume with a change in time permits the flow rate of the fluid. Thus, the computer control system can be programmed to output a particular flow rate based on feedback from the pressure regulator and the flow rate calculated using the volumetric measuring system. [0036] Figure 5 is a schematic showing an apparatus for mixing, storing and applying fluids in accordance with one embodiment of the present invention. Holding vessels 500, 502 and 504 can be connected to a mix and hold vessel 510 configured to measure fluids as previously described. The mix and hold vessel 510 is capable of controlling input to holding vessels 500, 502 and 504 using the sensor control system and the computer control. Volumetric output and flow rate of fluid from the vessel to a process station 506 can also be measured and controlled using the sensor, sensor control system and computer control using previously discussed techniques. Additionally, the holding vessels 500, 502, and 504 can also be configured with sensors and sensor control systems. In another embodiment, multiple sensors from multiple vessels can be input into a single sensor control system. In an alternative embodiment, multiple sensor control systems may be used to control multiple sensors in multiple or single vessels.

[0037] The calculation of fluid volume within the vessel using one sensor or multiple sensors with or without a float or multiple floats can be accomplished using a computer and a computer program. As previously mentioned the sensors 102 and 102' can be connected to the sensor control system 104. The sensor control system 104 can also take input from additional sensors capable of measuring temperature, pressure and density of fluids within the vessel. Additionally, the sensor control system 104 can accept user-defined input specifying the rate of energy pulse propagation within various fluids and/or fluid mixtures at various temperatures, pressures, and densities. Alternatively, the sensor control system 104 can accept computer programs capable of calculating the rate of energy pulse propagation based on temperature, pressure and density for a variety of fluids that could be introduced into the vessel.

[0038] The computer program may be necessary to calculate the height of fluid within the vessel because fluids of varying density may be introduced to the vessel at different temperatures. Furthermore, the computer program may be necessary to compensate for dynamic changes in density as the fluids mix and, the mixing of fluids may be performed at various temperatures. Thus, the computer program can calculate the height of a first fluid when a first fluid is introduced into the vessel with a specific temperature, density, and viscosity. Similarly, when a second fluid is introduced into the vessel the computer will be able to calculate the volume of second fluid added to the vessel even if the second fluid has a different temperature, density and/or viscosity. The invention may be practiced with other computer system configurations including computing devices, portable hand-held devices, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers and the like. The invention may also be practiced in distributing computing environments where tasks are performed by remote processing devices that are linked through a network.

[0039] With the above embodiments in mind, it should be understood that the invention may employ various computer-implemented operations involving data stored in computer systems. These operations are those requiring physical manipulation of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. Further, the manipulations performed are often referred to in terms, such as producing, identifying, determining, or comparing. [0040] Any of the operations described herein that form part of the invention are useful machine operations. The invention also relates to a device or an apparatus for performing these operations. The apparatus may be specially constructed for the required purposes, such as the carrier network discussed above, or it may be a general purpose computer selectively activated or configured by a computer program stored in the computer. In particular, various general purpose machines may be used with computer programs written in accordance with the teachings herein, or it may be more convenient to construct a more specialized apparatus to perform the required operations. [0041] The invention can also be embodied as computer readable code on a computer readable medium. The computer readable medium is any data storage device that can store data, which can thereafter be read by a computer system. Examples of the computer readable medium include hard drives, network attached storage (NAS), read-only memory, random- access memory, FLASH based memory, CD-ROMs, CD-Rs, CD-RWs, DVDs, magnetic tapes, and other optical and non-optical data storage devices. The computer readable medium can also be distributed over a network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

[0042] Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims. What is claimed is:

Claims

1. An apparatus for measuring a fluid volume within a vessel, comprising: a vessel having a sensor window and an interior chamber capable of holding a fluid, the interior chamber having a cross-sectional area; a sensor coupled to the vessel, the sensor having an active area interfaced with the sensor window, the sensor capable of measuring a height of the fluid when the fluid is in the vessel; wherein the fluid volume when present in the vessel is capable of being measured using the height of the fluid measured by the sensor and the cross-sectional area of the interior chamber.

2. The apparatus as recited in claim 1, wherein the sensor window is one of an energy pulse transparent covering to the interior chamber of the vessel or an opening to the interior chamber of the vessel.

3. The apparatus as recited in claim 1, wherein the sensor window is positioned to provide the sensor an axial view of the vessel.

4. The apparatus as recited in claim 1, wherein the cross-sectional area of the interior of the vessel is either constant or variable.

5. The apparatus as recited in claim 1, further comprising: a sensor control system capable of processing sensor data.

6. The apparatus as recited in claim 5, further comprising: a fluid input control capable of controlling fluid input to the vessel; a fluid output control capable of controlling fluid output from the vessel; and a computer control capable of controlling the fluid input control and the fluid output control in response to signals from the sensor control system.

7. An apparatus for measuring a fluid volume within a vessel, comprising: a vessel having an interior chamber with a cross-sectional area, a first sensor window, and a second sensor window, the second sensor window positioned at an opposite side from the first sensor window; a float within the vessel, the float having a first surface visible from the first sensor window and the float having a second surface visible from the second sensor window; a first sensor coupled to the vessel, the first sensor having an active area interfaced with the first sensor window, the first sensor capable of measuring a distance to the first surface of the float; a second sensor coupled to the vessel, the second sensor having an active area interfaced with the second sensor window, the second sensor capable of measuring a distance to the second surface of the float; wherein the fluid volume when present in the vessel is capable of being measured using the height of the float suspended in the fluid volume as measured by the first and second sensors and the cross-sectional area of the interior chamber.

8. The apparatus as recited in claim 7, wherein the fist sensor window and second sensor window are one of an energy pulse transparent covering to the interior chamber of the vessel or an opening to the interior chamber of the vessel.

9. The apparatus as recited in claim 7, wherein the first and second sensor windows are positioned to provide the sensor an axial view of the vessel.

10. The apparatus as recited in claim 7, wherein the cross-sectional area of the interior of the vessel is either constant or variable.

11. The apparatus as recited in claim 7, further comprising: a sensor control system capable of processing sensor data.

12. The apparatus as recited in claim 11, further comprising: a fluid input control capable of controlling fluid input to the vessel; a fluid output control capable of controlling fluid output from the vessel; and a computer control capable of controlling the fluid input control and the fluid output control in response to signals from the sensor control system.

13. An apparatus for measuring a fluid volume within a vessel, comprising: a vessel having a sensor window and an interior chamber capable of holding a fluid, the interior chamber having a cross-sectional area; a float within the vessel, the float having a surface visible from the sensor window; a sensor coupled to the vessel, the sensor having an active area interfaced with the sensor window, the sensor capable of measuring a distance to the first surface of the float; wherein the fluid volume when present in the vessel is capable of being measured using the height of the float suspended in the fluid volume as measured from the sensor and the cross-sectional area of the interior chamber.

14. The apparatus as recited in claim 13, wherein the sensor window is one of an energy pulse transparent covering to the interior chamber of the vessel or an opening to the interior chamber of the vessel.

15. The apparatus as recited in claim 13, wherein the sensor window is positioned to provide the sensor an axial view of the vessel.

16. The apparatus as recited in claim 13, wherein the cross-sectional area of the interior of the vessel is either constant or variable.

17. The apparatus as recited in claim 13, further comprising: a sensor control system capable of processing sensor data.

18. The apparatus as recited in claim 17, further comprising: a fluid input control capable of controlling fluid input to the vessel; a fluid output control capable of controlling fluid output from the vessel; and a computer control capable of controlling the fluid input control and the fluid output control in response to signals from the sensor control system.