Abstract:
An optical sensor for a conventional tank gauge designed to allow a user to remotely check the liquid level of a tank without the need for a visual inspection. Using an emitter circuit board with a plurality of photoemitters and a detector circuit board with a plurality of photodetectors, the optical sensor can fit over a conventional tank gauge without disturbing the gauge. The circuit boards can be attached to an optical sensor frame, which can be adjusted on the conventional tank gauge by a height adjustment screw and a series of set screws. Alternatively, one or more sliders can be used to maintain proper alignment. Analog data generated from the photodetectors can be digitized using a microcontroller and can be made available for viewing on a stationary or mobile device via an integrated network connection.

Description:
FIELD OF THE INVENTION 
       [0001]    The present device relates to an optical sensor that can be used to read the levels of liquid measured by a conventional tank gauge. U.S. application Ser. No. 14/804,677 is incorporated by reference in its entirety. 
       BACKGROUND 
       [0002]    Many conventional gauges require direct visual reading to determine the current level of fluid inside a tank, such as those used to store home heating oil. This task may or may not be convenient to conduct on a routine basis depending on the tank location. Furthermore, ongoing manual readings of a tank gauge are necessary to detect when the contents reach a critical level. 
         [0003]    One method to overcome this problem involves the removal of an existing conventional gauge and installation of an electronic gauge that analyzes sound waves prior to wirelessly transmitting notification signals to a receiver located within close proximity. Should such an electronic gauge fail during use the owner/operator has no secondary method of reading the tank level until the defective gauge is replaced with a new one or a conventional gauge is reinstalled. Secondly, this design requires the owner/operator to properly install the electronic replacement gauge onto the tank so the liquid contents do not evaporate through an improper seal. 
         [0004]    In addition to using sound waves to remotely monitor the level of a tank, a different method integrates reed switches that turn on and off when a magnetic field is present. Such a design requires the temporary removal of the measurement vial of an existing conventional gauge; installation of a magnet holder on top of the indicator; placement of a magnet on the holder; and re-attachment of the measurement vial. Once the magnet has been installed a sensor consisting of switches and other electronic components is strapped to the measurement vial for the purpose of turning designated circuits on and off. The state of each circuit is transmitted via wire cable to a second device for interpretation and level indication. Similar to the sound wave method, this design requires the owner/operator to properly install the required magnet on top of the gauge indicator and reattach the measurement vial onto the tank so the liquid contents do not evaporate through an improper seal. Furthermore, this system does not allow the owner/operator to monitor the status remotely from a location beyond the linear distance of cable installed between the transmitter and receiver. 
         [0005]    What is needed is an optical sensor that can be fitted over a conventional tank gauge in order to provide remote access to the measurements generated by the conventional gauge. 
       SUMMARY OF THE INVENTION 
       [0006]    It is an aspect of the disclosure to provide an optical sensor that can be fitted over a conventional tank gauge in order to provide remote access to the measurements generated by the conventional gauge. These together with other aspects and advantages, which will be subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein life numerals refer to like parts throughout. 
     
    
     
       A BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Further features and advantages of the present device, as well as the structure and operation of various embodiments of the present device, will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which: 
           [0008]      FIG. 1  is a cross section view of a conventional tank gauge without an optical sensor, according to an embodiment. 
           [0009]      FIG. 2  is a perspective view of an optical sensor, according to an embodiment. 
           [0010]      FIG. 3  is an exploded view of an optical sensor with molded enclosures, according to an embodiment. 
           [0011]      FIG. 4A  is a cross section view of a conventional tank gauge with an optical sensor in the process of adjustment, according to an embodiment. 
           [0012]      FIG. 4B  is a cross section view of a conventional tank gauge with an optical sensor in the process of adjustment, according to an embodiment. 
           [0013]      FIG. 5  is a perspective view of an optical sensor, according to an alternate embodiment. 
           [0014]      FIG. 6  is an exploded view of an optical sensor with molded enclosures, according to an alternate embodiment. 
           [0015]      FIG. 7  is an example schematic diagram of a circuit implementing an optical sensor, according to an embodiment. 
           [0016]      FIG. 8  is an example schematic diagram of a circuit implementing an optical sensor, according to an embodiment. 
           [0017]      FIG. 9  is a block diagram illustrating the functions of an optical sensor, according to an embodiment. 
           [0018]      FIG. 10  is a perspective view of an optical sensor, according to an alternate embodiment. 
           [0019]      FIG. 11  is a top view of an optical sensor attached to a small conventional tank gauge, according to an alternate embodiment. 
           [0020]      FIG. 12  is a top view of an optical sensor attached to a large conventional tank gauge, according to an alternate embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    The present device is a different type of optical sensor that allows an existing conventional tank gauge to remain in place without disturbance and determines the level of a gauge indicator by monitoring photon beams that travel horizontally through a glass (or another translucent material, such as plastic) vial. More specifically, level detection is achieved by checking the state of a photon beam that travels from a photoemitter through a measurement vial to a corresponding photodetector, such as but not limited to a phototransistor, photodiode, etc., on the opposite side. If the photon beam is detected by a photodetector it means no obstruction is present, which is due to the indicator and/or stem resting below a given line of sight; therefore, the corresponding LED is dimmed or turned off. If the photon beam is not detected by a photodetector it means an obstruction is present, which is due to the indicator and/or stem resting on or above the line of sight; therefore, the corresponding LED is illuminated. Using an array of photoemitters, photodetectors and LEDs, the proposed invention is capable of monitoring one or more levels between full and empty. To prevent a photodetector from detecting a photon beam from a photoemitter other than its designated mate, the sides or surface of each emitter and photodetector must be shrouded or masked with an opaque material or compound to form a narrow aperture for the optical line of sight. 
         [0022]    The physical framework of the invention includes a lower mounting ring that forms a base. Rising up from the base are: two opposing printed circuit boards (PCB) that may or may not be enclosed or covered; two or more vertical support rods for structural integrity and vertical alignment against a measurement vial; a cap with a countersunk section on the underside to form an upper chamber that receives the top of a measurement vial; and a screw threaded through the cap that can be turned to adjust the vertical height. Also, two or more set screws are provided in both the base and cap to press against the measurement vial once the invention&#39;s final position has been determined. 
         [0023]    Once the primary embodiment has been supplied power the state of each photodetector will serve two main functions: 1) change the state of each corresponding LED indicator on the same circuit to provide an immediate on-site visual check that the device is working correctly; and 2) increase or decrease the voltage output within a range on the corresponding circuit that traces back to a microcontroller for analog to digital conversion. In addition to the arrays of photoemitters, photodetectors and LEDs used for this embodiment, additional components are attached to the PCBs, such as but not limited to resistors, headers, connectors and wire/cable. The cable connected to the sensor provides wires for the appropriate direct current (DC) supply voltage, ground, and monitoring the output voltage from each photodetector. At the opposite end of the cable a connection is made to a second device that houses supporting electronic hardware and software to capture the sensor data; and can emit an audible sound when a critical level is reached on the gauge or for some other notification purpose. In addition, this second device can function as an embedded server on a local network or a web client to routinely send the latest sensor data, along with unique identifiers, through the Internet to a remote server. The network connection may be made using wireless or wired technology, such as Bluetooth, WiFi, or Ethernet. Once the data is received by the embedded or remote server it can be analyzed and stored in one or more different types of memory and/or formats, such as, but not limited to, a database. If the server determines data from a sensor meets certain criteria an automated message will be communicated to a user as a text message sent to a phone and/or an email message. The server will also host a web site to provide each unique user with access to various services, such as but not limited to: 1) displaying graphics and text that represent the current status of the sensor; 2) turn automated messaging on/off; and 3) change the interval between client-server communications. Access to the server can be accomplished using nothing more than a web browser on numerous types of devices (e.g. computer, tablet, smartphone, etc.) with local network and/or Internet access. Alternatively, access to the server can be accomplished using an application developed for various operating systems. 
         [0024]    In one alternative embodiment of the invention a separate microcontroller is integrated directly into the sensor to handle signal processing from each detector prior to transferring compiled data to the supporting hardware that functions predominately as an embedded server or web client. This compartmentalization approach allows a single embedded server or web client design to interface with many variations of the proposed invention without requiring significant changes. 
         [0025]    Overall, the key electronic components found in the primary embodiment include, but are not limited to, arrays of photoemitters and phototransistors (photodetectors or detectors); LEDs for status indication; resistors with varying values; headers; connectors; wire/cable; one or more microcontrollers; an integrated circuit for network connection using wired and/or wireless technology; antenna; crystals; power supply jack; voltage regulator; capacitors; transistors; diodes; buttons; slide switches; and covers or housings to enclose the various PCBs. 
         [0026]      FIG. 1  is a cross section view of a conventional tank gauge  100  without an optical sensor, according to an embodiment. A conventional tank gauge  100  can be mounted on top of a liquid-filled tank (not shown). The conventional tank gauge can have a measurement vial  102  having measurement markings: an empty marking  112 , a ¼ full marking  110 , a ½ full marking  108 , a ¾ full marking  106 , and a full level marking  104  either drawn or etched on the measurement vial material, which can be glass or plastic. Inside the measurement vial  102  can be an indicator  114 , which can be used to determine the level of liquid in the tank by direct visualization. The indicator  114  can be connected to a stem  116  that passes through the tank wall  120  into the tank, the stem&#39;s  116  other end being attached to a buoyant float (not shown) that rises and falls based upon the liquid present in the tank. The conventional tank gauge  100  can be mounted to the tank wall  120  using a threaded bushing  118 , such that the conventional tank gauge  100  can be removed from the tank by unscrewing the conventional tank gauge  100  from the threaded bushing  118 . 
         [0027]      FIG. 2  is a perspective view of an optical sensor  122 , according to an embodiment. The optical sensor  122  can slide over the measurement vial (not shown), allowing the conventional tank gauge (not shown) to be read while simultaneously recording and transmitting the liquid level electronically. The optical sensor  122  can be secured to the conventional tank gauge using an optical sensor frame that has a lower mounting ring  124  and an upper mounting cap  126 , which are connected to one another using a plurality of vertical risers  128 . Each vertical riser  128  may have one or more marks  162  applied directly on, or below, a portion of the surface, for the primary purpose of visually identifying the line of sight between an emitter and detector. The marks  162  can be created by using compatible paint or adhesive labels. Alternatively, the marks  162  can be created by etching or uniquely shaping the riser  128  material. The lower mounting ring  124  can have one or more holes configured to accept one or more set screws  132 , which can be used to secure the optical sensor  122  to the conventional tank gauge. The lower mounting ring  124  can be tubular, and can have one or more flat faces that can allow the mounting of either the emitter circuit board  140  or the detector circuit board  142  by a board screw  144  such that the circuit boards  140 ,  142  are flush with the lower mounting ring  124 . 
         [0028]    The upper mounting cap  126  can have one or more holes configured to accept one or more set screws  132 , which can be used to secure the optical sensor  122  to the conventional tank gauge. The upper mounting cap  126  can be tubular, and can have one or more flat faces that can allow the mounting of either the emitter circuit board  140  or the detector circuit board  142  by a board screw  144  such that the circuit boards  140 ,  142  are flush with the upper mounting cap  126 . The upper mounting cap can include a countersunk chamber and hole located in the center, which can be configured to accept a height adjustment screw  130 . 
         [0029]    The one or more set screws  132  can be used to adjust the horizontal alignment of the optical sensor  122  on the conventional tank gauge  100  by screwing them further in or unscrewing them further out. The set screws  132  can have large heads and jut out from the optical sensor  122  for hand tightening. Alternatively, the set screws  132  can have standard screw heads and recess into a mounting ring or cap. 
         [0030]    The height adjustment screw  130  can be used to adjust the vertical alignment of the optical sensor  122  on the conventional tank gauge  100  by screwing in or out. The end of the height adjustment screw  130  can be flat, and can include a plate that touches the measurement vial (not shown) so as to prevent the measurement vial from breaking during an over-adjustment. In an embodiment, protective foam (not shown) can be adhered to the end of the height adjustment screw  130  or the optional plate to provide further protection. The other end of the height adjusted screw  130  can be a wide textured head configured to be adjusted by hand. The lower mounting ring  124 , upper mounting cap  126 , vertical risers  128 , height adjustment screw  130 , and set screws  132  can be made of metal, plastic, elastomer, or a combination thereof. 
         [0031]    The emitter circuit board  140  can have a plurality of photoemitters  152  attached to one side. The photoemitters  152  can generate photons at a pre-determined wavelength in the presence of a small electrical current. Each of the plurality of photoemitters  152  can require an emitter shroud (not shown) to create a narrow aperture for the photon beam, in order to provide a more accurate measurement. The emitter shroud can be created using heat shrink material, compatible paint, adhesive tape, or a prefabricated emitter housing. The emitter circuit board  140  can additionally have a wire harness  148  that can be used to hold the power and data cable bundle  146  used to provide power and data connection to the emitter circuit board  140 . The power and data cable bundle  146  can be attached to the wire harness  148  using a plug and a socket design at the harness header  150  such that the power and data cable bundle  146  can be manually detached if necessary. Alternately, the power and data cable bundle  146  can be hard-wired to the emitter circuit board  140 . 
         [0032]    The emitter circuit board  140  can have a visual status indicator  138 , which can be a single-color LED, configured to display the system states of the optical sensor. For example, the visual status indicator can illuminate when power is applied to the emitter board  140  and no system errors are detected; blink in a unique pattern when sending/receiving data; and blink in a second unique pattern if a predetermined error occurs. Alternatively, the visual status indicator  138  can be a multi-color LED, which can illuminate in two or different colors depending on the system state. For example, green when power is applied to the optical sensor and no system errors are detected; amber for sending and receiving data; and one or more unique red patterns for predetermined error codes. In each of the later cases the LED may be continuously on or blink to make further distinctions. 
         [0033]    The detector circuit board  142  can have a plurality of photodetectors  154  attached to one side. The photodetectors  154  can be phototransistors that generate a small electrical current in the presence of photons at a pre-determined wavelength. The position of the photodetectors  154  can correspond to the position of the photoemitters  152  on the emitter circuit board  140 . Each of the plurality of photodetectors  154  can require a detector shroud (not shown) to create a narrow aperture for the photon beam, in order to provide a more accurate measurement free from extraneous signals. The detector shroud can be created using heat shrink material, compatible paint, adhesive tape, or a prefabricated detector housing. 
         [0034]      FIG. 3  is an exploded view of an optical sensor with molded enclosures, according to an embodiment. The detector circuit board  142  can have a wire harness  148  that can be used to hold the power and data cable bundle  146  used to provide power and data connection to the detector circuit board  142 . The power and data cable bundle  146  can be attached to the wire harness  148  using a plug and a socket design at the harness header  150  such that the power and data cable bundle  146  can be manually detached if necessary. Alternately, the power and data cable bundle  146  can be hard-wired to the detector circuit board  142 . The detector circuit board  142  can have a wire port  158  that can interface with the main input/output cable  146  using a plug and socket design. A microcontroller  160  can read the analog output from each photodetectors  154  and convert the signal to a digital output using an analog to digital converter. The microcontroller  160  can produce a tank liquid level measurement based upon the digital output. The microcontroller  160  can also communicate the digital output, either directly or through a secondary device functioning as web client (not shown), to a web server (not shown) for transmission. The microcontroller  160  can also be configured to implement any other feature described herein. Either a microcontroller  160  can be used (which itself can function as a computer), or a microprocessor with the necessary components (ROM, RAM, input/output peripherals, etc.) can be used. 
         [0035]    In one alternative embodiment of the invention a separate microcontroller  160  is integrated directly into the optical sensor  122  to handle signal processing from each photodetector  154  prior to transferring compiled data to the supporting hardware that functions predominately as a web client. This compartmentalization approach allows a single web client design to interface with many variations of the proposed invention without requiring significant changes. 
         [0036]    Additionally, each photodetector  154  can have a corresponding detector indicator  156 , which can be an LED, which can illuminate when the photodetector  154  ceases to detect the photon beam emitted from the corresponding photoemitter  152 . Conversely, the detector indicator  156  can extinguish when the corresponding photodetector  154  detects the photon beam emitted from the corresponding photoemitter  152 . 
         [0037]    Molded enclosures  136  can be used to protect the one or both sides of an emitter circuit board  140  and the detector circuit board  142 . The molded enclosures  136  can be made of plastic and can be held in place by snaps or screws that fasten to the optical sensor framework. The molded enclosures  136  can have one or more indicator holes to allow the detector indicators  154  or visual status indicator  138  to remain visible. 
         [0038]    The detector circuit board  142  can have a visual status indicator  138 , which can be a single-color LED, configured to display the system states of the optical sensor. For example, the visual status indicator can illuminate when power is applied to the detector board  142  and no system errors are detected; blink in a unique pattern when sending/receiving data; and blink in a second unique pattern if a predetermined error occurs. Alternatively, the visual status indicator  138  can be a multi-color LED, which can illuminate in two or different colors depending on the system state. For example, green when power is applied to the optical sensor and no system errors are detected; amber for sending and receiving data; and one or more unique red patterns for predetermined error codes. In each of the later cases the LED may be continuously on or blink to make further distinctions. 
         [0039]      FIG. 4A  is a cross section view of a conventional tank gauge with an optical sensor in the process of adjustment, according to an embodiment. In this view, the optical sensor  122  is set on the conventional tank gauge  100 , with the photoemitters  152  and photodetectors  154  aligned below the measurement markings  104 ,  106 ,  108 ,  110 . To raise the vertical position of the optical sensor  122 , the user can loosen the set screws  132  located on the lower mounting ring  124  and the upper mounting cap  126 . The user can then rotate the height adjustment screw  130  such that the height adjustment screw  130  lowers into the upper mounting cap  124 . 
         [0040]      FIG. 4B  is a cross section view of a conventional tank gauge with an optical sensor in the process of adjustment, according to an embodiment. In this view, the optical sensor  122  is set on the conventional tank gauge  100 , with the photoemitters  152  and photodetectors  154  aligned above the measurement markings  104 ,  106 ,  108 ,  110 . 
         [0041]      FIG. 5  is a perspective view of an optical sensor  122 , according to an alternate embodiment. One or more sliders  134  can be used to maintain parallel alignment between the conventional tank gauge  100  and the optical sensor  122 . The sliders  134  can be mounted to the vertical risers  128  either by an embedded hole or a snap fastening. The sliders  134  can conform to the shape of the measurement vial  102 . Alternatively, the sliders  134  can be circular or some other geometric shape. The sliders  134  can be raised or lowered along the vertical risers  128  in order to most effectively maintain parallel alignment between the measurement vial  102  and the optical sensor  122 . A slider  134  can be made of metal, plastic, elastomer, or a combination thereof. 
         [0042]      FIG. 6  is an exploded view of an optical sensor with molded enclosures, according to an alternate embodiment. The addition of the sliders  134  does not affect the placement of any other element in the alternate embodiment. 
         [0043]      FIG. 7  is an example schematic diagram of a circuit implementing an optical sensor, according to an embodiment. The schematic diagram is one example of an implementation, however it can be appreciated that numerous other approaches can be taken as well. 
         [0044]      FIG. 8  is an example schematic diagram of a circuit implementing an optical sensor, according to an embodiment. The schematic diagram is one example of an implementation, however it can be appreciated that numerous other approaches can be taken as well. 
         [0045]      FIG. 9  is a block diagram illustrating the functions of an optical sensor, according to an embodiment. The photoemitters  152  and photodetectors  154  can be powered by a regulated DC power supply  900 . The photodetectors  154  can produce an analog data output  901 , which is dependent on the state of the photodetectors  154 . The analog data output  901  can be channeled into a digital output  903  by using an analog to digital converter  902 , which can be integrated with the microcontroller  160 . The microcontroller  160  can feed the digital output  903 , either directly, or through a secondary device functioning as an embedded server on a local network or a web client, into a network connection  904 , which can be wireless or wired, which can route to a web server  906 . The network connection  904  can include a local area network. Once the digital output  903  is received by the web server  906  it can be analyzed and stored in a database  908 . If the web server  906  determines particular data from a sensor meets certain criteria an automated message can be communicated to a user as a text message and/or an email message sent to a computerized device  907 . The web server  906  can also host a secure web site to provide each unique user with access to various online services, such as but not limited to: 1) displaying graphics and text that represent the current status of the optical sensor  122 ; 2) turn automated messaging on/off; and 3) change the interval between client-server communications. Access to the web server  906  can be accomplished using nothing more than a web browser on numerous types of mobile or stationary devices  907  (e.g. computer, tablet, smartphone, etc.) with Internet access. Alternatively, access to the web server  906  can be accomplished using an application developed for various operating systems. 
         [0046]      FIG. 10  is a perspective view of an optical sensor, according to an alternate embodiment. The alternate embodiment of the optical sensor  200  utilizes the same emitter/detector principle as the primary embodiment, but can be placed in a frame that allows for placement on conventional tank gauges with varying sizes. The optical sensor  200  can have a plurality of emitter blocks  136 , each block having a photoemitter  152 . The emitter blocks  136  can be held in a vertical alignment by an emitter wire frame  128 , which can run through each emitter block  136  to maintain position. Maintaining the vertical position of an emitter block  136  can be done using one or more set screws (not shown) that press against an emitter wire frame  128 ; and/or allowing an emitter block  136  to engage teeth  210  spaced along an emitter wire frame  128  that may or may not include location marks, such as numbers or colors, at various intervals. The emitter blocks  136  can be connected together with an emitter wire strip  212 , which can be used to transmit data and power to the photoemitters  152  and the microcontroller (not shown). The emitter blocks  136  can be bounded by an emitter top piece  204  and an emitter base  202 , which can also be connected to the emitter wire frame  128 . 
         [0047]    The emitter base  202  can have a visual status indicator  138 , which can be a single-color LED, configured to display the system states of the optical sensor. For example, the visual status indicator can illuminate when power is applied to the emitter base  202  and no system errors are detected; blink in a unique pattern when sending/receiving data; and blink in a second unique pattern if a predetermined error occurs. Alternatively, the visual status indicator  138  can be a multi-color LED, which can illuminate in two or different colors depending on the system state. For example, green when power is applied to the optical sensor and no system errors are detected; amber for sending and receiving data; and one or more unique red patterns for predetermined error codes. In each of the later cases the LED may be continuously on or blink to make further distinctions. 
         [0048]    The optical sensor  200  can have a plurality of detector blocks  137 , each block having a photodetector (not shown). The detector blocks  137  can be held in a vertical alignment by a detector wire frame  129 , which can run through each detector block  137  to maintain position. Maintaining the vertical position of a detector block  137  can be done using one or more set screws (not shown) that press against a detector wire frame  129 ; and/or allowing a detector block  137  to engage teeth  210  spaced along a detector wire frame  129  that may or may not include location marks, such as numbers or colors, at various intervals. The detector blocks  137  can be positioned such that a detector block  137  is aligned with an emitter block  136 . The detector blocks  137  can be connected together with a detector wire strip  213 , which can be used to transmit data and power to the photodetectors (not shown) and the microcontroller (not shown). The detector blocks  137  can be bounded by a detector top piece  205  and a detector base  206 , which can also be connected to the detector wire frame  129 . Each of the detector blocks  137  can have an indicator  156 , which can be an LED, configured to illuminate when the photodetector ceases to detect the beam created from the corresponding photoemitter, and extinguish when the photodetector detects the beam created from the corresponding photoemitter. 
         [0049]    The detector base  206  can have a visual status indicator  138 , which can be a single-color LED, configured to display the system states of the optical sensor. For example, the visual status indicator can illuminate when power is applied to the detector base  206  and no system errors are detected; blink in a unique pattern when sending/receiving data; and blink in a second unique pattern if a predetermined error occurs. Alternatively, the visual status indicator  138  can be a multi-color LED, which can illuminate in two or different colors depending on the system state. For example, green when power is applied to the optical sensor and no system errors are detected; amber for sending and receiving data; and one or more unique red patterns for predetermined error codes. In each of the later cases the LED may be continuously on or blink to make further distinctions. 
         [0050]    The emitter top piece  204  and the detector top piece  205  can be connected by one or more top springs  214 , such that a cylindrical object can be inserted in between the emitter top piece  204  and the detector top piece  205 , and be held in position through the top springs  214 . Each end of a top spring  214  can be attached to opposing points  216  on an emitter top piece  204  and detector top piece  205  using a connection method that is permanent or detachable. The top spring  214  can be made of metal, plastic, natural or synthetic fibers, or a combination thereof. Alternatively, the emitter top piece  204  and the detector top piece  205  can be connected by one or more top springs  214  that have rigid or semi-rigid properties. Both the emitter top piece  204  and the detector top piece  205  can have top piece notches  208  to further conform to the conventional tank gauge. The top piece notches  208  can be comprised of one or more materials with properties that limit or restrict movement of an emitter top piece  204  and detector top piece  205  when pressed against a vial  102 . The emitter base  202  and the detector base  206  can be connected by one or more base springs  215 , such that a cylindrical object can be inserted in between the emitter base  202  and the detector base  206 , and be held in position through the base springs  215 . Each end of a base spring  215  can be attached to opposing points  216  on an emitter base piece  202  and detector base piece  206  using a connection method that is permanent or detachable. The base spring  215  can be made of metal, plastic, natural or synthetic fibers, or a combination thereof. Alternatively, the emitter base  202  and the detector base  206  can be connected by one or more base springs  215  that have rigid or semi-rigid properties. Both the emitter base  202  and the detector base  206  can have base notches  209  to further conform to the conventional tank gauge. The base notches  209  can be comprised of one or more materials with properties that limit or restrict movement of an emitter base  202  and detector base  206  when pressed against a vial  102 . A data cable  146  can attach to either the detector base  206  or the emitter base  202 , and can be used to transmit power and data to and from the optical sensor  200 . A connection cable  148  can attach to the detector base  206  and the emitter base  202 , and can be used to transmit power and data between the emitter blocks  136  and the detector blocks  137 . 
         [0051]      FIG. 11  is a top view of an optical sensor attached to a small conventional tank gauge, according to an alternate embodiment. In a small conventional tank gauge, the diameter of the measurement vial  102  is slightly larger than the diameter of the indicator  114 . Due to the smaller size, the top springs  214  deform only slightly to admit the measurement vial  102  in between the detector top piece  205  and the emitter top piece  204 . The connection cable  148 , being flexible, can curve more dramatically to accommodate the smaller separation between the emitters and the detectors. 
         [0052]      FIG. 12  is a top view of an optical sensor attached to a large conventional tank gauge, according to an alternate embodiment. In a large conventional tank gauge, the diameter of the measurement vial  102  is significantly larger than the diameter of the indicator  114 . Due to the larger size, the top springs  214  deform significantly to admit the measurement vial  102  in between the detector top piece  205  and the emitter top piece  204 . The connection cable  148 , being flexible, straightens to accommodate the larger separation between the emitters and the detectors. 
         [0053]    Although the present device has been described in terms of exemplary embodiments, none is limited thereto. Rather, the appended claims should be construed broadly to include other variants and embodiments of the present apparatus, which may be made by those skilled in the art without departing from the scope and range of equivalents of either the apparatus or the methods for using such an apparatus.