Abstract:
A system and method for providing a fork sensor including an emitter, a receiver, and at least one lens assembly wherein the width of the effective beam does not depend upon the size of the emitter or the receiver. One aspect of the present invention is a method for detecting or counting the number of objects interrupting the effective beam of the fork sensor. Another aspect of the present invention is a method for measuring the dimensions of objects using the fork sensor.

Description:
TECHNICAL FIELD 
   The present invention relates to photoelectric sensors, and more specifically to a self-contained photoelectric sensor having a wide effective beam. 
   BACKGROUND 
   Photoelectric sensors debuted as throughbeam devices composed of lights and reflectors. Over the years, these sensors have developed into a multitude of designs, each used for a variety of purposes. One of these designs is the self-contained throughbeam, sometimes called a fork sensor. This sensor style, typically configured in a block letter C-shape, sends an electromagnetic signal (e.g., a beam of visible light, a laser beam, etc.) across from one arm of the sensor to another. Self-contained fork sensors can be used for a variety of applications, such as in production lines. For example, the sensors can be used to detect the presence or absence of items passing through the beam along a conveyor. 
     FIG. 1  illustrates a schematic of a fork sensor  100  currently used in industry. Housing  110  of the fork sensor  100  includes a first and second arm  101 ,  102  extending from a base  105 . The first arm  101  includes an emitter  107  at a distal end  103 . A second arm  102  includes a receiver  108  at a distal end  104 . The emitter  107  is connected to a power source (not shown) and the receiver  108  is connected to a signal processing assembly (not shown). The emitter  107  is aligned with the receiver  108  such that a beam of light transmitted by the emitter  107  is received by the receiver  108  and converted into an electrical signal output. Placing a sufficiently opaque object between the emitter  107  and the receiver  108  interrupts a portion of the transmitted light before it reaches the receiver  108 , thereby changing the signal output. 
   The beam of light has an effective width W 1 , which is defined by the amount of light transmitted by the emitter  107  that is also received by the receiver  108 . The magnitude of the effective width W 1  depends on the size of the emitter  107  and the receiver  108 . Generally, both the emitter  107  and the receiver  108  are on the order of a couple millimeters wide. Therefore, the effective width W 1  of the beam is only on the order of a couple millimeters. 
   In order for an object to interrupt the beam as it passes between the emitter  107  and the receiver  108 , at least a portion of the object must pass within those few millimeters. Therefore, movement of smaller objects through the fork sensor  100  must be accurately controlled. 
   SUMMARY 
   In general terms, the present invention is a system and method for providing a self-contained fork sensor having a wide effective beam. 
   One aspect of the present invention includes a method for providing a wide effective beam in a self-contained fork sensor. The method includes transmitting a first electromagnetic (EM) beam to a lens assembly, the first EM beam having a first width. The method further includes modifying the first EM beam to create a second EM beam substantially perpendicular to the first EM beam, the second EM beam having a width substantially wider than the first width. The method still further includes transmitting the second EM beam over a distance to the lens assembly, and modifying the second EM beam to create a third EM beam substantially perpendicular to the second EM beam. The second EM beam has a width substantially wider than the third EM beam. 
   In some embodiments, the lens assembly is a single lens assembly. In these embodiments, transmitting the second EM beam over a distance to the lens assembly includes transmitting the second EM beam to a reflective target and transmitting the second EM beam from the reflective target back to the lens assembly. 
   In some other embodiments, the lens assembly includes a first and second lens assembly, and transmitting the first EM beam to the lens assembly includes transmitting the first EM beam to the first lens assembly. Transmitting the second EM beam to the lens assembly includes transmitting the second EM beam to the second lens assembly. 
   In one example embodiment, a self-contained fork sensor includes an emitter, a lens assembly, a target, and a receiver. The lens assembly includes a first surface and a second surface. The first surface is configured to receive a first beam of light from the emitter and to transmit a final beam of light to the receiver. The second surface is configured to transmit a second beam of light to the target and to receive a third beam of light from the target. The second and third beams have widths substantially wider than the first and final beams. The receiver receives the final beam of light from the lens assembly and generates an output signal based on the final beam. 
   In another example embodiment, a self-contained fork sensor includes an emitter, a first lens assembly, a second lens assembly, and a receiver. The emitter generates a first beam of light to the first lens assembly. The first lens assembly receives the first beam of light and transmits a second beam of light to the second lens assembly. The second lens assembly receives the second beam of light and transmits a third beam of light to the receiver. The receiver receives the third beam of light and generates an output signal. The second beam of light has a width substantially greater than either the first or the third beam of light. 
   Embodiments of the present invention can be used to detect the presence of objects, to count objects in gravity based packaging, or to measure the dimensions of an object passing anywhere along the length of the lens assemblies. 
   One aspect of the present invention is a method for counting the number of objects passing between the effective beam of the fork sensor. The method includes taking a base reading of an output signal generated by the receiver. The method further includes calibrating the fork sensor and measuring the changes in the output signal resulting from objects interfering with the effective beam of the fork sensor. 
   Yet another aspect of the present invention is a method for measuring the dimensions of objects using a fork sensor. The method includes taking a base reading and then placing an object within the effective beam of the fork sensor so that the object blocks at least a portion of the light beam. The method further includes measuring the changes in the output signal generated by the receiver based on the changes in the amount of the light reaching the receiver. 
   In one embodiment of the present invention, a fork sensor includes lens assemblies which are unitary in construction. In another embodiment of the present invention, each lens assembly includes a first lens and a redirecting feature. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a fork sensor as known in the art; 
       FIG. 2  illustrates a fork sensor according to one embodiment of the present disclosure; 
       FIG. 3  illustrates a path and corresponding effective width of a light beam as it propagates through a fork sensor assembly according to one embodiment of the present disclosure; 
       FIG. 4  illustrates an alternative embodiment of a fork sensor assembly; 
       FIG. 5  illustrates a single-piece lens for use in a fork sensor according to one embodiment of the present invention; 
       FIG. 6  illustrates a portion of the single-piece lens of  FIG. 5 ; 
       FIG. 7  illustrates a lens structure for use in a fork sensor according to another embodiment of the present invention; 
       FIG. 8   a  illustrates the transmission of a light beam between a first lens assembly and a second lens assembly of a fork sensor according to another embodiment of the present invention; 
       FIG. 8   b  illustrates the effect on the light beam transmission of  FIG. 8   a  when an object is placed between the first and second lens assemblies; 
       FIG. 9  is a flow chart illustrating an example operational flow for detecting objects using a wide beam fork sensor; and 
       FIG. 10  is a flow chart illustrating an example operational flow for measuring the width of an object using a wide beam fork sensor. 
   

   DETAILED DESCRIPTION 
   Various embodiments of the present invention will be described in detail with reference to the drawings, wherein like reference numerals represent like parts and assemblies throughout the several views. Reference to various embodiments does not limit the scope of the invention, which is limited only by the scope of the claims attached hereto. Additionally, any examples set forth in this specification are not intended to be limiting and merely set forth some of the many possible embodiments for the claimed invention. 
   Referring now to  FIGS. 2-4 , a wide beam fork sensor includes a light emitter, a light receiver, and at least one lens assembly extending substantially the length of one arm of the fork sensor. One end of each lens assembly is configured to transmit or receive a first beam having an effective beam width extending substantially along the length of the lens assembly. Another end of each lens assembly is configured to transmit or receive a second beam having an effective beam width extending substantially less than the effective beam width of the first beam. 
   Referring now to  FIG. 2 , in some embodiments, the light emitter and light receiver are oriented towards a first lens assembly extending along a first arm of the fork sensor and a second lens assembly extending along a second arm of the fork sensor, respectively.  FIG. 2  illustrates a fork sensor  200  including a housing  220  having a first and second arm  221 ,  222  extending from a base  225 . In some embodiments, the first and second arms  221 ,  222  extend intermediate 5 mm and 50 mm. However, the length of the first and second arms  221 ,  222  is limited only by the dimensions of the desired overall fork sensor  200 . In some embodiments, the first and second arms  221 ,  222  are spaced intermediate 5 mm and 100 mm apart. However, the distance intermediate the first and second arms  221 ,  222  is also limited only by the dimensions of the desired overall fork sensor  200 . 
   The base  225  includes an emitter  207  at one end  213  and a receiver  208  at another end  214 . However, the embodiment is not limited by the location of the emitter  207  and receiver  208  and these components can be located in other areas of the fork sensor  200  without deviating from the spirit of the present disclosure. 
   In one embodiment, the emitter  207  is positioned and oriented to emit an EM (e.g., light) beam along the length of the first lens assembly  201 . The frequency of the transmitted light is limited only by the ability of the receiver  208  to accurately sense the light. According to one embodiment, the emitter  207  is an LED that emits visible light. According to another embodiment, the emitter  207  emits infrared light. According to yet another embodiment, the emitter  207  generates ultraviolet light. 
   The receiver  208  is positioned and oriented to receive the transmitted light. In one embodiment, the receiver is a semiconductor photodiode. However, the embodiment is not limited to a photodiode and any suitable photosensor can be used. 
   In one embodiment, a power source  209  is also included within the base  225 . The emitter  207  is electrically connected to the power source  209 . According to another embodiment, the power source  209  is external to the housing  220  and is electrically connected to a power supply line (not shown) leading into the housing  220 . In this embodiment, the power supply line is electrically coupled to the emitter  207 . Examples of power sources include batteries, voltage generators, solar cells and the like. 
   In one embodiment, a signal processing assembly  211  is included within the base  225 . According to this embodiment, the receiver  208  is electrically connected to the signal processing assembly  211 . In another embodiment, the signal processing assembly  211  is external to the housing  220  and is electrically connected to a signal transmission line (not shown) leading out of the housing  220 . In this embodiment, the signal transmission line is connected to the receiver  208 . 
   In one embodiment, a first and second attachment hole  215 ,  216  are defined by the base  225 . These holes  215 ,  216  enable the fork sensor  200  to be attached to a surface using fasteners such as screws, nails, pegs, or the like. However, the embodiment is not limited to these fasteners and any suitable fastener can be used, such as a bonding material or the like. 
   According to one embodiment of the fork sensor  200 , the first arm  221  includes a first lens assembly  201  and the second arm  222  includes a second lens assembly  202 . When power is supplied to the emitter  207  from the power source  209 , the emitter  207  emits a photon beam towards the first lens assembly  201 . The first lens assembly  201  is arranged and configured to direct (e.g., or reflect, or refract) the light beam towards the second lens assembly  202 . The second lens assembly  202  is arranged and configured to receive and focus the light beam onto the receiver  208 . The receiver  208  transforms the received light beam into an electrical signal, which is then output to the signal processing assembly  211 . The path followed by the light beam will be explained in more detail herein with respect to  FIG. 3 . 
   Still referring to  FIG. 2 , each lens assembly  201 ,  202  includes a first surface  203 ,  204  extending substantially along the length of the respective arms  221 ,  222 . Each lens assembly  201 ,  202  further includes a second surface  205 ,  206  extending along the width of the respective arms  221 ,  222 . The first lens surface  203 ,  204  of each lens assembly  201 ,  202  is substantially perpendicular to the respective second lens surface  205 ,  206 . The first lens assembly  201  is configured so that light received at the second lens surface  205  of the first lens assembly  201  will be directed through the first lens surface  203  of the lens assembly  201  towards the second lens assembly  202 . Example lens surface  203 ,  205  configurations include a flat surface and a curved surface. The second lens assembly  202  is configured so that light received at the first lens surface  204  will be directed through the second lens surface  206  and towards the receiver  208 . Example lens surface  204 ,  206  configurations include a flat surface and a curved surface. 
   Each arm  221 ,  222  of the fork sensor  200  provides an open section, or window,  231 ,  232 , respectively, through which the light propagating between the two arms  221 ,  222  enters and exits the housing  220 . Each opening  231 ,  232  extends substantially along the length of the respective arm  221 ,  222 . According to one embodiment, the openings  231 ,  232  include a slit provided by the housing  220 . According to another embodiment, the openings  231 ,  232  include a piece of glass, plastic, or other such transparent material allowing light to pass through relatively unaffected. The open sections  231 ,  232  are generally defined by the planar lens surface  203 ,  204 . However, the embodiment is not limited to the above dimensions and any suitable dimension can be used. 
     FIG. 3  illustrates a schematic depicting a sensor assembly according to one embodiment of the present disclosure. The sensor assembly  300  includes a first lens assembly  310  and a second lens assembly  320 . The first lens assembly  310 , which is depicted in dashed lines, includes a first lens  302  and a second lens  303 . The second lens assembly  320 , which is also depicted in dashed lines, includes a first lens  304  and a second lens  305 . The sensor assembly  300  further includes an emitter  307  oriented towards the first lens  302  of the first lens assembly  310  and a receiver  308  oriented towards the second lens  305  of the second lens assembly  320 . 
   The emitter  307  transmits a beam of light along a path B in the direction of the first lens assembly  310 . The beam of light has a width W 2  upon leaving the emitter  307 . The beam enters the first lens assembly  310  at the first lens  302 . The beam has a beam width W 3  when it reaches the first lens  302 . In one embodiment, the beam of light diverges before it reaches the first lens  302  of the first lens assembly  310 . In this case, W 3 &gt;W 2 . In another embodiment, the beam of light does not diverge while traveling towards the first lens  302 . In this case, W 3 =W 2 . In yet another embodiment, the beam converges as it travels towards the first lens assembly  310  such that W 3 &lt;W 2 . 
   The light beam propagates through the first lens assembly  310  until it reaches the second lens  303 . The beam exits from the second lens  303  of the first lens assembly  310  and is transmitted along a path C towards the second lens assembly  320 . The path C extends between the first and second lens assemblies  310 ,  320 . Generally, the length of the second lens  303  of the first lens assembly  310  defines the width W 4  of the transmitted light beam along a path C such that W 4 &gt;W 2 . In one possible embodiment, path C has a width W 4  of 33 millimeters. However, the invention is not limited to this width and any suitable width can be used. 
   Upon reaching the second lens assembly  320 , the light beam passes through the first lens  304  and is directed towards the second lens  305 . The light beam has a width W 5  as it passes through the second lens  305  and travels along a path D to the receiver  308 . Generally, the width W 5  of the beam exiting the second lens assembly  320  is less than the width W 4  of the beam entering the assembly  320 . Finally, the light beam is received at the receiver  308 , which has a width W 6 . The width W 6  of the receiver is generally less than the width W 4  of the path C between the first and second light assemblies  310 ,  320 . In one embodiment, the width W 6  of the receiver  308  is on the same order as the width W 2  of the emitter  307 . However, the invention is not limited to this width relationship and the receiver  308  can be any suitable width. 
   Referring now to  FIG. 4 , in some other embodiments, a fork sensor includes only one arm.  FIG. 4  illustrates a retro-reflective fork sensor  400  including a housing  420  having an arm  421  extending from a base  425 . The base  425  includes an emitter  407  having a width W 2  and a receiver  408  having a width W 6 . The arm  421  includes at least one lens assembly  410 . Each lens assembly  410  is arranged and configured to transmit light to a target  430 , the light having an effective width W 4 , which is substantially wider than the widths W 2 , W 6  of the emitter and receiver  407 ,  408 . 
   In some embodiments, the target  430  is external of the fork sensor housing  420 . In other embodiments, the target  430  is contained within a second arm (e.g., as shown in  FIG. 2 , element  222 ) of the fork sensor housing  420 . The target  430  is arranged and configured to reflect a substantial portion of the light received from the lens assembly  410  back to the lens assembly  410 . Various example embodiments of the target  430  are formed from reflective prisms and spheres. 
   In some embodiments, the arm  421  includes only one lens assembly  410 . The emitter  407  is oriented to transmit light to the lens assembly  410  and the receiver is oriented to receive light from the lens assembly  410 . In these embodiments, the base  425  further includes a beam splitter  435  arranged and configured to transmit light received from the emitter  407  to the lens assembly  410 , but to reflect light received from the lens assembly  410  to the receiver  408 . 
   In some other embodiments, the arm  421  includes a first and second lens assembly  410   a ,  410   b , respectively. The first and second lens assemblies  410   a ,  410   b  are arranged and configured to transmit and receive light without interfering with one another. In one example embodiment, the first lens assembly  410   a  is positioned on top of the second lens assembly  410   b . In some embodiments, the base  425  includes an emitter  407  positioned and oriented to transmit light to the first lens assembly  410   a  and a receiver  408  positioned and oriented to receive light from the second lens assembly  410   b . A beam of light travels from the emitter  408  to the first lens assembly  410   a , which transmits the light to the target  430 . The target  430  reflects the light to the second lens assembly  410   b , which transmits the light to the receiver  408 . 
   Similar to the fork sensor depicted in  FIG. 2 , some embodiments of the base  425  of the fork sensor  400  include a power source and a signal processing assembly (not shown). In other embodiments, the base  425  includes power supply lines and signal transmission lines (not shown). Generally, any suitable means may be used to power the emitter  407  or to analyze a signal generated by the receiver  408  without deviating from the spirit and scope of this disclosure. 
     FIGS. 5-7  illustrate different possible embodiments of the lens assemblies  310 ,  410 .  FIG. 5  illustrates one possible embodiment of a lens assembly  310 ,  410  that includes a single-piece lens  500 . An emitter  550  emits a beam of light towards a single-piece lens  500 . The single-piece lens  500  includes a first surface  501  through which light from the emitter  550  enters the single-piece lens  500 , a second surface  502  through which the light exits the single-piece lens  500 , and a third surface  503  for receiving the light from the first surface  501  and transmitting the light to the second surface  502 . The first surface  501 , the second surface  502 , and the third surface  503  are all formed from a single piece of material. Generally, the first surface  501  is oriented substantially perpendicular to the second surface  502 . However, the invention is not limited to this orientation and any suitable orientation may be used. 
   The first surface  501  is arranged and configured so that light generated by the emitter  550  will propagate in a generally straight line after passing through it. In one embodiment, the first surface  501  is convexly shaped to focus a diverging beam of light into a non-diverging beam. In another embodiment, the first surface  501  is flat, enabling a non-diverging beam of light to pass through unaltered. In yet another embodiment, the first surface  501  is concavely shaped to refract a converging beam of light into a straight, non-converging beam. Generally, the width SW 1  of the first surface  501  ranges between one and twenty millimeters. Typically, the width SW 1  of the first surface  501  is 10 millimeters. However, the embodiment is not limited to these dimensions and any suitable dimensions can be used. 
   The second surface  502  is arranged so that light  541  exiting through the surface  502  is shaped substantially like beam spot  540 . Beam spot  440  illustrates one pattern of light; however, the invention is not limited to the pattern formed by beam spot  540 , and any suitable pattern may be used, such as square, oval or the like. Generally, the height H 1  of the second surface  502  ranges from 1 mm to 5 mm as illustrated in the beam spot  540 . In one embodiment, the width SW 2  of the second surface  502  is much greater than the width SW 1  of the first surface  501 . In another embodiment, the width SW 2  of the second surface  502  is about the same as the width SW 1  of the first surface  501 . Generally, the width SW 2  of the second surface  502  ranges between 10 and 50 millimeters. Typically, the width SW 2  of the second surface  502  is 33 millimeters. 
   The third surface  503  of the single-piece lens  500  is arranged to reflect light from the first surface  501  to the second surface  502 . Generally, the width SW 3  of the third surface  503  ranges between 15 and 50 millimeters. Typically, the width SW 3  of the third surface is about 38 millimeters. However, the embodiment is not limited to these dimensions, and any suitable dimensions can be used. Generally, an area is formed by the first surface  501 , second surface  502 , and third surface  503 , in which the second and third surfaces  502 ,  503  are defined by an angle Ø. Typically, the angle Ø between the second surface  502  and the third surface  503  ranges between 5° and 45°. In one possible embodiment, the angle Ø is about 15°. However, the embodiment is not limited to these dimensions and any suitable dimensions can be used. 
   According to one embodiment, the single-piece lens  500  is formed from an acrylic material. One example of such a material is Polymethyl methacrylate (PMMA). According to another embodiment, the single-piece lens  500  is formed from glass. According to yet another embodiment, the single-piece lens  500  is formed from plastic, fiberglass, plexi-glass, or the like. However, the invention is not limited to these materials and any suitable material can be used. 
     FIG. 6  illustrates one embodiment of a portion  600  of the third surface  503  of the single-piece lens  500  as illustrated in  FIG. 5 . The portion  600  of the reflective surface  503  includes a series of undulations (e.g., ridges)  605 . The undulations  605  are arranged and configured to reflect a beam of light entering through the first surface  501  out towards the second surface  502 . The undulations  605  are further arranged and configured to reflect towards the second surface  502  a beam of light having a larger width than the beam propagating from the first surface  501 . 
   These undulations  605  are composed of a first surface  606  and second surface  607 . In one embodiment, the first surface  606  and second surface  607  are flat and oriented generally perpendicular from each other. In another embodiment, the first and second flat surfaces  606 ,  607 , are angled obliquely from each other. In yet another embodiment, the undulations  605  are composed of a series of Gaussian shaped waves (not shown) having first and second halves  606 ,  607 . In still yet another embodiment, the undulations  605  are composed of first and second curved surfaces (not shown) angled either orthogonally or obliquely from one another. 
   In one embodiment, light rays entering through the first surface  501  propagate through the single-piece lens  500  and reach the first surface  606 . Surface  606  is arranged and configured to reflect the light rays towards the second surface  607  of the undulation  605 . Surface  607  is arranged and configured to reflect the light waves towards the second surface  502 . Generally, each undulation surface  606 ,  607  ranges between 0.1 millimeter and 0.7 millimeter. Typically, each undulation  605  extends over a length of 0.25 millimeter. However, the invention is not limited to undulations of this size and any suitable undulation size may be used. 
     FIG. 7  illustrates one possible embodiment of a lens assembly  310 ,  410  that includes a lens structure  700 . An emitter  750  emits a beam of light towards the lens structure  700 . The lens structure  700  includes a first lens  705  and a redirecting feature  710 . Light generated by the emitter  750  propagates to the first lens  705 , which directs the light towards the path modification feature  710 . The redirecting feature  710  bends (e.g., or redirects) the light so that it propagates in a non-diverging, wide beam along a direction F towards either a target (as illustrated in  FIG. 4 , element  430 ) or a second lens assembly (as illustrated in  FIG. 3 , element  320 ). 
   According to one embodiment, the first lens  705  is arranged and configured to modify (e.g., refract) diverging light from the emitter  750  into a non-diverging beam  713 . According to another embodiment, the first lens  705  is arranged to modify converging light into a non-diverging beam. In yet another embodiment, the first lens  705  is arranged and configured to enable a non-diverging light beam to pass unaltered. In one embodiment, the first lens  705  is not connected to the redirecting feature  710 . In another embodiment, the first lens  705  is connected to the redirecting feature  710 . 
   In some embodiments, the redirecting feature  710  includes a series of peaks (e.g., ridges)  712 . Each peak  712  has an angled surface  714  oriented towards the first lens  705 . In one embodiment, the first lens  705  is angled obliquely in relation to the redirecting feature  710 . Light rays passing through the first lens  705  are directed towards the angled surface  714  of each peak  712 . Upon reaching the angled surface  714 , the light rays are refracted along a path in the direction F to form a beam  716  of light having a width W 6 . The angled surface  714  is arranged so that light  716  is shaped substantially like beam spot  740 . Beam spot  740  illustrates one pattern of light; however, the invention is not limited to the pattern formed by beam spot  740 , and any suitable pattern may be used, such as square, oval or the like. 
   In one embodiment, the redirecting feature  710  further includes a dust shield  715  for keeping dust and other such particles off of the redirecting feature  710 . Interference from dust or other such particles on the surface of the redirecting feature  710  can cause the light to bend at an undesired angle, which would cause the resulting beam to diverge or converge rather than propagate in a straight line. According to one embodiment, the dust shield  715  is spaced from the redirecting feature  710 , but is still contained within the housing of the fork sensor (see, e.g.,  FIG. 2 , element  220  and  FIG. 4 , element  420 ). According to another embodiment, the housing of the fork sensor defines the dust shield  715 . 
   Referring now to  FIGS. 8-10 , some example applications for a wide beam fork sensor are illustrated.  FIGS. 8   a  and  8   b  illustrate embodiments of fork sensors  800   a ,  800   b  utilizing a wide effective beam to detect, count, and measure objects  850 .  FIG. 8   a  illustrates an unobstructed light beam traveling between a first lens assembly  805  and a second lens assembly  810  of the fork sensor  800   a . In other embodiments, the fork sensors  800   a ,  800   b  are configured similar to fork sensor  400  depicted in  FIG. 4  and have only one lens assembly  805 . The lens assemblies  805 ,  810  have a beam width of Q.  FIG. 8   b  illustrates the effect on the light beam when an object  850  having a width O, such that Q≧O, is placed between the first and second lens assemblies  805 ,  810 . 
   Referring now to  FIG. 9 , embodiments of the fork sensor  800  are used in various industrial processes. In some embodiments, the fork sensor  800  is utilized to detect objects in a gravity-fed packaging process. In other embodiments, the fork sensor  800  is utilized to detect small parts ejected from a manufacturing process such as a metal stamping machine. In still some other embodiments, the fork sensor  800  is utilized to verify an assembly process such as sensing a cap on a small bottle.  FIG. 9  illustrates a flow chart depicting an operation flow  900  for detecting objects  850  using a wide beam fork sensor  800 . The process  900  will be described with reference to  FIGS. 8   a  and  8   b.    
   The process starts at module  905  and proceeds to setup operation  910 . Setup operation  910  includes providing a fork sensor  800  having a first and second wide lens assembly  805 ,  810 , an emitter  815 , and a receiver  820 . Power is supplied to the emitter  815  in powering operations  915 . Supplying power causes the emitter  815  to transmit a beam of light in the direction of the first lens assembly  805 . The beam of light is then transmitted from the first lens assembly  805  to the second lens assembly  810 , which transmits the beam to the receiver  820 . The receiver  820  is arranged to receive the beam and to convert the beam into an electrical signal output. 
   In a sensor calibration operation  920 , a first reading measuring the signal output from the receiver  820  is taken. The first reading represents the amount of light received when the light from the emitter  815  reaches the receiver  820  without interruption or diversion. Module  925  changes the flow of operations  900  based on whether objects  850  are being counted or merely detected. If objects  850  are being counted, then the sensor  800  is further calibrated in object calibrating operation  927 . This operation will be discussed in greater detail herein. If objects  850  are merely being detected, then the process proceeds directly to sensing operation  930 . 
   Sensing operation  930  includes dropping one or more objects  850  through the beam propagating between the first and second lens assemblies  805 ,  810  of the fork sensor  800 . The objects pass through the beam extending between the first and second lens assemblies  805 ,  810 . When one of the objects is located in the path of the beam, at least some of the light from the beam is blocked from reaching the second lens assembly  810 . Blocking at least a portion of the light causes the signal output of the receiver  820  to decrease. This decrease is detected in processing operation  935 . The process  900  ends at module  940 . 
   If the process  900  had proceeded to object calibrating operation  927 , then the fork sensor  800  would have been further calibrated to measure the change in signal output from the receiver  820  due to a single object  850  passing through the beam of light. This operation assumes that objects  850  of generally the same dimension will be passing through the beam at generally the same velocity. Once object calibrating operation  927  is completed, then the process proceeds to sensing operation  930 . The quantity of object  850  passing through the beam can then be determined using methods known in the art in processing operation  935  from the information gathered in sensing operation  930 . 
   Pills being packaged using a gravity-fed packaging process, machine parts being transported by a conveyer belt, and small parts being ejected from a manufacturing process, are examples of objects  850  that can be detected and counted. However, the invention is not limited to the detection of these objects, and any object capable of breaking the beam, or a portion thereof, can be detected. 
   Referring now to  FIG. 10 , embodiments of the fork sensor  800  can also be used to measure various objects  850 . In one example embodiment, the fork sensor  800  measures the diameter of an extruded tube. In another example embodiment, the fork sensor  800  guides an edge of a web-based process, using analog or discrete outputs.  FIG. 10  illustrates a flow chart depicting an operational flow  1000  for measuring objects  850  using a fork sensor  800  having a wide effective beam. The process  1000  will be discussed with reference to  FIGS. 8   a  and  8   b.    
   The process starts at module  1005  and proceeds to setup operation  1010 . A fork sensor  800  having a first and second lens assembly  805 ,  810 , an emitter  815 , and a receiver  820  is provided in setup operation  1010 . The emitter  815  is arranged to transmit a beam of light when supplied with power. The receiver  820  is arranged to receive the beam of light and to convert the beam into an electrical signal output. The first and second lens assemblies  805 ,  810  extend along a substantial portion of the fork sensor  800 . At this stage, the area between the first and second lens assemblies  805 ,  810  is not obstructed by any objects  850 . 
   Power is supplied to the emitter  815  in powering operation  1015 . The power causes the emitter  815  to emit a beam of light  811  in the direction of the first lens assembly  805 , which transmits the light towards the second lens assembly  810  such that the beam passing between the assemblies  805 ,  810  has a width Q. The second lens assembly  810  transmits the light  813  towards the receiver  820 . Calibrating operation  1020  includes taking a first reading of the received signal output from the receiver  820 . The first reading represents the signal received when the beam of light passes between the two lens assemblies  805 ,  810  without interruption or divergence. 
   An object  850  having a width O is placed in the path of the light beam between the two lens assemblies  805 ,  810  in placement operation  1025 . Because the width Q of the light beam is greater than the width O of the object, only a portion of the light is blocked from reaching the second lens assembly  810 . In sensing operation  1030 , a second reading is taken of the received signal output from the receiver  820 . The difference between the first signal output and the second signal output is calculated in processing operation  1035 . This difference can be mathematically converted into a dimensional measurement using methods known in the art. The process  1000  ends at module  1040 . 
   The various embodiments described above are provided by way of illustration only and should not be construed to limit the invention. Those skilled in the art will readily recognize various modifications and changes that may be made to the present invention without following the example embodiments and applications illustrated and described herein, and without departing from the true spirit and scope of the present invention, which is set forth in the following claims.