Abstract:
A deposition system includes a system housing having a housing interior, a fixture transfer assembly having a generally sloped fixture transfer rail extending through the housing interior, a plurality of processing chambers connected by the fixture transfer rail, a controller interfacing with the processing chambers and at least one fixture carrier assembly carried by the fixture transfer rail and adapted to contain one substrate. The fixture carrier assembly travels along the fixture transfer rail under influence of gravity. A deposition method is also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of application Ser. No. 13/653,352, filed Oct. 16, 2012 and entitled VAPOR DEPOSITION SYSTEM AND METHOD, which application is incorporated by reference herein in its entirety and claims the benefit of U.S. provisional patent application No. 61/613,366, filed Mar. 20, 2012 and entitled VAPOR DEPOSITION SYSTEM AND METHOD, which application is incorporated by reference herein in its entirety; and this application is a continuation in part of U.S. Ser. No. 13/030,091, filed on Feb. 17, 2011 entitled “VAPOR DEPOSITION SYSTEM AND METHOD, which in turn claims the benefit of U.S. provisional application No. 61/338,949, filed Feb. 26, 2010 and entitled “FIXTURE TO SUSPEND OPHTHALMIC LENSES FOR CONCAVE AND CONVEX SIDE APPLICATIONS; U.S. provisional application No. 61/338,951, filed Feb. 26, 2010 and entitled “FIXTURE DEVICE FOR THE APPLICATION OF VAPOR DEPOSITION ON THE CONCAVE AND CONVEX SIDES OF AN OPHTHALMIC LENS WHILE ROTATING”; U.S. provisional application No. 61/343,668, filed May 3, 2010 and entitled “GRAVITY FED TRANSFER MECHANISM”; U.S. provisional application No. 61/343,669, filed May 3, 2010 and entitled “HYDROPHOBIC, OLEOPHOBIC OR SUPER HYDROPHOBIC APPLICATOR”; and U.S. provisional application No. 61/343,672, filed May 3, 2010 and entitled “FULLY AUTOMATED, IN-LINE, HIGH THROUGHPUT, LOW VOLUME, SIMULTANEOUS AND NON-SIMULTANEOUS PROCESS, HIGH AND LOW VACUUM, PHYSICAL VAPOR DEPOSITION SYSTEM, each of which applications is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The disclosure generally relates to coatings for optical lenses and other substrates. More particularly, the disclosure relates to a physical or chemical vapor, corona method, or thermal evaporation deposition system and method which facilitate sequential application of coatings to an optical lens or other substrate by gravity-actuated transfer of the substrates between successive deposition chambers. 
     BACKGROUND OF THE INVENTION 
     Optical lenses of eyewear such as eyeglasses and sunglasses may include one or more optical coatings which impart a desired appearance or optical characteristic to the lenses. An optical coating includes one or multiple layers of material which are deposited on one or both sides of an optical lens and affects the manner in which the lens reflects and transmits light. Antireflective coatings and high-reflective coatings are examples of optical coatings which may be applied to an optical lens. 
     A common method of applying an optical coating to an optical lens includes dipping the lens in a solution which adheres to one or both surfaces of the lens upon removal of the lens from the solution and then curing the solution to form the coating. Another method of applying an optical coating to an optical lens involves applying the coating to one or both surfaces of the lens using a physical vapor deposition (PVD) process. 
     In some applications, it may be necessary or desirable to sequentially apply multiple layered coatings to one or both surfaces of an optical lens. For example, application of optical coatings to one or both surfaces of optical lenses for eyewear may include application of metallic, dielectric, dichroic, hydrophobic, oleophobic or super hydrophobic coatings to the lenses in a sequential manner. One challenge, which is inherent in the serial application of coatings to optical lenses, is the transfer of each lens among multiple deposition chambers in a manner which is both efficient and does not risk physical contact or contamination of the freshly-applied coatings on the lens. 
     Therefore, a physical vapor deposition (PVD) system which facilitates sequential application of coatings to an optical lens or other substrate by gravity-actuated transfer of the substrates between successive PVD chambers is needed. 
     SUMMARY OF THE INVENTION 
     The disclosure is generally directed to a physical vapor deposition system. An illustrative embodiment of the system includes a system housing having a housing interior, a fixture transfer assembly having a generally sloped fixture transfer rail extending through the housing interior, a plurality of processing chambers connected by the fixture transfer rail, a controller interfacing with the processing chambers and at least one fixture carrier assembly carried by the fixture transfer rail and adapted to contain one substrate. The fixture carrier assembly travels along the fixture transfer rail under influence of gravity. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will now be made, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is a left side front perspective view of an illustrative embodiment of the vapor deposition system, with the system housing in an open configuration; 
         FIG. 2  is a right side front perspective view of an illustrative embodiment of the vapor deposition system, with the system housing in an open configuration; 
         FIG. 3  is a perspective view of an illustrative embodiment of the vapor deposition system, with the system housing in a closed configuration; 
         FIG. 4  is a perspective view of a film application system of an illustrative embodiment of the vapor deposition system; 
         FIG. 5  is a block diagram which illustrates interconnection of the various subsystem components of the physical vapor deposition system; and 
         FIG. 6  is a flow diagram of an illustrative embodiment of a physical vapor deposition method. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to practice the disclosure and are not intended to limit the scope of the appended claims. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
     Referring initially to  FIGS. 1-4  of the drawings, an illustrative embodiment of the physical vapor deposition system, hereinafter system, is generally indicated by reference numeral  100 . As will be hereinafter further described, the system  100  is adapted to sequentially apply one or more coatings (not illustrated) on one or both surfaces (not illustrated) of a substrate (not illustrated) using a physical vapor deposition (PVD) process. In some applications, the substrate may be an optical lens of eyewear such as eyeglasses or sunglasses, for example and without limitation. The coating(s) which is/are applied to the substrate may be hydrophobic, oleophobic or super hydrophobic coatings, for example and without limitation, which may serve as antireflective coatings, high-reflector coatings or other optical coatings known in the art. The PVD processes which are used to apply the coatings to the substrate may be sequentially carried out in a series of multiple processing chambers  185  ( FIG. 4 ). Each substrate may be transferred from one processing chamber  185  to the next processing chamber  185  in the deposition process via gravity, as will be hereinafter further described. 
     The system  100  may include a system housing  122 . In some embodiments, the system housing  122  may include a pair of side housing panels  123 , a top housing panel  127  and a rear housing panel  128  which define a housing interior  124 . The housing interior  124  may be divided into a lower subsystem compartment  125  and an upper chamber compartment  126 . The subsystem compartment  125  may contain various subsystem components of the system  100  which will be hereinafter described. The chamber compartment  126  may contain a film application system  184  having multiple processing chambers  185 . In operation of the system  100 , which will be hereinafter described, the processing chambers  185  implement etching and physical vapor deposition functions in the processing of substrates. 
     As illustrated in  FIGS. 1-4 , the system housing  122  may include at least one front subsystem compartment door  130  provided on the system frame  101 . In some embodiments, the system housing  122  may have multiple, adjacent front subsystem compartment doors  130 . The front subsystem compartment doors  130  may be selectively opened to expose the subsystem compartment  125  at the front portion of the housing interior  124 , as illustrated in  FIGS. 1 and 2 , or selectively closed to conceal the subsystem compartment  125  at the front portion of the housing interior  124 , as illustrated in  FIG. 3 . 
     In some embodiments, the system housing  122  may further include at least one rear subsystem compartment door (not illustrated) provided on the system housing  122 . The rear subsystem compartment door may be selectively opened to expose the subsystem compartment  125  at the rear portion of the housing interior  124  or selectively closed to conceal the subsystem compartment  125  at the rear portion of the housing interior  124 . 
     The system housing  122  may include at least one front chamber compartment door  132  to selectively expose and conceal the chamber compartment  126  at the front portion of the housing interior  124 . At least one of the front chamber compartment doors  132  may have at least one window  133 . In some embodiments, the front chamber compartment door  132  may be pivotally attached to a side housing panel  123  of the system housing  122  via door hinges  137  ( FIGS. 1 and 2 ). At least one door latch (not illustrated) may be provided on each front chamber compartment door  132 . The door latch or latches may be adapted to selectively lock the front chamber compartment door or doors  132  in the closed position of  FIG. 3  or selectively unlock the front chamber compartment door or doors  132  for opening as illustrated in  FIGS. 1 and 2 . In some embodiments, at least one door extension cylinder (not illustrated) may be attached to the system housing  122 . A door extension piston (not illustrated) may be extendable from the door extension cylinder. The door extension piston may be attached to an interior surface of the front chamber compartment door  132 . Accordingly, when the front chamber compartment door  132  is closed and the door latch (not illustrated) is latched, the door extension piston is retracted into the door extension cylinder. When the front chamber compartment door  132  is open, the door extension piston extends from the door extension cylinder and maintains the front chamber compartment door  132  in the open position. 
     In some embodiments, the system housing  122  may further include a rear chamber compartment door (not illustrated) to selectively expose and conceal the chamber compartment  126  at the rear portion of the housing interior  124 . The rear chamber compartment door may have a design and attachment which are as were heretofore described with respect to the front chamber compartment door or doors  132 . 
     As further illustrated in  FIGS. 1-9 , the system  100  may include a fixture transfer assembly  146 . The fixture transfer assembly  146  may include a generally elongated fixture transfer rail  147  which extends transversely through the chamber compartment  126  of the housing interior  124  in the system housing  122 . The fixture transfer rail  147  may have a fixture loading end  148  and a fixture unloading end  149 . A lower loading ramp segment  153  and an upper loading ramp segment  153   a , and a lower unloading ramp segment  154  and an upper unloading ramp segment  154   a , of the fixture transfer rail  147  may protrude beyond the respective loading and unloading ends, respectively, of the system housing  122 . The fixture transfer rail  147  may generally slope downwardly from the fixture loading end  148  to the fixture unloading end  149 . 
     The fixture transfer rail  147  of the fixture transfer assembly  146  may be mounted in the chamber compartment  126  of the housing interior  124  according to any suitable technique which is known by those skilled in the art. In some embodiments, the fixture transfer assembly  146  may include a generally elongated chamber support member (not illustrated) which extends through the chamber compartment  126  in generally transverse relationship to the longitudinal axis of the system housing  122 . The chamber support member may be attached to any structural component of the system housing  122  using welding, fasteners and/or other suitable attachment technique. The fixture transfer rail  147  may be sloped with respect to the horizontal at a slope angle of about 91.50 degrees. 
     As illustrated in  FIGS. 1-3 , the fixture transfer assembly  146  may further include at least one fixture carrier assembly  156 . In some embodiments, the fixture transfer assembly  146  may include multiple fixture carrier assemblies  156 , as illustrated. Each fixture carrier assembly  156  may include an annular assembly frame  157  having a frame opening  158 . A fixture mount plate (not illustrated) having a fixture opening may be provided in the frame opening  158 . The fixture opening is sized and configured to receive and secure a single substrate (not illustrated) typically in the conventional manner. 
     As illustrated in  FIGS. 1 and 2  of the drawings, a film application system  184  having multiple processing chambers  185  ( FIG. 4 ) is provided in the chamber compartment  126  of the housing interior  124 . The processing chambers  185  have physical vapor deposition capabilities according to the knowledge of those skilled in the art. At least one of the processing chambers  185  may have substrate etching capabilities. As illustrated in  FIG. 5 , in some embodiments, the processing chambers  185  may include a first processing chamber  185   a , a second processing chamber  185   b  and a third processing chamber  185   c  which are sequentially ordered between the lower and upper loading ramp segments  153 ,  153   a  on one side and the lower and upper unloading ramp segments  154 ,  154   a  on the other side of the system housing  122 . Therefore, the processing chambers  185  may assume the sloped or angled orientation of the fixture transfer rail  147 . 
     Each processing chamber  185  is adapted to receive by gravity and contain a fixture carrier assembly  156  having a substrate (not illustrated) retained therein for processing of the substrate. As illustrated in  FIG. 4 , a fixture entry valve  188  may be disposed in fluid communication with each processing chamber  185  at an inlet side of the processing chamber  185 . A fixture outlet valve  189  may be disposed in fluid communication with the processing chamber  185  at an outlet side of the processing chamber  185 . The fixture entry valves  188  and the fixture outlet valves  189  may couple the first processing chamber  185   a  to the second processing chamber  185   b  and the second processing chamber  185   b  to the third processing chamber  185   c  with a vacuum-tight seal in the chamber compartment  126  of the housing interior  124 . In operation of the system  100 , which will be hereinafter further described, the fixture entry valve  188  and the fixture outlet valve  189  may facilitate sequential transfer of each of multiple fixture carrier assemblies  156  into and out of, respectively, each processing chamber  185 . 
     As further illustrated in  FIG. 4 , the film applicator system  184  may include a roughing pump  190  which is disposed in fluid communication with each processing chamber  185  through a roughing pump conduit  191 . Multiple water-cooled evaporation sources (not illustrated) may be provided in each processing chamber  185 . A water chiller (not illustrated) may be connected to the water-cooled evaporation sources through a pair of water hoses. An evaporation power supply (not illustrated) may be electrically connected to the water-cooled evaporation sources through a pair of power cables. 
     At least one liquid delivery injection arm (not illustrated) may be disposed in fluid communication with each processing chamber  185 . In some embodiments, a pair of front and rear liquid delivery injection arms may be disposed in fluid communication with each processing chamber  185 . An arm internalization mechanism (not illustrated) may engage each liquid delivery injection arm for internalization of the liquid delivery injection arms through respective front and back side liquid delivery ports (not illustrated) into the processing chamber  185  in operation of the system  100 . When in the internalized configuration, the liquid delivery injection arms may be positioned on opposite front and back sides of the fixture carrier assembly  156 . A deposition liquid delivery system (not illustrated) may be disposed in fluid communication with the liquid delivery injector arms through liquid delivery lines. 
     A turbomolecular pump (not illustrated) may be disposed in fluid communication with each processing chamber  185 . Each processing chamber  185  may include a fixture rotation mechanism (not illustrated) which facilitates rotation of the fixture carrier assembly  156  in the processing chamber  185 . The fixture rotation mechanism may include a movement sensor (not illustrated) which senses movement of the fixture carrier assembly  156  in the processing chamber  185 . A vacuum valve (not illustrated) may be disposed in fluid communication with the processing chamber  185  in communication with the turbomolecular pump. 
     It will be recognized and understood that the foregoing description of each processing chamber  185  is a general description and it will be recognized and understood that processing chambers of various design which are known by those skilled in the art may be suitable for the purpose of etching and depositing coatings on substrates using physical vapor deposition techniques in operation of the system  100 . Some processing chambers  185  which are suitable for implementation of the system  100  may depart in at least some design details from the foregoing description of the processing chamber  185  which was set forth herein above with respect to  FIG. 4 . At least one of the processing chambers  185  may have any etching chamber design with necessary hardware which is suitable for etching and cleaning of the substrates preparatory to deposition of coatings on the substrates by operation of the processing chambers  185 . Etching chamber designs are well-known by those skilled in the art; therefore, the hardware and design of the etching chamber  198  need not be set forth herein in detail. Generally, the etching chamber may include a fixture entry valve  188  and a fixture outlet valve  189  which facilitate entry and exit of individual fixture carrier assemblies  156  into and out of, respectively, the etching chamber, as was heretofore described with respect to the processing chambers  185  in  FIG. 4 . 
     Referring next to  FIG. 5  of the drawings, a block diagram of a control system  216  which is suitable for implementation of the physical vapor deposition system  100  is illustrated. The control system  216  may include a programmable logic controller (PLC)  222 . A human-machine interface (HMI)  224  may interface with the PLC  222 . The HMI  224  may include a keyboard, mouse and/or other elements which may be used to program the PLC  222  to operate the multiple functions of the system  100 . An electrical distribution panel  220  may interface with the PLC  222 . The various functional components of the system  100  may be electrically connected to the electrical distribution panel  220 . Accordingly, the PLC  222  may be adapted to operate the various subsystems of the system  200  through the electrical distribution panel  220 . 
     Some of the subsystems of the system  100  may include a roughing pump  190 , water-cooled evaporation sources  194 , a deposition liquid delivery system  204 , a fixture rotation mechanism  211 , a fixture entry valve  188 , a fixture outlet valve  189  and a turbomolecular pump  210 , each of which is disposed inside or interfaces with the processing chamber  185 . The evaporation power supply  200  may be electrically connected to the electrical distribution panel  220  and the water-cooled evaporation sources  194  in the processing chamber  185 . The water chiller  195  may be electrically connected to the electrical distribution panel  220  and disposed in fluid communication with the water-cooled evaporation sources  194 . In some embodiments, an entry position sensor  192  may be connected to the electrical distribution panel  220  and disposed at the entry position of the processing chamber  185  adjacent to the fixture entry valve  188 . The entry position sensor  192  may be adapted to sense the fixture carrier assembly  156  at the entry position of the processing chamber  185  and enable the PLC  222  to open the fixture entry valve  188  of the processing chamber  185  for entry of the fixture carrier assembly  156  into the processing chamber  185 , as will be hereinafter described. As further illustrated in  FIG. 5 , in some embodiments, a chamber cooling system  236  may interface with each processing chamber  185  and the electrical distribution panel  220  for the purpose of cooling the interior of the processing chamber  185 . 
     Some of the subsystems of the system  100  may be contained in the subsystem compartment  125  ( FIGS. 1 and 2 ) of the housing interior  124 . In some embodiments, the roughing pumps  190 , the water chiller  195  and the evaporation power supply  200  may be contained in the subsystem compartment  125  in the front portion of the housing interior  124 . The electrical distribution panel  220  and the PLC  222  may be contained in the subsystem compartment  125  in the rear portion of the housing interior  124 . The subsystems can be selectively exposed and accessed for repair, replacement and/or maintenance purposes by opening the front subsystem compartment doors  130  ( FIG. 1 ) and the rear subsystem compartment door (not illustrated). Likewise, the PVD chambers  185  can be selectively exposed and accessed for repair, replacement and/or maintenance purposes by opening the front chamber compartment door  132  and the rear chamber compartment door (not illustrated). 
     In exemplary application, the system  100  is operated to apply one or multiple coatings (not illustrated) to one or both sides of a substrate (not illustrated) in a sequential manner using a physical vapor deposition (PVD) process. In some applications, the substrate may be an optical lens which will be used in the assembly of eyewear such as eyeglasses or sunglasses, for example and without limitation. For example and without limitation, in some applications, the system  100  may be operated to plasma etch the front and backsides of an optic lens; apply a mirror coating to the front of the lens; and apply an oleophobic/hydrophobic coating to the front and backside of the lens. In other applications, the substrate may be any type of substrate to which one or more coatings is to be applied using a PVD process. 
     A substrate is secured in each of multiple fixture carrier assemblies  156  ( FIGS. 1-3 ). As will be hereinafter further described, each fixture carrier assembly  156  serves as a vehicle for transport of the substrate between and within the sequential processing chambers  185 . Accordingly, each substrate may initially be secured in the frame opening  158  of a corresponding fixture carrier assembly  156 . 
     As illustrated in  FIGS. 2 and 3 , at least one fixture carrier assembly  156  (each containing a substrate  182  held therein) is initially placed on the lower loading ramp segment  153  of the fixture transfer rail  147 . In some embodiments, multiple fixture carrier assemblies  156  may be placed in series on the lower loading ramp segment  153  of the fixture transfer rail  147 , as illustrated. Each fixture carrier assembly  156  may be inserted in place between the lower loading ramp segment  153  and the upper loading ramp segment  153   a  such that a circumferential rail groove (not illustrated) in the assembly frame  157  of the fixture carrier assembly  156  receives the lower loading ramp segment  153  and the upper loading ramp segment  153   a  of the fixture transfer rail  147 . Therefore, each fixture carrier assembly  156  is self-standing between the lower loading ramp segment  153  and the upper loading ramp segment  153   a.    
     Due to the angled or sloped configuration of the lower loading ramp segment  153  and the upper loading ramp segment  153   a , each fixture carrier assembly  156  has a tendency to roll under influence of gravity on the fixture transfer rail  147  from the fixture loading end  148  toward the fixture unloading end  149  thereof. Accordingly, the fixture carrier assembly  156  which is first in the series of multiple fixture carrier assemblies  156  on the loading ramp segment  153  rolls to a “ready” position adjacent to a fixture entry valve  188  at the inlet of the first processing chamber  185   a . A second fixture carrier assembly  156  rolls into the space which was previously occupied by the first fixture carrier assembly  156 , and the remaining fixture carrier assemblies  156  roll into the spaces previously occupied by the preceding fixture carrier assemblies  156 , respectively. 
     The system  100  is initialized and enters a standby condition as the PLC  222  ( FIG. 5 ) is turned on. The operational parameters (temperature, pressure, etc.) for the etching process which is to be carried out and for each of the deposition processes which are to be sequentially carried out in the processing chambers  185  may be programmed into the PLC  222  ( FIG. 5 ) through the HMI  224 . An entry position sensor (not illustrated) at the “ready” position adjacent to the fixture entry valve  188  of the first processing chamber  185   a  senses the location of the first fixture carrier assembly  156  at the “ready” position and transmits a signal to the PLC  222 . In response, the PLC  222  opens the fixture entry valve  188  of the first processing chamber  185   a  and the first fixture carrier assembly  156  rolls into the first processing chamber  185   a . The PLC  222  then closes the fixture entry valve  188  of the first processing chamber  185   a  and establishes the programmed pressure in the first processing chamber  185   a . The next fixture carrier assembly  156  in line on the unloading ramp segment  154  rolls on the fixture transfer rail  147  under the influence of gravity into the “ready” position next to the fixture entry valve  188  of the first processing chamber  185 . 
     After the PLC  222  establishes the etching temperature, pressure and other operational parameters which were preprogrammed into the PLC  222 , the first processing chamber  185   a , under control by the PLC  222 , may operate to etch and clean both surfaces of each substrate which is held in the first fixture carrier assembly  156 . After etching and cleaning of the substrates in the first fixture carrier assembly  156  is completed, the PLC  222  opens a fixture outlet valve  189  of the first processing chamber  185  and the first fixture carrier assembly  156  rolls from the first processing chamber  185  into the entry position of the second processing chamber  185   b . The entry position sensor  192  ( FIG. 5 ) senses that the first fixture carrier assembly  156  is at the entry position of the second processing chamber  185   b  and transmits a signal to the PLC  222  indicating the entry position of the first fixture carrier assembly  156 . In response, the PLC  222  vents the first processing chamber  185   a  to atmosphere and then opens the fixture entry valve  188  of the second processing chamber  185   b . Simultaneously, the front and back side liquid delivery ports (not illustrated) of the second processing chamber  185   b  are opened and the front and rear liquid delivery injector arms (not illustrated), under actuation by the arm internalization mechanisms (not illustrated), descend into the second processing chamber  185   b . The first fixture carrier assembly  156  rolls into place in the second processing chamber  185   b . The PLC  222  then closes the fixture entry valve  188 . The PLC  222 , responsive to input from the entry sensor (not illustrated) at the “ready” position of the first processing chamber  185   a , opens the fixture entry valve (not illustrated) of the first processing chamber  185   a  and the fixture carrier assembly  156  which was next in line behind the first fixture carrier assembly  156  rolls on the fixture transfer rail  147  into the first processing chamber  185   a.    
     The deposition liquid (not illustrated) which will form the coatings on one or both surfaces of each substrate in the first fixture carrier assembly  156  is dispensed from the deposition liquid delivery system  204  ( FIG. 5 ) through the respective liquid delivery lines (not illustrated) to the liquid delivery injector arms (not illustrated). The liquid delivery injector arms dispense the deposition liquid into the water-cooled evaporation sources  194  ( FIG. 5 ) in the second processing chamber  185   b . Once the deposition liquid is fully dispensed into the evaporation sources  194 , the liquid delivery injector arms are retracted from the second processing chamber  185   b  and the liquid delivery ports (not illustrated) are closed. Next, the fixture rotation mechanism  211  ( FIG. 5 ) may rotate the first fixture carrier assembly  156  in the second processing chamber  185   b  and the PLC  222  pulls vacuum on the second processing chamber  185   b  via the roughing pump  190  and the turbomolecular pump. Once the correct level of vacuum pressure in the second processing chamber  185   b  has been achieved, the deposition liquid in the evaporation sources  194  is evaporated into the second processing chamber  185   b , coating the substrate in the first fixture carrier assembly  156 . After it determines that a predetermined period of time has elapsed to ensure thorough coating of the substrates, the PLC  222  vents the second processing chamber  185   b  to atmosphere. The PLC  222  then opens the fixture outlet valve  189  of the second processing chamber  185   b  such that the first fixture carrier assembly  156  rolls under influence of gravity the second processing chamber  185   b  to the fixture entry position of the third processing chamber  185   c . The same PVD and transfer process is then carried out on the substrates of the first fixture carrier assembly  156  in the third processing chamber  185   d  until the desired coatings have been sequentially applied to the surfaces of each substrate. As the PVD process is carried out in the second processing chamber  185   b , the substrates held in the fixture carrier assembly  156  which was next in line behind the first fixture carrier assembly  156  may be etched in the first processing chamber  185   a . The substrates in that next-in-line fixture carrier assembly  156  may then be subjected to the PVD processes in the second processing chamber  185   b  and the third processing chamber  185   c  in the same manner as the substrates in the first fixture carrier assembly  156 . 
     After the PVD processes in the third processing chamber  185   c  are completed, the fixture carrier assemblies  156  sequentially roll from the third processing chamber  185   c  onto the unloading ramp segment  154  of the fixture transfer rail  147 . The fixture carrier assemblies  156  are removed from the unloading ramp segment  154  and the substrates are removed from the frame openings  158  in the fixture carrier assemblies  156  for further processing. Between uses of the system  100 , the PLC  222  may periodically operate the chamber cooling system  236  ( FIG. 5 ) to clean the interior of each processing chamber  185  as deemed necessary. 
     It will be appreciated by those skilled in the art that the physical vapor deposition system  100  is capable of processing substrates in multiple fixture carrier assemblies  156  at the same time by simultaneous operation of the processing chambers  185 . This expedient facilitates high-speed, low-volume and high-throughput production of thin film-coated substrates using physical vapor deposition processes. Moreover, transfer of the fixture carrier assemblies  156  between the processing chambers  185  by gravity eliminates the need for mechanical structure and related power supply which would otherwise be required for the transfer operation. The system  100  may be designed such that the chamber functions and capabilities are flexible and can be adapted for various types of physical vapor deposition applications on different types of substrates. Examples include but are not limited to ophthalmic mirror coatings, ophthalmic anti-reflective coatings, protective coatings, cosmetic coatings, compact disc manufacturing and medical device manufacturing. The construction methods and materials for the system  100  may be tailored according to the particular thin films which are to be applied to the substrates. The system  100  may be constructed in any of various sizes depending on the desired application. Various alternative designs for the subsystems, assemblies and components may be used in various embodiments of the system  100 . The system  100  may be fabricated using a variety of fabrication techniques including but not limited to welding, brazing, connectors, terminal blocks, screws, bolts, nuts and clamps. 
     It will be further appreciated by those skilled in the art that each processing chamber  185  may contain multiple water-cooled evaporation sources  194  ( FIG. 5 ) to enhance the flexibility of the physical vapor deposition system  100 . Thus, multiple types of physical vapor deposition by evaporation processes can be carried out in each processing chamber  185 . The system housing  122  may be fabricated with a small footprint to facilitate ease and space efficiency in placement of the physical vapor deposition system  100  in retail locations. 
     Various structural provisions instead of or in addition to those which were heretofore described with respect to the drawings may be made for the functioning and distribution of the vacuum subsystem, pneumatic subsystem, electrical subsystem and/or any other subsystems or components which may be deemed necessary for operation of the processing chambers  185  or any other operational component or subsystem of the system  100 . For example and without limitation, vacuum system conduits (not illustrated) may be routed throughout the housing interior  124  to provide connection between the roughing pumps  190 , turbomolecular pumps and/or other pumps and the processing chambers  185 . Pneumatic system conduits (not illustrated) may provide connection between vacuum subsystem components or pneumatic subsystem components and the processing chambers  185 . Pneumatic system ports (not illustrated) may be provided in the fixture transfer rail  147  and/or other structural components of the system  100  for functioning of the pneumatic subsystem. Other structural provisions may include whichever supports, wiring and plumbing may be necessary to interconnect all components and subsystems. 
     The film applicator system  184  ( FIG. 17 ) of the system  100  may be designed as a stand-alone unit, as part of an in-line physical vapor deposition system or as part of a larger, more complex system. The film applicator system  184  can coat one side or two sides of a substrate and a two-sided coating applied to the substrate may be performed individually or simultaneously at high speeds and high throughput. The film applicator system  184  may be operated manually, semi-automatically or fully automatically via a computer or the PLC  222  and HMI  224  ( FIG. 5 ). 
     The fixture carrier assemblies  156  may be constructed of various materials depending on the particular application. The fixture carrier assemblies  156  may be constructed for single-side application and may be fabricated in various sizes. Alternative methods of holding the substrate in the frame opening  158  of each fixture carrier assembly  156  may be used. Moreover, the design of each fixture carrier assembly  156 , as well as each processing chamber  185  as described and illustrated herein, may facilitate uniform coating of either or both surfaces of each substrate depending on the desired application. 
     Referring next to  FIG. 6  of the drawings, a flow diagram  2300  of an illustrative embodiment of a physical vapor deposition method is illustrated. In block  2302 , a sloped gradient is provided. In block  2304 , processing chambers are placed along the sloped gradient. In some applications, the processing chambers may include an etching chamber and at least one physical vapor deposition (PVD) chamber. In some embodiments, the processing chambers may include an etching chamber and multiple sequentially-ordered PVD chambers. In block  2306 , at least one fixture carrier assembly is provided. In block  2308 , a substrate is placed in the fixture carrier assembly. In block  2310 , the fixture carrier assemblies are transported into and between the processing chambers along the sloped gradient under the influence of gravity. The design of each PVD chamber and each fixture carrier assembly may facilitate uniform deposition of one or more coatings on either or both surfaces of each substrate. 
     While various illustrative embodiments of the disclosure have been described above, it will be recognized and understood that various modifications can be made in the disclosure and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the embodiments of the disclosure.