Patent Publication Number: US-2020285061-A1

Title: Heads up display systems for swimming goggles

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/960,436 filed on Apr. 23, 2018, which claims the benefit of priority of U.S. Provisional Patent Application No. 62/488,516, which was filed on Apr. 21, 2017, both of which are hereby incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to heads up display (HUD) systems, and in particular to HUD systems for use with swimming goggles. 
     BACKGROUND 
     The advent of small, low power, and reliable electronic sensors, processors and related components has led to an increase in the practicality and popularity of wearable computing devices. Various wearable computing devices for use by swimmers have been proposed, including:
     US Patent Application Publication No. 2010/0030482;   US Patent Application Publication No. 2010/0134297;   US Patent Application Publication No. 2013/0187786; and   International (PCT) Application Publication No. WO 2015/164944.   

     The inventors have determined a need for improved systems and methods for providing swimmers with real time information while swimming. 
     SUMMARY 
     One aspect provides a heads up display (HUD) system configured for use with a pair of swimming goggles comprising first and second eye cups, a nose bridge connected to an inner side of each of the first and second eye cups, and a strap mounting portion on an outer side of each of the first and second eye cups. The HUD system comprises an electronics module and an optics module. The electronics module comprises a water tight housing and a processor, memory, power supply, one or more sensors and a display within the water tight housing. The processor processes signals from the one or more sensors to determine swimming performance data and controls the display to generate an image containing the swimming performance data. The optics module is mounted on one of the first and second eye cups and is coupled to the electronics module for receiving the image from the display. The optics module extends from the electronics module and has one or more light directing features for redirecting the image toward an eye of a user to generate a redirected image. 
     Further aspects and details of example embodiments are set forth below. 
    
    
     
       DRAWINGS 
       The following figures set forth embodiments in which like reference numerals denote like parts. Embodiments are illustrated by way of example and not by way of limitation in the accompanying figures. 
         FIG. 1  shows a pair of swimming goggles with a heads up display (HUD) system removeably mounted thereon. 
         FIG. 1A  shows the swimming goggles and HUD system of  FIG. 1  with the HUD system removed from the goggles. 
         FIG. 1B  is a top view of the swimming goggles and HUD system of  FIG. 1 . 
         FIG. 1C  shows the HUD system of  FIG. 1  in isolation. 
         FIG. 2  shows a pair of swimming goggles with an integrated HUD system. 
         FIG. 2A  shows the swimming goggles and HUD system of  FIG. 2  with the electronics module of the HUD system separated from the goggles. 
         FIG. 2B  is a top view of the swimming goggles and HUD system of  FIG. 2 . 
         FIG. 3  is a schematic block diagram of an example electronic system for a HUD system according to the present disclosure. 
         FIG. 4  shows a pair of swimming goggles with an integrated HUD system with an optics module integrated into one of the eye cups. 
         FIG. 4A  shows the swimming goggles and HUD system of  FIG. 4  with the electronics module of the HUD system and the optical module cap separated from the goggles. 
         FIG. 5  shows the eye cup having the integrated optics module of the goggles of  FIG. 4  in isolation. 
         FIG. 5A  is a sectional view along line A-A of  FIG. 5 . 
         FIG. 5B  is an enlarged view of the area indicated by circle B in  FIG. 5A . 
         FIG. 5C  is an enlarged view of the area indicated by circle C in  FIG. 5A . 
         FIG. 5D  is an exploded view of the eye cup of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
     The following describes heads up display (HUD) systems for use with swimming goggles. Example embodiments described below include HUD systems adapted to be removeably mounted on a pair of swimming goggles, and HUD systems integrated into a pair of swimming goggles. The HUD systems disclosed herein are useful for providing a near-eye data feed to swimmers in real time, who otherwise would be isolated from information during activity. The data feed provides critical data about the swimming activity such as for example time, splits, lap count, distance and breathing rate but can also include text notifications to the swimmer for technique tips (e.g. body or head position), encouraging messages to boost motivation, or messages from the coach, as described further below. 
     For simplicity and clarity of illustration, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. Numerous details are set forth to provide an understanding of the examples described herein. The examples may be practiced without these details. In other instances, well-known methods, procedures, and components are not described in detail to avoid obscuring the examples described. The description is not to be considered as limited to the scope of the examples described herein. 
       FIG. 1  shows a pair of swimming goggles G with a heads up display (HUD) system  100  removeably mounted thereon. The goggles G have a pair of eye cups E 1  and E 2  with a nose bridge B connected between an inner side of each of the eye cups E 1  and E 2 . Each of the eye cups E 1  and E 2  has a strap mounting portion S on its outer side. 
     The HUD system  100  comprises an optics module  110  and an electronics module  120 , and a resilient loop member  102  configured to secure the HUD system  100  to one of the eye cups E 1  or E 2 . As discussed further below, the electronics module  120  generates an image containing swimming performance data which is directed toward a user&#39;s eye by the optics module  110 . 
     The optics module  110  comprises a transparent member  111  extending from the electronics module  120 . The transparent member  111  has a viewing surface  119  configured for placement against the front side of one of the eye cups E 1  or E 2 . The optics module  110  is held in place against the goggle eye cup E 1 /E 2  by a resilient loop member  102  stretched between the bridge B and mounting portion S and over protrusions  112  on the transparent member  111 . 
     In the illustrated example embodiment, the protrusions  112  are symmetrically positioned on the top and bottom of the transparent member. Each of the top and bottom protrusions  112  comprises a flange  113  extending outwardly from the edge of the transparent member  111  adjacent to the viewing surface  119 , and a hook  114  at an end of the flange  113  closest to the electronics module  120 . This configuration allows the viewing surface  119  to be securely held against the front surface of the eye cup E 1 /E 2  by a single loop member  102  looped around the bridge B and mounting portion S, as shown in  FIG. 1A , by stretching the loop member  102  for placement over the flanges  113  and hooks  114  on the top and bottom of the transparent member  111 . To account for different sized goggles, the unstretched size of the loop member  102  may be selected based on the distance between the bridge B and mounting portion S to ensure that the transparent member  111  is held securely. 
     In other embodiments, the protrusions  112  may take different forms. For example, in some embodiments the flanges  113  could be replaced with another pair of hooks or the like near the end of the optics module. In some embodiments one loop may be provided for attaching to the strap around hooks near the electronics module, and another loop for attaching to the bridge around a hook on the end of the optics module. 
     The electronics module  120  comprises an electronic system having a processor and a plurality or sensors for generating signals indicative of swimming performance data, and a display device for sending light signals to the optics module  110 , as described further below. The electronics module  120  comprises an optical module interface  122  for coupling light from the display device within the electronics module  120  into the optics module  110 . The optics module  110  comprises light directing elements within the transparent member  111  for directing light towards the viewing surface  119 . For example, in some embodiments, the optics module comprises a holographic waveguide (e.g. a transparent substrate such as a glass plate or the like, with a first hologram for receiving an image from the display and redirecting light to a second hologram which redirects light towards the viewing surface  119 ), and the light directing elements may comprise holographic beam splitters. The holographic waveguide may be located within a cavity defined in the transparent member, with spacings around the waveguide to leave gaps for maintaining total internal reflection, as described below. 
     As best seen in  FIGS. 1B and 1C , the electronics module  120  also comprises a port  124 , such as for example a micro-USB port. In some embodiments, the port  124  comprises an IP68 10 m waterproof Micro-USB connector. This Micro-USB connector is sealed through the body of the connector and has a rubber seal around the outside that seals with a mating port in the housing of the electronics module  120 . As an alternative to a waterproof micro-USB connector, the port  124  may, for example, comprise pogo-pin contacts embedded in the wall of the housing of the electronics module  120 , and a custom USB cable may be provided for connecting to the pogo-pin contacts. The port  124  allows the HUD system  100  to be connected to a power source for charging the battery, and/or connected to another electronic device for wired data transfer. In other embodiments, the HUD system  100  comprises a wireless charging receiver such that the battery may be charged wirelessly. The electronics module  120  may also comprise one or more user interface elements, which in the illustrated example include a power button  126 , a wireless activation button  128 , and a touch sensitive region  129 . The electronics module  120  may also comprise an ambient light sensor  127  for detecting ambient lighting conditions. 
       FIGS. 2, 2A and 2B  show a pair of swimming goggles G′ with an integrated HUD system  200  comprising an electronics module  220  and an optics module  230 . In HUD system  200 , the optics module  230  is formed within one of the goggles eye cups, and a mounting portion  212  extending laterally outwardly from the eye cup is configured to engage an optical module interface  222  of the electronics module  220 . In some embodiments, the electronics module  220  is removable from the goggles G′, such that the goggles G′ may be provided separately from the electronics module  220 , and users can purchase goggles and electronics modules separately. 
     The electronics module  220  comprises an electronic system having a processor and a plurality of sensors for generating signals indicative of swimming performance data, and a display device for sending light signals to the optics module  230 , as described further below. The optics module  230  comprises light directing elements within the eye cup for directing light generated in the electronics module  220  towards the user&#39;s eye. Details of an example optics module consisting essentially of a collimating optic, a waveguide, a corrective optic and a cap are described below with reference to  FIGS. 4 to 5D . The optics module  230  may take other forms in other embodiments. 
     As best seen in  FIG. 2B , the electronics module  220  also comprises a port  224 , such as for example a micro-USB port. In some embodiments, the port  224  comprises an IP68 10 m waterproof Micro-USB connector. This Micro-USB connector is sealed through the body of the connector and has a rubber seal around the outside that seals with a mating port in the housing of the electronics module  220 . As an alternative to a waterproof micro-USB connector, the port  224  may, for example, comprise pogo-pin contacts embedded in the wall of the housing of the electronics module  220 , and a custom USB cable may be provided for connecting to the pogo-pin contacts. The port  224  allows the HUD system  200  to be connected to a power source for charging the battery, and/or connected to another electronic device for wired data transfer. In other embodiments, the HUD system  200  comprises a wireless charging receiver such that the battery may be charged wirelessly. The electronics module  220  may also comprise one or more user interface elements, which in the illustrated example include a power button  226 , a wireless activation button  228 , and a touch sensitive region  229 . The electronics module  220  may also comprise status indicators  225  (e.g. LEDs) The electronics module  220  may also comprise an ambient light sensor  227  for detecting ambient lighting conditions. 
       FIG. 3  schematically illustrates elements of an electronic system  300  according to some embodiments of the present disclosure. The electronic system  300  of  FIG. 3  may, for example, be incorporated into the electronics module  120 / 220  of the HUD system  100 / 200  of  FIG. 1  or  FIG. 2 . Since the electronic system  300  is configured for use in the water, the elements of the system  300  are contained within a watertight housing  302 . The connections to the system  300  from outside the housing  302 , for example the port  124 / 224 , are waterproof. 
     The electronic system  300  comprises a low power processor  310 , a memory  312 , a plurality of sensors  314 , a display  316 , a wireless transceiver  318 , a power management integrated circuit (PMIC)  320 , a battery  322 , a port interface  324 , and one or more switches or other user interface elements  326 . The sensors  314  comprise one or more accelerometers and gyroscopes (e.g., a 6-axis accelerometer and gyroscope) for measuring acceleration and rate of turn along and about a plurality of axes. The sensors  314  provide acceleration and rate of turn signals to the processor  310 , which processes these signals by execution of computer readable instructions stored in memory  312  to generate swimming performance data. In some embodiments, the memory  312  is able to store 8 hours or more of swimming performance data. In some embodiments, the sensors  314  may include additional sensors, such as for example, an ambient light sensor, a heart rate (HR) sensor, a global positioning system (GPS) sensor, a pressure sensor, a magnetometer, and/or other sensors (e.g. body worn sensors for advanced motion or biometrics detection and analysis). In some embodiments, the electronic system  300  may also receive signals from additional sensors separate from the HUD system  100 / 200  through the wireless transceiver  318 . The processor  310  drives the display  316  to generate light based on the swimming performance data, and light from the display  316  is projected into the optics module  110 / 210  of the HUD system  100 / 200  for generating an image viewable by the user containing swimming performance information. The display  316  may comprise a monochrome display, an RGB display, or other type of display. The display  316  may, for example, comprise a low resolution OLED display. 
     In some embodiments, the processor  310 , memory  312 , sensors  314 , wireless transceiver  318  and PMIC  320  may all be incorporated into a single, low-power module such as, for example the Intel® Curie™ module, or the ST Microelectronics STM32L4. The display  316  may, for example comprise an OLED display with a resolution of 64×32 or 72×40. In some embodiments, the electronic system  300  may interface with a camera (either integrated into the HUD system or provided as a separate accessory) to enable video recording and photos. 
     The electronic system  300  includes firmware for driving the sensors  314  and software for calculating, storing, exporting/importing and displaying the resulting swimming performance data and related information. In some embodiments, the electronic system  300  is controllable by means of a multi-purpose button of the user interface elements  326  for toggling (one press) and selecting (hold) for setting up, configuring and controlling the electronic system  300 . The electronic system  300  may also be paired to or otherwise communicatively coupled to another electronic device (e.g. a smartphone, tablet, computer, etc.) for setting up, configuring and controlling the electronic system  300 , for importing and exporting performance data and related information, and/or for interfacing with online platforms (e.g. www.swim.com). For example a user may configure the electronic system  300  for use in pools having different lengths (e.g., 25 meters, 50 meters, custom), to use different measurement units (e.g. meters, yards), to set desired performance metrics or targets and measure actual performance against such targets (such as for example pace, stroke rate, SWOLF (sum of time and stroke count to complete a given distance), calories burned, total swimming time, total swimming distance, total number of laps, workout duration, turn power, turn time, underwater time, number of underwater kicks, etc.), to select the type of performance information displayed to the user, to select the frequency of pop-up messages or other communications displayed to the user. In some embodiments, the electronic system  300  may display pop-up messages to the user based on comparisons of the user&#39;s performance to various benchmarks or targets, such as a target pace, target stroke rate, target split time, recent performances, average performance, personal best, etc., or may display messages from an external source (e.g. from an electronic device used by a coach or trainer). 
     The computation required for delivering many of the described features relies on detection of certain events as determined by the onboard motion sensors (e.g., 6-axis accelerometer and gyroscope). Certain types of events that may be detected by HUD systems according to the present disclosure are listed in the table below. 
     
       
         
           
               
            
               
                   
               
               
                 Event Detection 
               
            
           
           
               
               
            
               
                 Event 
                 Description 
               
               
                   
               
               
                 Auto Start Workout 
                 Detects when user is pushing off wall 
               
               
                 Auto Finish 
                 Used to start/stop activity when swimmer is at rest between 
               
               
                   
                 swims. Detection occurs either when head is out of water in 
               
               
                   
                 vertical position and/or when wall finish is detected without 
               
               
                   
                 immediately turning in opposite direction. 
               
               
                 Auto Rest Timer 
                 Determines time between touching wall (without flip turn) and 
               
               
                   
                 pushing off again 
               
               
                 Detect Swim 
                 Auto detect activity defined as movement between rests. 
               
               
                 Detect Stroke Type 
                 Auto detect type of swim stroke based on accelerometer and/or 
               
               
                   
                 gyroscope signals (e.g. free, fly, breast, back, kick, IM, drill 
               
               
                   
                 (mixed)). 
               
               
                 Timer 
                 Auto start timer when pushing off wall for swim, stop timer after 
               
               
                   
                 each swim. 
               
               
                 Auto split 
                 Split time and distance per swim at each turn for all strokes 
               
               
                 Distance 
                 Total distance; current swim distance (per lap unit); distance since 
               
               
                   
                 last turn; distance per stroke 
               
               
                 Pace 
                 Time per 50 or 100. Pops up after each turn in increments of 50 
               
               
                   
                 for all strokes 
               
               
                 Speed 
                 In a pool, determined based on the time and the number of 
               
               
                   
                 completed laps plus distance since last turn; in open water, 
               
               
                   
                 determined based on the time and the average distance per stroke 
               
               
                   
                 combined with various sensor inputs (e.g. from accelerometer, 
               
               
                   
                 gyroscope and magnetometer) 
               
               
                 Auto split per 
                 Accelerometer detects turn automatically and splits clock per 
               
               
                 swimming type at turn  
                 distance/laps. In some embodiments, the gyroscope is used in 
               
               
                 (fly, back, crawl,  
                 combination to detect the start of a turn and in response control 
               
               
                 breast, kick)  
                 the accelerometer to have a faster sampling rate to detect change 
               
               
                   
                 in direction of motion and push-off from wall. Gyroscope could 
               
               
                   
                 also be used alone by calculating the 180 degree angular 
               
               
                   
                 acceleration from horizontal to horizontal either in z-axis (hand 
               
               
                   
                 finish) or x-axis (vertical turn). The type of turn varies based on the 
               
               
                   
                 type of stroke. Back and crawl will be almost identical and so will 
               
               
                   
                 breast and fly. Kicking finish is unique in that a kickboard is used 
               
               
                   
                 and usually only one arm touches the wall before turning. 
               
               
                 Auto lap count 
                 Use Auto Split and Auto Finish algorithms to count laps 
               
               
                 Auto On 
                 Turns device on when in water. Could be activated when push off 
               
               
                   
                 from wall is detected or when head is facing down in horizontal 
               
               
                   
                 position for x seconds. 
               
               
                 Auto Off 
                 Device turns off when no swims have been started for a given 
               
               
                   
                 timeframe (e.g. 2 min, configurable by user) and head is not in 
               
               
                   
                 horizontal position. 
               
               
                 Stroke count 
                 Counts total strokes and # stroke per minute (accelerometer) 
               
               
                 Breathing 
                 Count breaths taken per lap, per swim, per minute, etc. 
               
               
                 count/breathing rate 
                   
               
               
                 Smart Coach engine 
                 Detects technique during swim and sends feedback to the user 
               
               
                   
                 with simple tips about things like stroke mechanics, body position, 
               
               
                   
                 head position, stroke frequency, breathing rate, speed and fatigue. 
               
               
                   
                 Use sensors to pick up approximate body and head position 
               
               
                   
                 compared to ideal, and changes in body and head position. Also 
               
               
                   
                 detects when head is moved to the side for breathing, when hands 
               
               
                   
                 enters the water and exits and changes in drag by inferring 
               
               
                   
                 incorrect technique to changes in speed. Body worn sensors can 
               
               
                   
                 be worn to improve accuracy and provide extra data points for this 
               
               
                   
                 analysis. 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the electronics system  300  is configured to determine a current pace based on acceleration signals from the one or more sensors, determine an expected interval finish time based on the current pace, and display the expected interval finish time to the user in real time. In some embodiments, the electronics system  300  is configured to determine a distance travelled and display the distance travelled in the image in real time. In some embodiments, the electronics system  300  is configured to determine a swimming speed and display the swimming speed in the image in real time. 
     In some embodiments, the electronics system  300  is configured to determine a stroke type based on acceleration signals from the one or more sensors, compare a detected stroke profile to an ideal stroke profile for the determined stroke type, and display real time stroke technique feedback to the user in real time. The electronic system  300  may also send feedback regarding other performance metrics. For example, the electronic system  300  may detect a user&#39;s performance and technique during swimming and send feedback to the user with tips about things like stroke mechanics, body position, head position, stroke frequency, breathing behavior, speed, fatigue, kicking pattern, actual location in pool (e.g. right before/after turn) etc. In some embodiments, the electronic system  300  may store a variety of feedback messages and automatically display messages to the swimmer in response to certain triggering events. For example, when the system  300  detects that a swimmer&#39;s head is coming up too high, a message such as “keep your head down” could be displayed. 
     In some embodiments, the electronic system  300  is configured to determine a turn score based on a swimmer&#39;s resulting speed when coming off of a turn. This speed is a function of the power with which the swimmer pushes off the wall, and how streamlined the swimmer is after the turn. In some embodiments, the electronic system  300  is configured to determine an underwater score based on what the swimmer does after a turn. Good swimmers use dolphin kicks to propel themselves underwater avoiding waves from other swimmers in adjacent lanes and leveraging momentum from turn before resurfacing. The electronic system  300  may determine the underwater score based on how streamlined the swimmer is and effectiveness of dolphin kicks. The maximum allowed distance underwater is 15 meters so the electronic system  300  may be configured to display a warning to the swimmer prior to the swimmer travelling 15 meters underwater (e.g., at 10, 11, 12, 13, and/or 14 meters). 
     In some embodiments, the electronic system  300  provides a user in an open water swim with waypoint heading and position indicators (e.g., by displaying waypoint markers and/or arrows in the image) based on GPS signals. For example, in an example embodiment providing open water waypoint navigation, a swimmer looks at the first buoy on the course and provides user input to the HUD system (e.g. the user double taps the goggles or presses a button on the HUD system) to set course. The electronic system  300  controls the display  316  to show swimmer if he/she is veering off track and direct him/her back on straight line. Some embodiments may provide for automatic navigation, where the swimmer simply swims straight for e.g. 10 meters and the HUD system determines the current direction as a desired heading and provides visual feedback to keep the swimmer on track. For the first leg the swimmer already has the right course as he/she just looked straight at the first Buoy before jumping in. For subsequent legs of the open water swim, the swimmer just has to look up once to determine the right direction to swim in, then the HUD system provides visual feedback helping him/her stay on track. 
     In some embodiments, the electronic system  300  receives heart rate (HR) signals and compares the HR signals to a current pace, stroke rate or other performance metric to provide the user with feedback on their current effort level. 
     In addition to the features and event detection provided by on-board processing capabilities of the HUD system, some embodiments of the present disclosure also provide additional functionality through processing capabilities remote from the HUD system, such as on a server system or the like. For example, in some embodiments a server system is configured for wireless communication with one or more HUD systems. The server system may be configured to collect swimming performance data from a “Smart Coach engine” feature of the HUD system for each user in a community (e.g., a swim team, swim club or the like) and perform regression analysis to determine correlation between speed, effort and technique. This analysis can then be used by the server system to provide tips during swimming for everyone tailored to individual skill level by sending data to their respective HUD systems. The server system may collect data from swimmers on the platform correlating all the metrics collected from the Smart Coach engine and using it to provide optimized recommendations for technique correction to reduce drag and increase stroke and kick effectiveness to teach swimmers of all levels to become better and faster through tips displayed in the image in real time that fit their skillset at the time. 
       FIGS. 4 and 4A  show a pair of goggles  400  with eye cups  401  and  402  having a HUD system that includes an electronics module  420  and an example optical system  430  integrated into the eye cup  402  according to one embodiment of the present disclosure. The other eye cup  401  may be substantially similar to a standard goggle eye cup. The electronics module  420  comprises an electronic system (e.g. electronic system  300  of  FIG. 3 ) having a processor and a plurality of sensors for generating signals indicative of swimming performance data, and a display device for sending light signals to the optics module  430 . The electronics module  420  may be substantially similar to electronics module  220  described above with reference to  FIGS. 2, 2A and 2B . As described further below, the optics module  430  comprises a cap  431 , a corrective optic  433 , a waveguide  434  and a collimating optic  436 . 
     Eye cup  402  has a mounting portion  412  thereon extending laterally outwardly therefrom to engage an interface portion  422  of the electronics module  420  and accommodate portions of the optics module  430 . In the illustrated example, the mounting portion  412  has an elongated protrusion  414  and angled protrusions  416  on the top and bottom surfaces thereof, and the interface portion  422  of the electronics module  420  has correspondingly-shaped recesses to receive the protrusions  414 / 416 , such that the electronics module  420  can be slid onto the mounting portion  412  and will held in place once the protrusions  414 / 416  are received in the recesses in the interface portion  422 . In some embodiments, the interface portion  422  of the electronics module forms a watertight seal around the mounting portion  412  of the eye cup  402 . 
       FIGS. 5, 5A, 5B, 5C and 5D  show details of the eye cup  402  and optics module  430  of the example embodiment of  FIG. 4 . As best seen in  FIGS. 5A and 5D , the eye cup  402  has an inner wall  404 , with a flange  406  extending forwardly from around a periphery thereof. A lip  408  is provided extending forwardly from around the inner edge of the flange  406  and a forward facing portion of the mounting portion  412 . The cap  431  has a groove (not separately enumerated) on the rear face thereof for engaging with the lip  408 . The corrective optic  433  and waveguide  434  are held captive between the cap  431  and the inner wall  404 . A beam splitter surface (not separately enumerated) is defined by the interface of the corrective optic  433  and waveguide  434 . The waveguide  434  has a pair of flanges extending outwardly and rearwardly therefrom sized to fit around the collimating optic  436  and having apertures  435  for receiving protrusions  437  on the collimating optic  436  to maintain a desired spacing between the waveguide  434  and the collimating optic  436 . The collimating optic  436  also has protrusions  438  thereon for holding the collimating optic  436  in place within the mounting portion  412  of the eye cup  402 . In some embodiments, a watertight seal is formed between the collimating optic  436  and the mounting portion  412  of the eye cup  402 . 
     In some embodiments, the front and back surfaces of the corrective optic  433  are parallel to each other, and the front and back surfaces of the waveguide  434  are also parallel to each other. In the illustrated example, the front surface of the corrective optic  433  and the front surface of the waveguide  434  are co-planar and separated from the cap  431  by a gap  432 , as shown in  FIG. 5B , and the rear surface of the corrective optic  433  and the rear surface of the waveguide  434  are co-planar and separated from the inner wall  404  by another gap  439 . In some embodiments, each of the gaps  432  and  439  has a size of about 0.1 mm. The gaps  432  and  439  may be maintained by spacer material around a periphery of the waveguide  434 , or by any other suitable structural features. The gap  432  and  439  allow for total internal reflection of light from the display  316  within the waveguide  434 , as discussed below. In some embodiments, the gaps  432  and  439  are only present at the front and back surfaces of the waveguide  434  and not at the front and back surfaces of the corrective optic  433 . However, providing gaps  432  and  439  at the front and back surfaces of both the waveguide  434  and corrective optic  433  advantageously minimizes optical distortions in some embodiments. In some embodiments, the gaps  432  and  439  are filled with air. In some embodiments, the gaps  432  and  439  are filled with argon or another suitable gas. In some embodiments, the eye cup  402 , cap  431 , corrective optic  433  and waveguide  434  are all formed from optically transparent polycarbonate, and the collimating optic is formed from poly(methyl methacrylate) (PMMA). In some embodiments, the optical module  430  is affixed to the eye cup  402  by means of ultrasonic welding, without the use of glues or adhesives. For example, in some embodiments, an ultrasonic weld may be formed between the lip  408  of the flange  406  of eye cup  402  and the cap  431 . 
     When the electronics module  420  is in place, the display  316  is about 4 mm from an entry freeform surface of the collimating optic  436 . Light from the display  316  is collimated by the collimating optic  436  and exits form an exit freeform surface thereof and enters through an entry freeform surface of the waveguide  434 . The light is then totally internally reflected off the front surface of the waveguide  434 , the rear surface of the waveguide  434 , and then partially reflected by the beam splitter surface at the interface of the waveguide  434  and the corrective optic  433  to be directed to a pupil aperture P. In some embodiments, an image from the display  314  redirected through the optics module  430  to the pupil aperture P subtends a 20 degree horizontal angle at the pupil aperture P. In some embodiments, the beam splitter surface at the interface of the waveguide  434  and the corrective optic  433  may be a freeform surface configured to magnify an image from the display  314  after the image has passed through the collimating optic  436 . 
     To reduce optical distortion, in some embodiments the collimating optic  436  is tilted with respect to the optical axis of the optical module  430 . In some embodiments, the two freeform surfaces of the collimating optic  436  can also be independently tilted in order to reduce aberrations such as field curvature, distortion, and axial and lateral color aberrations, some of which are introduced by the off-axis configuration of the beam splitter surface at the interface of the waveguide  434  and the corrective optic  433 . By utilizing freeform surfaces, as well as tilting the collimating optic  436 , the total number of lenses required to form an image can be reduced, thus reducing the cost, complexity and weight of the optics module  430  and HUD system  400 . 
     In some embodiments, the optics module  430  comprises a holographic waveguide held in place between the cap  431  and the inner wall  404  to maintain a gap between the waveguide and the cap  431 . One or more lenses (e.g. a freeform optic lens similar to the collimating optic  436 ) may be provided between the display  316  and the holographic waveguide. 
     The present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. 
     As will be apparent to those skilled in the art in light of the foregoing disclosure, many alterations and modifications are possible to the methods and systems described herein. While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. For example: 
     the optical module  430  of  FIGS. 4-5D  could be integrated into the embodiments of  FIG. 1  or  FIG. 2 ; 
     the optical module  430  of  FIGS. 4-5D  could have additional collimating optics or other optical elements; 
     the optical elements may be tilted or decentered with respect to each other, or be of different materials; 
     the optical surfaces of the optical module  430  may be freeform, aspheric, radially-symmetric, or any other type of optical surface. 
     It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as may reasonably be inferred by one skilled in the art. The scope of the claims should not be limited by the embodiments set forth in the examples, but should be given the broadest interpretation consistent with the foregoing disclosure. 
     The foregoing discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed. 
     The embodiments of the devices, systems and methods described herein may be implemented in a combination of both hardware and software. These embodiments may be implemented on programmable computers, each computer including at least one processor, a data storage system (including volatile memory or non-volatile memory or other data storage elements or a combination thereof), and at least one communication interface. 
     Program code is applied to input data to perform the functions described herein and to generate output information. The output information is applied to one or more output devices. In some embodiments, the communication interface may be a network communication interface. In embodiments in which elements may be combined, the communication interface may be a software communication interface, such as those for inter-process communication. In still other embodiments, there may be a combination of communication interfaces implemented as hardware, software, and combination thereof. 
     Throughout the foregoing discussion, numerous references will be made regarding servers, services, interfaces, portals, platforms, or other systems formed from computing devices. It should be appreciated that the use of such terms is deemed to represent one or more computing devices having at least one processor configured to execute software instructions stored on a computer readable tangible, non-transitory medium. For example, a server can include one or more computers operating as a web server, database server, or other type of computer server in a manner to fulfill described roles, responsibilities, or functions. 
     The technical solution of certain embodiments may include a software product. The software product may be stored in a non-volatile or non-transitory storage medium, which can be a compact disk read-only memory (CD-ROM), a USB flash disk, or a removable hard disk. The software product includes a number of instructions that enable a computer device (personal computer, server, or network device) to execute the methods provided by the embodiments. 
     The embodiments described herein are implemented by physical computer hardware, including computing devices, servers, receivers, transmitters, processors, memory, displays, and networks. The embodiments described herein provide useful physical machines and particularly configured computer hardware arrangements. 
     Although the embodiments have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As can be understood, the examples described above and illustrated are intended to be exemplary only.