74 and associated removable lenses 76), may be used in storing lens information, user information, and/or other information electrically. When the removable lens system is coupled to the non-removable lens system (e.g., one or both lens modules 70 such as storage 84), electrically stored information reader 82 may retrieve the data stored in storage 84. Information reader 82 may be, for example, an electrically programmed read-only memory reader, a memory reader that reads laser-programmed storage or other programmable memory, circuitry that electrically measures storage 84 (e.g., to detect a pattern of conductive traces and/or resistive elements that are being used to store data), and/or other reader circuitry.

Information such as lens information, user information, and other information may also be stored using non-electrical storage. This storage may include, for example, bar codes, text, patterns of dots, and/or other information that can be detected optically. Optical data reading operations may be performed using infrared and/or visible cameras or other equipment (e.g., bar code scanning equipment) that reads optically encoded information. As an example, optical data reading equipment that reads data on the removable lens by imaging the removable lens such as infrared digital image sensors in gaze tracking sensors 86 and/or visible-light digital image sensors may be used in reading bar codes, text, and/or other optically encoded information.

Gaze trackers 86 (sometimes referred to as gaze monitoring systems, gaze tracking systems, eye monitoring systems, etc.) may monitor the eyes of the user in eye boxes 60 during operation of device 10. Gaze trackers 86 may include light sources and light-detecting components such as image sensors. Each gaze tracker 86 may, as an example, include a light source such as a light-emitting diode light source or laser light source that produces an array of light beams (e.g., infrared light beams that do not interfere with the vision of the user). Blanket (flood) illumination at infrared and/or visible wavelengths may also be provided. Each gaze tracker 86 may also include a respective infrared image sensor (and/or visible-light image sensor) that faces a user's eye in a respective eye box 60 and capture images of the user's eye through lenses 72 and lenses 76 while the user's eye is being illuminated with the light beams from the light source of that gaze tracker. During normal operation, control circuitry 20 may use gaze trackers 86 to track a user's gaze (e.g., so that images being displayed on displays 14 can be adjusted based on the direction of the user's gaze, etc.). When it is desired to read information in the removable lens system that has been optically stored (e.g., by encoding the information in the form of a bar code, text, etc.), one or more image sensors such as one or more infrared image sensors in one or more gaze trackers 86 may optically read the information from the supplemental lens system (e.g., from one or more lens modules 74).

FIG. 3 is a front view of an illustrative removable lens module showing arrangements that may be used to store information in the lens module. As shown in FIG. 3, lens module 74 may include lens support structures 74H. Support structures 74H may be formed from polymer, metal, and/or other materials and may surround or otherwise support lens 76 to form lens module 74. Coupling structures 80 may be supported by support structures 74H, so that coupling structures 80 hold lens module 74 to lens module 70 and support structures 26 when coupling structures 80 are coupled to mating coupling structures 78 in lens module 70.

Lens information, user information, and other information can be stored in removable lens module 74 using one or more approaches. With one illustrative arrangement, electrical storage 84 is included in lens module 74. Data may be stored in electrical storage 84. When removable lens module 74 is coupled to non-removable lens module 70, reader 82 may couple to electrical storage 84 and may retrieve the stored data from electrical storage 84.

With another illustrative arrangement, a bar code such as bar code 92 may be included in lens module 74. Bar code 92 may, as an example, be an infrared bar code that is formed from an ink that is visibly transparent while being opaque to infrared light (e.g., infrared light at the wavelength emitted by an infrared light source in gaze tracker 86) or other bar code structure that is transparent to visible light and opaque at infrared wavelengths. With this type of arrangement, bar code 92 will be transparent to the user and will not interfere with the user's viewing of content on display 14, even though bar code 92 is formed on lens 76. At the same time, gaze tracker 86 is pointed towards lens 76 so that gaze tracker 86 may capture an image of bar code 92 at infrared wavelengths.

Bar codes, text information, or other visible-light (and/or infrared light) markings may be formed from laser markings, patterned ink, patterned metal coatings, and/or other markings formed in regions such as region 90. Visible-light-encoded information of this type (e.g., information stored optically) may be read by a visible light image sensor in lens module 70 or an image sensor elsewhere in device 10 (e.g., a visible light image sensor in sensors 16). In some situations, visible-light-encoded information such as text, icons, or other optically readable patterns may contain information that is recognizable to a user (e.g., text that a user can read such as the user's name or user name, an icon that a user can recognize, etc.). User recognizable information may be used to label lens modules 74 so that lens modules that belong to different users are not mixed up. An image sensor in device 10 (e.g., an image sensor in gaze tracker 87 and/or other image sensors) may optically read text, icons, or other patterned structures on the removable lens system that are also recognizable to the user and/or the image sensor may read patterns such as bar codes and other patterns that do not contain user-recognizable text or icons.

In some situations, it may be desirable to encrypt the information that is being stored in removable lens module 74. Stored information may be encrypted using a cryptographic key. Control circuitry 12 can decrypt the encrypted information using a corresponding cryptographic key suitable for decryption (which may be the same as the encrypting key or may be related to the encrypting key). Control circuitry 12 can obtain the key from the user (e.g., using input-output devices 22). If desired, control circuitry 12 can obtain the key from a remote server (e.g., an online service). A user password, username, or other information may, if desired, be gathered from the user and/or storage in device 10 and may be used by control circuitry 12 in obtaining the key from the online service. In some arrangements, keys may be stored in control circuitry 12 for use in decrypting encrypted information stored in lens module 74 (e.g., when device 10 is only used by the members of a single household). These illustrative arrangements and/or other arrangements for encrypting and decrypting the information stored in removable lens module 74 may be used to enhance privacy for stored user information.

Illustrative steps involved in using system 8 are shown in FIG. 4.

During the operations of block 100, a user who desires to use device 10 but who has specific visual defects (astigmatism, etc.) may attach a removable lens system that is associated with that user to device 10. During attachment of the removable lens system, removable lens support structures such as lens modules 74 may be aligned with non-removable lens support structures such as lens modules 70, so that lenses 76 are aligned with corresponding lenses 72. Coupling structures 78 and 80 may be used to hold lens modules 74 and 70 together. The presence of lenses 76 in alignment with lenses 72 allows the optical properties of lenses 76 to modify the optical properties of lenses 72 (e.g., to increase or decrease lens power, to add lens asymmetry to compensate for user astigmatism, etc.). In this way, the optical system of device 10 may be tailored to the user's vision.

During the operations of block 102, control circuitry 12 of head-mounted device 10 may read information that has been stored in the removable lens system (e.g., using gaze trackers 86, a visible-light image sensor, a memory reader such as reader 82, etc.). The information that is read may be stored using a bar code, text, other optically readable patterns (e.g., patterned ink, patterned metal, or other patterned structures), and/or using electrical data storage arrangements (see, e.g., bar code 92, visible information 90, and electrically stored information in storage 84 of FIG. 3).

In general, any suitable data may be stored in the removable lens system. This information may include, for example, information regarding the user that is associated with the removable lens system such as the user's eyeglass prescription (e.g., the spherical component of the user's prescription to be handled by spherical lens power, the astigmatic component of the user's prescription to be handled by an aspherical lens power, and/or the interpupillary distance of the user's prescription), the date of the prescription, the expiration date of the prescription, the user's username and other user credentials, manufacturing information such as the date of manufacture of the removable lens system, the name of the manufacturer, a serial number, a lot number, and a model name or other model type information, lens materials for lenses 76, lens powers (e.g., spherical lens power and/or aspherical lens power) and/or other optical characteristics of lenses 76 such as known aberrations that can be later corrected using compensating image warping operations performed by control circuitry 12 during video playback, and/or other information.

After reading this information from the removable lens system during the operations of block 102, control circuitry 12 may, if desired, make adjustments to the components in device 10. These adjustments may be made based on real-time measurements from gaze trackers 86 and/or based on the stored data obtained from the removable lens system. For example, control circuitry 12 may use positioners 58 to adjust lens-to-lens spacing based on real-time measurements of the user's interpupillary distance determined from the positions of the user's pupils measured with gaze trackers 86 and/or based on stored interpupillary distance information for the user that is obtained from removable lens modules 74. Control circuitry 12 may also adjust the positions of the lenses in device 10 along the Z axis of FIG. 2 to place lenses 72 and associated supplemental lenses 76 in a satisfactory location to allow the user to view content on displays 14. These focusing adjustments with lenses 72 and 76 may be made based on the user's prescription, the powers of lenses 76, and other information obtained using the stored information in lenses 76. In arrangements in which lenses 72 have adjustable power (e.g., when lenses 72 are tunable lenses), control circuitry 12 can adjust lenses 72 to implement the spherical component of the user's prescription. The asymmetric component of a user's prescription may be handled using the asymmetric portion of supplemental lenses 76 (as an example).

After making adjustments to device 10 based on information from the supplemental lens system formed from lenses 76, a user may place device 10 on the user's head.

During the operations of block 104, control circuitry 12 may make further adjustments to the components in device 10. For example, control circuitry 12 may use positioners 58 to adjust the lens-to-lens separation of left and right lenses 72 (and left and right lenses 76) based on information from sensors in device 10 (e.g., based on a measured interpupillary distance gathered using gaze trackers 86).

During the operations of block 104, an iris scanner, fingerprint sensor, input-output devices that gather username and password information, or other components may be used in authenticating the user. The user may, for example, be directed to supply a username and password so that control circuitry 12 can establish a communications link with an online service that provides media content (block 108). If the user is not authenticated by control circuitry 12 (e.g., if the user' username and password or other credentials (biometric information, etc.) are not authenticated, control circuitry 12 can, during the operations of block 110, prevent the user from accessing the online service, selectively block content, and/or take other suitable action. If desired, the user may be allowed to override the authentication process at block 110 and/or additional authentication techniques may be used in scenarios in which the user fails authentication during the operations block 106.

In some configurations of device 10, lenses 76 may carry user information (e.g., user game preferences, user movie preferences, etc.). In these configurations, control circuitry 12 can refrain from decoding this information until the user has been authenticated during the operations of block 106 and an appropriate decryption key has been obtained (e.g., the user's password).

In some embodiments, user information is stored by control circuitry 12. The user information may include information on a user's eye glasses prescription (e.g., a required optical prescription strength). The information stored in lenses 76 may include information on the optical prescription strength of lenses 76. After determining the user of device 10 and retrieving the user's stored prescription from control circuitry 12, control circuitry 12 may compare this retrieved user prescription information with the prescription of lenses 76 to determine if there is a satisfactory match. In the event that the prescription of lenses 76 does not match the user's prescription, control circuitry 12 may use display 14 and/or other output circuitry to issue a visible and/or audible alert for the user and may, if desired, decline to display content on display 14.

In scenarios in which optical aberration information is included in the information stored in lenses 76 (e.g., information indicating that lenses 76 have a particular amount of barrel distortion, pincushion distortion, spherical aberration, chromatic aberration, etc.), control circuitry