Patent Publication Number: US-2023139001-A1

Title: Ophthalmic device having adjustable filtering properties

Description:
FIELD OF THE INVENTION 
     The invention relates to ophthalmic devices having adjustable filtering properties, such as hue or Chroma properties. 
     BACKGROUND ART 
     American patent application US 2018/0017780 discloses an ophthalmic device provided with a colour changeable optical filter which is configured so that hue or Chroma of the light transmitted through the optical filter can be changed. 
     In an embodiment, the filter includes two polarizers, one of which being rotatable for changing hue or Chroma of the light transmitted through the optical filter. 
     In another embodiment, the colour changeable optical filter includes two polarizing films and a liquid crystal polarization rotator interposed between the polarizing films. The liquid crystal polarization rotator has two states which depends on the supplying or not of a voltage thereto. When no voltage is supplied to the liquid crystal polarization rotator, a polarization plane of light at the output of one of the two polarizing film is rotated (active state); while when the voltage is supplied to the liquid crystal polarization rotator, the polarization plane of light at the output of the polarizing film is not rotated (inactive state). In the active state, the rotation of the polarization plane allows changing hue or Chroma of the light transmitted through the optical filter; while in the inactive state, hue or Chroma are not changed. 
     SUMMARY OF THE INVENTION 
     The invention is directed to an ophthalmic device having adjustable filtering properties, such as hue or Chroma properties, which is improved and optimized and which is further convenient, simple, economic and easy to manufacture. 
     The invention accordingly provides an ophthalmic device having adjustable filtering properties, comprising at least one first polarizer, at least one second polarizer which is fixed relative to said first polarizer, and at least one adjustable filtering member located between said first and second polarizers and configured to rotate a polarization plane of light received from said first polarizer and propagating towards said second polarizer; wherein said adjustable filtering member is configured to admit a plurality of active states, in each of which said adjustable filtering member rotates the polarization plane according to a respective and predetermined angle. 
     In other words, the adjustable filtering member is able to rotate the polarization plane of light received from the first polarizer and propagating towards the second polarizer, in a plurality of positions in order to adjust filtering properties of the ophthalmic device, such as hue or Chroma. 
     Each active state is defined by a predetermined and respective angle of rotation which is distinct from the other angles of the other active states. Said otherwise, there are as much angles of rotation of the polarization plane as active states. 
     A user of the ophthalmic device may thus adjust the filtering properties by selecting the active state of the adjustable filtering member which rotates the polarization plane as he may wish. 
     The fact that the first and second polarizers are fixed to each other makes easier the selection by the user of the needed active state amongst a plurality of active states. 
     According to advantageous and convenient features, the adjustable filtering member of the ophthalmic device is a half-wave plate. 
     Using a half-wave plate as adjustable filtering member allows to provide with a large number of active states having different angles of rotation which extend in a large range. 
     In particular, the predetermined angle by which is rotated the polarization plane of light is twice the angle made between the polarization plane of light received from the first polarizer and an axis characteristic of the half-wave plate (for instance the fast or slow axis of the half-wave plate). In other words, if the axis characteristic of the half-wave plate is rotated by an angle equal to θ with respect to the polarization axis of the first polarizer, the polarization plane of light received from the first polarizer and propagating towards the second polarizer is rotated by an angle equal to 2θ. 
     According to further advantageous and convenient features:
         said ophthalmic device comprises at least a frame in which are fixedly mounted said at least one first and at least one second polarizers;   said frame is a spectacle frame having two bearing portions into each of which is at least partially mounted one said first polarizer, one said second polarizer and one said adjustable filtering member;   said frame comprises a synchronization member connected to said two bearing portions and configured to synchronize the selected active states of said adjustable filtering members which are mounted in said two bearing portions, so that the corresponding angles of rotation of the respective polarization planes are similar;   said at least one adjustable filtering member is rotatable with respect to said first and second polarizers;   said active states are selected by rotating said at least one adjustable filtering member according to distinct angles of rotation;   said ophthalmic device comprises at least an actuator configured for rotating said at least one adjustable filtering member, said actuator extending from a carrier of said ophthalmic device which is fixed to and at least partially surrounds said at least one adjustable filtering member, or is laminated on said at least one adjustable filtering member;   said at least one second polarizer has a polarizing axis which is oriented parallel or perpendicular to a polarizing axis of said first polarizer;   said adjustable filtering member is configured to rotate said polarization plane of light received from said at least one first polarizer on a range of 45° between 0° and 45°, and preferably on a range of 30° between 7.5° and 37.5°;   said adjustable filtering member is a half-wave plate that is flat or curved;   said ophthalmic device comprises at least one ophthalmic lens on which is fixed or which is integrally formed with at least one of said first and second polarizers;   said at least one ophthalmic lens has corrective optical properties;   said at least one adjustable filtering member is electrically controlled;   said at least one adjustable filtering member is controlled by applying a predetermined voltage value selected amongst a range of voltage values, each voltage value corresponding to a respective active state and thus a respective predetermined angle of rotation of the polarization plane; and/or   said adjustable filtering properties are configured for varying at least one of darkness, colours, contrast enhancer, and spectral behaviours depending on wavelengths.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The description of the invention now continues with a detailed description of advantageous embodiments given hereinafter by way of non-limiting example and with reference to the appended drawings. In these drawings: 
         FIG.  1    is a perspective and partial view of an ophthalmic device according to the invention, comprising a spectacle frame, two eyeglasses each having adjustable filtering properties and a synchronization member connected to both eyeglasses for synchronizing their filtering properties; 
         FIG.  2    is an exploded view of the ophthalmic device of  FIG.  1   , one of the eyeglasses being missing, the remaining eyeglass comprising—from right to left—a front polarizer, an adjustable filtering member fixed to a carrier and a rear polarizer; 
         FIGS.  3  to  5    schematically illustrate the cooperation between the synchronization member and a variant of the carrier of the adjustable filtering member, the adjustable filtering member being in three distinct active states respectively between which it is rotatable; 
         FIGS.  6  and  7    each schematically illustrate an eyeglass of the ophthalmic device and the resulting filtered light, the adjustable filtering member being in a first active state and in a second active state respectively; 
         FIG.  8    illustrates respective angular positions of a polarization axis of the front polarizer, a polarization axis of the second polarizer and an axis characteristic of the adjustable filtering member one with respect to the others, together with a range of angles of rotation for the axis characteristic of the adjustable filtering member selected as particularly efficient; and 
         FIG.  9    illustrates the variation of transmittance of the eyeglass of the  FIG.  1    as a function of the angle of rotation of the axis characteristic of the adjustable filtering member with respect to the polarization axis of the front polarizer of said eyeglass. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
     The ophthalmic device  10  illustrated on  FIGS.  1  and  2    comprises a spectacle frame  11 , a first eyeglass  12  and a second eyeglass  13 . 
     The frame  11  comprises a first bearing portion  15  configured to receive the first eyeglass  12 , a second bearing portion  16  configured to receive the second eyeglass  13 , and a bridge  17  extending from the first bearing portion  15  to the second bearing portion  16 . 
     The assembly formed by the first bearing portion  15  and the first eyeglass  12  is identical to the assembly formed by the second bearing portion  16  and the second eyeglass  13 , except they are arranged symmetrically. The following description of the first bearing portion  15  and the first eyeglass  12  therefore applies mutatis mutandis to the second bearing portion  16  and the second eyeglass  13 . 
     The bearing portion  15  has a generally annular shape and has an inner surface  21  defining an inner space  22  configured to at least partially receive the first eyeglass  12 . The bearing portion  15  here entirely surrounds the first eyeglass  12 . The bearing portion  15  has an outer surface  31  that is opposite to the inner surface  21 . 
     The first eyeglass  12  is configured to have adjustable filtering properties. 
     Since it is desirable here that the first eyeglass  12  and the second eyeglass  13  have the same filtering properties at the same time, the ophthalmic device  10  comprises a synchronizing system configured to synchronize their filtering properties. The synchronizing system comprises here a synchronization member  14  connected to the bearing portions  15  and  16 . This will be described in more details later. 
     The first eyeglass  12  comprises a first polarizer  18 , a second polarizer  19  which is fixed relative to the first polarizer  18 , and an adjustable filtering member  20  located between the first and second polarizers  18  and  19 . 
     The adjustable filtering member  20  is here a half-wave plate. 
     The first polarizer  18  and the second polarizer  19  are each fixedly mounted in the first bearing portion  15  of the frame  11 . In particular, the first and the second polarizers  18  and  19  are not free to rotate with respect to the first bearing portion  15 . 
     In contrast, the adjustable filtering member  20  is here mounted in the bearing portion  15  so as to be free to rotate about an axial direction  28  according to which the first polarizer  18 , the adjustable filtering member  20  and the second polarizer  19  are aligned. 
     The adjustable filtering member  20  is thus rotatable with respect to the first and second polarizers  18  and  19 . 
     The first polarizer  18  is situated remote to the eye of a wearer (not shown) of the ophthalmic device  10  and is thus a front polarizer, while the second polarizer  19  is situated close to the eye of a wearer of the ophthalmic device  10  and is thus a rear polarizer. 
     Generally speaking, in the present memorandum the “rear” and “front” terms are to be understood as meaning closest to the eye of the user and remote to the eye of the user respectively. 
     In  FIGS.  1  and  2   , the eye of the user (not shown) is situated to the left of the frame  11 . 
     The first polarizer  18  is here integrally formed with a disc-shaped element that has a substantially constant thickness. The first polarizer  18  has a peripheral side surface  23  that is configured to cooperate with the inner surface  21  of the bearing portion  15  for fixedly mounting the first polarizer  18  in the bearing portion  15 , here by snap-fitting. 
     The disc-shaped element forming the first polarizer  18  here does not have corrective properties. 
     The second polarizer  19  is here integrally formed with an ophthalmic lens of the ophthalmic device  10 . The second polarizer  19  has a peripheral side surface  26  that is configured to cooperate with the inner surface  21  of the bearing portion  15  for fixedly mounting the second polarizer  19  in the bearing portion  15 . 
     The ophthalmic lens forming the second polarizer  19  here has corrective optical properties. In particular, the second polarizer  19  may have a front surface  25  and a rear surface  27 , situated on either sides of the peripheral side surface  26 , at least one of which is curved such that the second polarizer  19  has a varying thickness. 
     The adjustable filtering member  20  comprises here a polycarbonate film of 60 μm thickness configured to provide a half-wave plate function. The adjustable filtering member  20  here further comprises a cellulose triacetate (TAC) film of 190 μm thickness on which the polycarbonate film is laminated. 
     The first eyeglass  12  comprises here a carrier  29  that at least partially surrounds the adjustable filtering member  20  and to which is fixed the adjustable filtering member  20 . The assembly formed by the carrier  29  and the adjustable filtering member  20  is here generally disc-shaped. 
     Here, the adjustable filtering member  20  is flat, that is to say not curved. In variant, the adjustable filtering member  20  may be curved, for instance for matching the curvature of the front surface  25  of the second polarizer  19 , this being favourable to compactness of the ophthalmic device. 
     The carrier  29  is mounted in the bearing portion  15  so as to be free to rotate about the axial direction  28 , thereby rotating the adjustable filtering member  20 . 
     The carrier  29  here comprises a ring  34  of generally circular shape that here entirely surrounds the adjustable filtering member  20 . 
     The carrier  29  further comprises an elongated rib  33  that projects externally from the ring  34 , that is to say in a direction opposite to the adjustable filtering member  20 . The rib  33  here projects radially from the generally circular ring  34  and extends longitudinally parallel to the ring  34 . 
     The inner surface  21  of the bearing portion  15  has an annular recess  24  of generally circular shape configured to receive at least a portion—here a peripheral portion—of the carrier  29  and to form a sliding guide for the carrier  29  when the latter is rotated in the bearing portion  15 . 
     The bearing portion  15  further comprises an elongated opening  35  that surrounds the inner space  22 , leading both through the inner surface  21 , into the recess  24 , and through the outer surface  31 . 
     The elongated opening  35  is here generally located to the side that is closest to the mouth of the wearer of the ophthalmic device  10 . 
     The elongated opening  35  is configured to receive the elongated rib  33  and to form a sliding guide for the rib  33  when the carrier  29  is rotated. The opening  35  is further configured such that the elongated rib  33  is accessible to the wearer of the ophthalmic device  10 , the rib  33  thereby forming an actuator that extends from the carrier  29  and that is configured for rotating the adjustable filtering member  20 . 
     The rib  33  and the opening  35  are further configured to define predetermined angular positions of the carrier  29  and thus of the adjustable filtering member  20 . More specifically, the carrier  29 , together with the adjustable filtering member  20 , may be rotated from an extreme position in which the rib  33  abuts against an end of the elongated opening  35  and another extreme position in which the rib  33  abuts against the opposite end of the elongated opening  35 , said ends being longitudinally opposite to each other. 
     Here, the length of the elongated opening  35  is such that the angular range by which the carrier  29  and the adjustable filtering member  20  may be rotated is about 30°. 
     The carrier  29  further comprises a notch  37  formed into the ring  34  and extending transversally to the ring  34 . The notch  37  is here located to the side that is closest to the forehead of the wearer of the ophthalmic device  10 . In other words, the notch  37  is generally situated radially opposite to the rib  33  forming the actuator. 
     The bearing portion  15  further comprises a mounting hole  36 , that is here located to the side that is closest to the forehead of the wearer of the ophthalmic device  10 . 
     The mounting hole  36  and the notch  37  are configured for connecting the synchronization member  14  to the first bearing portion  15  and to its carrier  29 ; and the corresponding mounting hole  36  and the corresponding notch of the second bearing portion  16  are configured for connecting the synchronization member  14  to the second bearing portion  16  and to the carrier of the second bearing portion  16 . 
     The synchronization member  14  here comprises a bar  38  and two pins  39  situated at a respective ends of the bar  38  and extending transversally to the bar  38 . 
     The mounting hole  36  of the first bearing portion  15  and the corresponding mounting hole  36  of the second bearing portion  16  are configured to form a sliding guide for the bar  38  that is at least partially received in each mounting hole  36 . 
     The bar  38  here extends generally parallel to the bridge  17  and is located closest to the forehead of a wearer of the ophthalmic device  10  than is the bridge  17 . 
     Each pin  39  is configured to fit into the notch  37  of the carrier  29  of a respective of the first and second eyeglasses  12  and  13 . 
     The synchronization member  14  is thereby configured such that a rotating movement of the carrier  29  in the first bearing portion  15  is replicated by the other carrier in the second bearing portion  16 , and reciprocally. 
     It should be noted here that the synchronization member  14  is configured to look like another bridge extending between first and second bearing portions  15  and  16 , such that the frame  11  looks like a “double bridge” frame that is a common design in eyewear industry. 
     It should further be noted that the synchronization member  14  also forms an actuator for rotating the carriers  29  and thus the adjustable filtering members  20 , such that the ribs  33  may be optional. 
       FIGS.  3  to  5    schematically illustrate the cooperation between the synchronization member  14  and a carrier  129  that is a variant of the carrier  29  for the adjustable filtering member  20 . 
     The carrier  129  is similar to the carrier  29  except that the ring is replaced by a generally circular disc-shaped element  134  onto which the film configured to provide the half-wave plate function is laminated. Only a portion of the carrier  129  is shown on  FIGS.  3  to  5   . 
     The notch  37  is replaced by a hole  137  extending radially from a peripheral side  40  of the carrier  129 . 
       FIGS.  3  and  5    respectively illustrate the above mentioned extreme positions between which the adjustable filtering member  20  may be rotated, which positions are angularly spaced by 30°; and  FIG.  4    illustrate an intermediate position between the two extreme positions, that is to say angularly spaced by 15° from each extreme position. 
     In each of  FIGS.  3  to  5   , the position of the hole  137  is shown for the two extreme positions and for the intermediate position of the adjustable filtering member  20 , the hole  137  being drawn in full line at its current position and in broken line at the two other positions. 
     As explained in the following, it is possible to adjust the filtering properties of the first eyeglass  12  by rotating the adjustable filtering member  20  according to distinct angles of rotation, each corresponding to an active state of the adjustable filtering member  20 . 
     The adjustable filtering member  20  is thus configured to admit a plurality of active states that are selected by rotating the adjustable filtering member  20  according to distinct angles of rotation, each corresponding to a respective active state. 
     The filtering properties of the first eyeglass  12  are defined by the cooperation of the adjustable filtering member  20  with the first polarizer  18  and the second polarizer  19 . 
     As shown on  FIGS.  6  to  8   , the first polarizer  18  has a first polarization axis  41  and the second polarizer  19  has a second polarization axis  42  that is oriented transversely to the polarization axis  41  of the first polarizer  18 , here perpendicularly. 
     Since the adjustable filtering member  20  is a half-wave plate, it is configured to rotate the polarization plane of light received from the first polarizer  18  and propagating towards the second polarizer  19 . 
     In particular, the predetermined angle by which is rotated the polarization plane of light is twice the angle made between the polarization plane of light received from the first polarizer  18  and an axis  43  characteristic of the half-wave plate (for instance the fast or slow axis of the half-wave plate). In other words, if the axis  43  characteristic of the half-wave plate is rotated by an angle equal to θ with respect to the polarization axis  41  of the first polarizer  18 , the polarization plane of light received from the first polarizer  18  and propagating towards the second polarizer  19  is rotated by an angle equal to 2θ. 
     The angle θ between the axis  43  characteristic of the half-wave plate and the polarization axis  41  of the first polarizer  18  here defines an active state that the adjustable filtering member  20  is configured to admit. In each of the plurality of active states, the adjustable filtering member  20  rotates the polarization plane of light received from the first polarizer  18  according to a respective and predetermined angle, here an angle equal to 2θ. 
     The properties of the light transmitted by the eyeglass  12 —that is to say the resulting filtered light—will then depend on the orientation of the polarization plane of light received from the adjustable filtering member  20  with respect to the polarization axis  42  of the second polarizer  19 . 
       FIGS.  6  and  7    each schematically illustrate the eyeglass  12  of the ophthalmic device  10  and the resulting filtered light, the adjustable filtering member  20  being in a first active state (denoted  1  on  FIG.  6   ) and in a second active state (denoted  2  on  FIG.  7   ) respectively. 
     On  FIG.  6   , the polarization plane of light received from the adjustable filtering member  20  is more parallel to the polarization axis  42  than in  FIG.  7    such that more light is transmitted when the adjustable filtering member  20  is in the first active state ( FIG.  6   ) than when the adjustable filtering member  20  is in the second active state ( FIG.  7   ). The eyeglass  12  therefore appears darker on  FIG.  7    than on  FIG.  6   . 
     It should be noted that rotating the adjustable filtering member  20  by an angle of 45° will result in a rotation of 90° of the polarization plane of light received from the first polarizer  18 . In other words, a range from 0° to 45° for rotating the adjustable filtering member  20  is sufficient to pass this polarization plane from an orientation substantially perpendicular to the polarization axis  42  to an orientation substantially parallel to the polarization axis  42 , corresponding respectively to the darker and the brighter appearances of the eyeglass  12 . 
     Accordingly, the adjustable filtering member may be configured to rotate the polarization plane of light received from the first polarizer  18  on a range of angles of rotation of 45° between 0° and 45°, such angles being between the polarization axis  41  of the first polarizer  18  and the axis  43  characteristic of the half-wave plate. 
     In the above described embodiment, the adjustable filtering member  20  is configured to rotate the polarization plane of light received from the first polarizer  18  on a preferred range of angles of rotation of 30° between 7.5° and 37.5°, such angles being between the polarization axis  41  of the first polarizer  18  and the axis  43  characteristic of the half-wave plate. 
     This preferred range of angles of rotation is diagrammatically shown on  FIG.  8    with the respective angular positions of the polarization axis  41  of the first polarizer  18 , the polarization axis  42  of the second polarizer  19  and the axis  43  characteristic of the half-wave plate forming the adjustable filtering member  20 . Here the axis  43  characteristic of the half-wave plate is the slow axis. Line  44  on  FIG.  8    corresponds to the angle of rotation of 7.5° to which is associated one of the above mentioned extreme positions illustrated on  FIGS.  3  and  5   , and line  45  on  FIG.  8    corresponds to the angle of rotation of 37.5° to which is associated the other of the above mentioned extreme positions illustrated on  FIGS.  3  and  5   . The axis  43  is in the middle of the range extending from 7.5° and 37.5°, that is to say the angle of rotation of 22.5° to which is associated the above mentioned intermediate position illustrated on  FIG.  4   . 
       FIG.  9    illustrates the variation of transmittance of the first eyeglass  12  as a function of the angle of rotation of the axis  43  characteristic of the adjustable filtering member  20  with respect to the polarization axis  41  of the front polarizer  18 . 
     As shown on  FIG.  9   , the preferred range of angles of rotation is optimized as it is relatively narrow (30°) while the associated variation of transmittance (dark aspect of the eyeglass  12 ) is relatively high, here about 86% of the entire possible range of transmittance (varying on the ordinate axis from 0 for a total extinction to 1 for a maximum transmittance). 
     It should be noted that the entire possible range of transmittance of the first eyeglass depends in particular on the degree of polarization, or polarization efficiency, of the front and rear polarizers  18  and  19 . For a given polarizer receiving a polarized beam of light, the polarization efficiency P can be defined by P=(T1−T2)/(T1+T2), where T1 can be the maximum transmission of the polarizer and occurs when the axis of the polarizer is parallel to the plane of polarization of the incident polarized beam and T2 can be the minimum transmission of the polarizer and occurs when the axis of the polarizer is perpendicular to the plane of polarization of the incident polarized beam. 
       FIG.  9    illustrates the variation of transmittance of the first eyeglass in the case where the front polarizer  18  and the rear polarizer  19  each have a polarization efficiency equal to 100%, i.e. with a maximum transmission T1 of 100% and a minimum transmission T2 of 0%, and have their respective polarisation axis  41  and  42  that are disposed perpendicular one another.
         Maximum of transmission of the first eyeglass  12  (illustrated by “1” on the ordinate axis of the  FIG.  9   , corresponding to a transmission of 50% of the incoming light, and corresponding to an angle θ equals to 45°)       

     In the above mentioned configuration, when the half-wave plate  20  is in the active state wherein the angle θ equals to 45°, the polarization plane of light received from the front polarizer  18  is rotated according to an angle of 90°. The front polarizer  18  with its maximum transmission T1 of 100% of the incoming light, transmits only a component equivalent to 50% of said incoming light since this light is here non-polarized. The rear polarizer  19 , with its maximum transmission T1 of 100% of the light outgoing the half-wave plate  20 , transmits 100% of said light since this light has a polarization plane parallel to the polarisation axis  42  of said rear polariser  19 . As a result, the transmission of the first eyeglass  12  in this configuration is 50% of the incoming non-polarized light.
         Minimum of transmission of the first eyeglass  12  (illustrated by “0” on the ordinate axis of the  FIG.  9   , corresponding to a transmission of 0% of the incoming light, and corresponding to an angle θ equals to 0°)       

     In the above mentioned configuration, when the half-wave plate  20  is in the active state wherein the angle θ equals to 0°, the polarization plane of light received from the front polarizer  18  is not rotated, and since the front and rear polarizers have their respective polarisation axis perpendicular one another the first eyeglass  12  does not transmit any incoming light.
         Intermediate transmission of the first eyeglass  12         

     When the half-wave plate  20  is in any active state different from the above described ones providing the maximum and minimum transmittances, the transmittance of the first eyeglass  12  takes an intermediate corresponding value as illustrated on the  FIG.  9   . 
     Accordingly, the entire possible range of transmittance of the first eyeglass here goes from “0” (total extinction) to “1” (maximum transmittance i.e. transmission of 50% of the non-polarized incident light). 
     In a variant, the first polarizer and the second polarizer may be selected such that their respective polarization efficiency is different from 100%. For instance the first and the second polarizer may have a polarization efficiency equal or close to 83.5% with a maximum transmission T1 of 83.5% and a minimum transmission T2 of 0%. In such variant, for an angle θ varying between θ=11° and θ=34°, the corresponding entire possible range of transmittance goes respectively from 5% (corresponding to 0.14 of transmission on the ordinate axis of the  FIGS.  9   , and to θ equals to 11°) to 30% (corresponding to 0.86 on the ordinate axis of the  FIGS.  9   , and to θ equals to 34°). 
     In the above embodiment described in reference to  FIGS.  1  to  9   , the carriers  29  and  129  each have a generally circular shape. In a variant, the carrier of the adjustable filtering member may have a shape that is different from generally circular. In such case, the annular recess may be configured such that no part of the peripheral portion of the carrier escapes from the annular recess regardless of the angle by which the carrier is rotated. In particular, the minimal depth required for the annular recess at any location thereof may be determined. In this respect, it should be noted that such minimal depth not only depends on the shape of the carrier but also on the range of rotation angles required for the carrier. In particular, the smaller the range of rotation angles, the smaller the minimal depth required. Here, since it is sufficient that the range of angles of rotation of the carrier be of 45°, or preferably of 30°, the minimal depth of the annular recess may be relatively small, which is favourable to the compactness of the mounting portion. 
     It should be noted that in the above embodiment, the first polarizer  18  is mounted in the spectacle frame  11  such that its polarization axis  41  is oriented according to a chin-forehead direction with respect to the wearer of the ophthalmic device  10 . In this manner, the polarization axis  41  is most of the time oriented generally vertically when the ophthalmic device  10  is worn, so as to filter reflected light from the environment that is mainly horizontally polarized. 
     In a variant, the first polarizer may be mounted in the spectacle frame such that its polarization axis is oriented according to a left temple-right temple direction with respect to the wearer of the ophthalmic device. In this manner, the polarization axis is most of the time oriented generally horizontally when the ophthalmic device is worn. The polarization axis of the second polarizer may be oriented perpendicularly to the polarization axis of the first polarizer and the filtering of the polarized reflected light may thus be adjusted with the adjustable filtering member. 
     In the above described embodiment, the ophthalmic device  10  is configured such that the adjustable filtering properties are configured for varying the darkness of transmitted light, but in variants the filtering properties may be configured for varying at least one of darkness, colours, contrast enhancer, spectral behaviours depending on wavelengths and polarization of transmitted light. 
     Of course, in the above embodiment in which the ophthalmic device  10  comprises two eyeglasses  12  and  13  each mounted in a respective bearing portion  15  and  16 , because the synchronization member  14  ensures that a rotating movement of the carrier  29  in the first bearing portion  15  is replicated by the other carrier in the second bearing portion  16  and reciprocally, the synchronization member  14  is configured to synchronize the selected active states of the respective adjustable filtering members  20 , so that the corresponding angles of rotation of the respective polarization planes of light received from the respective first polarizers  18  are similar. 
     In a variant, the adjustable filtering member is an electrically controlled half-wave plate. More specifically, the adjustable filtering member may be controlled by applying a predetermined voltage value selected amongst a range of voltage values, each voltage value corresponding to a respective active state and thus a respective predetermined angle of rotation of the polarization plane. In addition, the adjustable filtering member may be fixed with respect to the frame in which it is mounted. 
     In another variant, the adjustable filtering member may be different from a half-wave plate, for instance a linear liquid crystal polarization rotator. 
     In variants that are not illustrated:
         only one of the first and second eyeglasses has adjustable filtering properties;   the first and/or second bearing portions partially surrounds the eyeglass;   the polarization axis of the second polarizer is substantially parallel to the polarization axis of the first polarizer;   the carrier may have at least two radially opposite portions each configured to cooperate with the inner surface of the bearing portion, and the inner surface of the bearing portion may have a shape including at least two radially opposite arcuate portions each configured to cooperate with a respective of the radially opposite portions of the carrier to form a sliding guide for the carrier;   the ophthalmic device is different from spectacles, for instance binoculars or a telescope;   the first and/or second polarizers is different from a polarizer that is integrally formed with disc-shaped element/ophthalmic lens, for instance the first and/or second polarizers comprise a film configured to provide a polarizing function that is laminated on a disc-shaped element/ophthalmic lens; and/or   the ophthalmic lens is not associated to the rear polarizer but to the front polarizer;       

     It should be noted more generally that the invention is not limited to the examples described and represented.