Optical scanning device comprising a main lens and an auxiliary lens

An optical player includes an optical scanning device. The scanning device includes an optical lens system for focusing a light beam into a scanning spot on a track of an information carrier. The scanning device includes a first actuator for displacing the lens system parallel to an optical axis for focusing the light beam on the information carrier. The lens system includes a main lens or objective lens and an auxiliary or solid immersion lens, providing the lens system with a large numerical aperture, so that the scanning device is suitable for scanning information carriers with a high information density, such as, for example, high density compact discs. The auxiliary lens is secured in a fixed position to a housing of the lens system, while the main lens is suspended in the housing in a direction parallel to the optical axis by an elastically deformable mounting unit. The lens system includes a second actuator for moving the main lens relative to the auxiliary lens in a direction parallel to the optical axis for compensating for spherical aberration in a transparent protection layer of the information carrier. Thus, the necessary power of the first actuator is limited considerably.

FIELD OF THE INVENTION
 The invention relates to the field of optical scanning of high density
 disk-like information carriers.
 BACKGROUND OF THE INVENTION
 The invention relates to an optical scanning device for scanning an
 information track of an optically scannable information carrier, which
 scanning device includes a radiation source, an optical lens system with
 an optical axis for focusing a radiation beam supplied, in operation, by
 the radiation source into a scanning spot on the information carrier, and
 a first actuator for moving the lens system parallel to the optical axis,
 the lens system being provided with a main lens, an auxiliary lens, and a
 second actuator for moving the main lens and the auxiliary lens relative
 to each other.
 The invention further relates to an optical lens system which can suitably
 be used in an optical scanning device in accordance with the invention.
 The invention also relates to an optical player including a table which can
 be rotated about an axis of rotation, an optical scanning device for
 scanning an information track of an optically scannable information
 carrier which can be placed on the table, and a displacement device by
 means of which the scanning device can be moved, in operation, mainly in a
 radial direction relative to the axis of rotation.
 An optical scanning device and an optical player of the types mentioned in
 the opening paragraphs are known from U.S. Pat. No. 5,712,842. The main
 lens of the optical lens system of the known optical scanning device is an
 objective lens, while the auxiliary lens is a relatively small, so-called
 solid immersion lens which is arranged between the objective lens and the
 information carrier to be scanned. By using the auxiliary lens, the lens
 system of the known scanning device has a relatively large numerical
 aperture, so that a relatively small scanning spot on the information
 carrier to be scanned is obtained. By virtue thereof, the known scanning
 device can suitably be used to scan information carriers having relatively
 small elementary information characteristics, that is information carriers
 having a relatively high information density, such as a high-density CD.
 By means of the first actuator of the known scanning device, the main lens
 and the auxiliary lens are jointly moved parallel to the optical axis, so
 that the scanning spot can be focused on the information layer of the
 information carrier. By means of the second actuator of the known scanning
 device, the auxiliary lens is moved relative to the main lens in a
 direction parallel to the optical axis, so that a spherical aberration of
 the radiation beam in a transparent protective layer of the information
 carrier present between the information layer and the scanning device can
 be corrected.
 The above citation is hereby incorporated herein in whole by reference.
 SUMMARY OF THE INVENTION
 The inventors have recognized that a drawback of the known optical scanning
 device and the known optical player is that, as a result of the relatively
 large mass of the main lens, the first actuator must supply relatively
 large accelerating forces to correct high-frequency focusing errors which
 occur as a result of surface deviations present in the information layer
 of the information carrier to be scanned, in the direction of the
 information track to be scanned. As a result, the first actuator must have
 a relatively high power.
 It is an object of the invention to provide an optical scanning device and
 an optical player of the types mentioned in the opening paragraphs, in
 which the accelerating forces, to be supplied by the first actuator, for
 correcting high-frequency focusing errors are limited, so that the
 necessary power of the first actuator is limited.
 In the optical scanning device in accordance with the invention the
 auxiliary lens is secured in a fixed position to a housing of the lens
 system, which housing can be moved parallel to the optical axis by the
 first actuator, while the main lens, viewed parallel to the optical axis,
 is elastically suspended in the housing by means of an elastically
 deformable mounting unit, the main lens being movable relative to the
 housing by the second actuator in a direction parallel to the optical
 axis.
 In operation, by displacements of the lens system parallel to the optical
 axis, both low-frequency focusing errors which have a relatively large
 amplitude and occur as a result of an oblique position of the information
 carrier to be scanned relative to the optical axis and/or by unevenness of
 the information carrier, and high-frequency focusing errors which have a
 relatively small amplitude and occur as a result of surface deviations
 present in the information layer of the information carrier in the
 direction of the information track to be scanned, must be corrected. Since
 the acceleration of the lens system is proportional to the amplitude of
 the focusing errors to be corrected and proportional to the square of the
 frequency of the focusing errors to be corrected, the accelerations of the
 lens system necessary to correct the high-frequency focusing errors are
 relatively large relative to the accelerations of the lens system
 necessary for correcting the low-frequency focusing errors. The
 elastically deformable mounting unit has a stiffness which, viewed
 parallel to the optical axis, is such that the main lens substantially
 completely follows the displacements of the lens system necessary to
 correct the relatively large low-frequency focusing errors, and
 substantially does not follow the displacements of the lens system
 necessary to correct the relatively small high-frequency focusing errors.
 In this manner it is achieved that the total mass, which is to be
 displaced by the first actuator to correct the small high-frequency
 focusing errors, is limited to mainly the mass of the housing of the lens
 system and the mass of the auxiliary lens, so that the accelerating forces
 for correcting the high-frequency focusing errors, which forces are to be
 supplied by the first actuator, and the necessary power of the first
 actuator are limited. The elastically deformable mounting unit also serves
 as a bearing of the main lens in the housing of the lens system.
 In a particular embodiment of an optical scanning device in accordance with
 the invention, the mounting unit of the lens system includes two mounting
 elements which, viewed parallel to the optical axis, are arranged at some
 distance from each other and extend transversely to the optical axis, each
 mounting element, viewed parallel to the optical axis, being elastically
 deformable and, viewed at right angles to the optical axis, being mainly
 undeformable. By using the two mounting elements, viewed at right angles
 to the optical axis, a very rigid bearing of the main lens relative to the
 housing is achieved. By the co-operation between the two mounting
 elements, in addition, tilting of the main lens relative to the housing
 about tilting axes directed at right angles to the optical axis is
 precluded. In this manner, undesirable displacements of the main lens
 relative to the auxiliary lens, at right angles to the optical axis, and
 undesirable tilting of the main lens relative to the auxiliary lens about
 tilt axes directed at right angles to the optical axis are precluded,
 while displacements of the main lens relative to the auxiliary lens in a
 direction parallel to the optical axis are possible, thereby elastically
 deforming both mounting elements.
 In a further embodiment of an optical scanning device in accordance with
 the invention is characterized in that the mounting elements are each
 provided with a first, substantially ring-shaped part which is secured to
 the housing, and a second substantially ring-shaped part which is secured
 to the main lens, the ring-shaped parts of a first one of the mounting
 elements being interconnected by at least three bendable bridges extending
 in a plane transverse to the optical axis and being arranged at regular
 distances from each other, while the ring-shaped parts of a second one of
 the mounting elements are interconnected by at least two bendable bridges
 extending in a plane transverse to the optical axis. If the first mounting
 element has three bendable bridges and the second mounting element has two
 bendable bridges, then a so-called statically determined, that is
 substantially stress-free suspension of the main lens in the housing is
 achieved, the main lens being displaceable exclusively parallel to the
 optical axis. If a larger number of bendable bridges is used, the
 suspension of the main lens in the housing is not statically determined,
 but the main lens can still be displaced in a direction parallel to the
 optical axis.
 In a still further embodiment of an optical scanning device in accordance
 with the invention, the first mounting element and the second mounting
 element each includes three bendable bridges mutually arranged at regular
 interspaces. In this further embodiment, two identical mounting elements
 can be used, so that the construction of the lens system of the optical
 scanning device is simplified.
 In a particular embodiment of an optical scanning device in accordance with
 the invention, the bendable bridges of the mounting elements each includes
 a uniformly bendable spoke which extends substantially in a tangential
 direction relative to the optical axis. By using the uniformly bendable
 spokes, a simple and robust construction of the mounting elements is
 achieved.
 In a further embodiment of an optical scanning device in accordance with
 the invention, the bendable bridges of the mounting elements each include
 a relatively rigid strip which extends mainly in a tangential direction
 relative to the optical axis and is connected, via two flexible joints, to
 the two ring-shaped parts of the relevant mounting element. By using the
 strips and flexible joints, the mounting elements can be manufactured in a
 simple manner by providing a number of incisions.
 In a particular embodiment of an optical scanning device in accordance with
 the invention, the housing of the lens system includes three parts which
 are fixed relative to each other, the auxiliary lens being secured to a
 first one of the three parts, the first mounting element being secured to
 a second one of the three parts, and the second mounting element being
 secured to a third one of the three parts. By moving the three parts
 relative to each other by means of a manipulator, during the manufacture
 of the lens system, the main lens and the auxiliary lens can be aligned
 relative to each other. By moving the second and the third part over equal
 distances relative to the first part in an equal direction at right angles
 to the optical axis, the main lens and the auxiliary lens can be centered
 relative to each other. By moving the second and the third part over equal
 distances, in opposite directions, at right angles to the optical axis,
 relative to the first part, the main lens and the auxiliary lens can be
 directed so as to be parallel to each other. After aligning the main lens
 and the auxiliary lens relative to each other, the three parts of the
 housing are fixed relative to each other.
 In a further embodiment of an optical scanning device in accordance with
 the invention, the second actuator belonging to the lens system is
 arranged, viewed parallel to the optical axis, between the two mounting
 elements. In this manner, the available space between the two mounting
 elements is efficiently used, so that a compact construction of the lens
 system is obtained.
 In yet another embodiment of an optical scanning device in accordance with
 the invention, the second actuator is provided with two ring-shaped
 permanent magnets which, viewed parallel to the optical axis, are secured,
 next to one another, to a substantially ring-shaped magnetic closing yoke
 belonging to the housing, and which, relative to the optical axis, are
 magnetized in opposite radial directions, and with two ring-shaped
 electric coils which are secured to a substantially ring-shaped
 non-magnetizable holder of the main lens, the coils, viewed parallel to
 the optical axis, being arranged next to one another, opposite the two
 magnets, and wound in opposite directions. The second actuator thus
 constructed has a favorable ratio between the maximum electromagnetic
 force that can be supplied and the necessary dimensions of the magnets and
 the electric coils. The ring-shaped magnets and coils can be accommodated,
 in a practical manner, in the available space between the two mounting
 elements. By securing the coils to the above-mentioned nonmagnetizable
 holder of the main lens, an undesirable radial magnetic attractive force
 between the magnets and the holder is prevented, so that mechanical loads
 of the mounting elements in radial directions are precluded to the extent
 possible.
 In a particular embodiment of an optical scanning device in accordance with
 the invention, the magnetic closing yoke constitutes the third part of the
 housing. In this manner, a practical and efficient embodiment of the
 magnetic closing yoke of the second actuator is obtained.
 These and other aspects of the invention will be apparent from and
 elucidated with reference to the embodiments described hereinafter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 FIG. 1 schematically shows an optical player in accordance with the
 invention, which includes a table 1 which can be rotated about an axis of
 rotation 3 and can be driven by an electric motor 5 which is secured onto
 a frame 7. On table 1, an optically scannable information carrier 9, such
 as a CD, can be arranged which is provided with a disc-shaped support 11
 and a transparent protective layer 13. A side of the support 11 bordering
 on the protective layer 13 forms an information layer 15 of the
 information carrier 9 on which a spiral-shaped information track is
 present. The optical player further includes an optical scanning device 17
 in accordance with the invention for optically scanning the information
 track of the information carrier 9. Scanning device 17 can be displaced by
 means of a displacement device 19 of the optical player relative to the
 axis of rotation 3 predominantly in two opposite radial directions X and
 X'. To this end, the scanning device 17 is secured to a slide 21 of the
 displacement device 19 which is further provided with a straight guide 23
 provided on the frame 7 and extending parallel to the X direction, over
 which guide the slide 21 is guided in a displaceable manner, and an
 electric motor 25 by means of which the slide 21 can be displaced over the
 guide 23. In operation, an electrical control unit of the optical player,
 not shown in the Figures, controls the motors 5 and 25, causing the
 information carrier 9 to rotate about the axis of rotation 3, and
 simultaneously, the scanning device 17 to be displaced parallel to the
 X-direction, in such a manner that the spiral-shaped information track
 present on the information carrier 9 is scanned by the scanning device 17.
 During scanning, information present on the information track can be read
 by the scanning device 17 or information can be written on the information
 track by the scanning device 17.
 The optical scanning device 17 in accordance with the invention, used in
 the optical player in accordance with the invention is schematically shown
 in FIG. 2. The scanning device 17 is provided with a radiation source 27,
 for example a semiconductor laser, with an optical axis 29. The scanning
 device 17 further includes a radiation beam splitter 31 which includes a
 transparent plate 33 which is arranged at an angle of 45.degree. relative
 to the optical axis 29 of the radiation source 27 and which includes a
 reflective surface 35 facing the radiation source 27. The scanning device
 17 further includes an optical lens system 37 with an optical axis 39 and
 a collimator lens 41 arranged between the radiation beam splitter 31 and
 the lens system 37. The optical axis 39 of the lens system 37 and the
 optical axis 29 of the radiation source 27 include an angle of 90.degree..
 The scanning device 17 further includes an optical detector 43 which,
 relative to the lens system 37, is arranged behind the radiation beam
 splitter 31, the optical detector being of a type which is known per se
 and customarily used. In operation, the radiation source 27 generates a
 radiation beam 45 which is reflected by the reflective surface 35 of the
 radiation beam splitter 31 and focused by the lens system 37 into a
 scanning spot 47 on the information layer 15 of the information carrier 9.
 The radiation beam 45 is reflected by the information layer 15 into a
 reflected radiation beam 49 which is focused on the optical detector 43
 via the lens system 37, the collimator lens 41 and the radiation beam
 splitter 31. For reading information present on the information carrier 9,
 the radiation source 27 generates a continuous radiation beam 45, and the
 optical detector 43 supplies a detection signal which corresponds to a
 series of elementary information characteristics on the information track
 of the information carrier 9, which elementary information characteristics
 are successively present in the scanning spot 47. For writing information
 on the information carrier 9, the radiation source 27 generates a
 radiation beam 45 which corresponds to the information to be written, in
 the scanning spot 47 a series of successive elementary information
 characteristics being generated on the information track of the
 information carrier 9.
 As is also shown in FIG. 2, the scanning device 17 includes a first
 actuator 51 by means of which the lens system 37 can be displaced over
 relatively small distances parallel to the optical axis 39 of the lens
 system 37, and over relatively small distances parallel to the
 X-direction. By displacing the lens system 37 by means of the first
 actuator 51 in a direction parallel to the optical axis 39, the scanning
 spot 47 is focused with a desired degree of accuracy on the information
 layer 15 of the information carrier 9. By displacing the lens system 37 by
 means of the first actuator 51 in a direction parallel to the X-direction,
 the scanning spot 47 is maintained with a desired accuracy on the
 information track to be followed. To this end, the first actuator 51 is
 driven by the above-mentioned control unit of the optical player, which
 receives both a focus-error signal and a track-error signal from the
 optical detector 43.
 The optical lens system 37 used in the optical scanning device 17 is shown
 in detail in FIG. 3 and includes a first lens element 53 and a second lens
 element 55. The first lens element 53 is an objective lens and constitutes
 a main lens of the lens system 37. The second lens element 55 is a
 so-called solid immersion lens, which is arranged between the objective
 lens and the information carrier 9 to be scanned, and which constitutes a
 relatively small auxiliary lens of the lens system 37. By employing, apart
 from the main lens 53, auxiliary lens 55, the lens system 37 has a
 relatively large numerical aperture, so that the scanning spot 47 on the
 information layer 15 of the information carrier 9 is relatively small. As
 a result, the scanning device 17 is suitable for scanning optical
 information carriers having relatively small elementary information
 characteristics, i.e. optical information carriers having a relatively
 high information density, such as a high-density CD. As shown in FIG. 3,
 the auxiliary lens 55 is secured in a fixed position to a housing 57 of
 the lens system 37, which housing 57 is secured to the first actuator 51
 and hence can be displaced parallel to the optical axis 39 of the lens
 system 37 by means of the first actuator 51. The main lens 53 is secured
 to a substantially ring-shaped holder 59 which, viewed parallel to the
 optical axis 39, is elastically suspended in the housing 57 by means of an
 elastically deformable mounting unit 61, which will be described in
 greater detail hereinbelow, said main lens 53 being displaceable, parallel
 to the optical axis 39, relative to the housing 57, thereby elastically
 deforming mounting unit 61. As shown in FIG. 3, the lens system 37 further
 includes a second actuator 63, which will be described in greater detail
 hereinbelow, by means of which the main lens 53 can be displaced, parallel
 to the optical axis 39 of the lens system 37, relative to the housing 57
 and the auxiliary lens 55. By displacing the main lens 53 relative to the
 auxiliary lens 55, in a direction parallel to the optical axis 39, by
 means of the second actuator 63, a spherical aberration of the radiation
 beam 45 in the transparent protective layer 13 of the information carrier
 9 is corrected. Such a spherical aberration is predominantly caused by
 fluctuations in the thickness t of the protective layer 13. The second
 actuator 63 is also driven by the control unit of the optical player,
 which receives an error signal from a sensor of the scanning device 17,
 not shown in the Figures for the sake of simplicity, by means of which
 sensor, for example, the thickness t of the protective layer 13 near the
 scanning spot 47 can be measured.
 As shown in FIG. 3, the mounting unit 61 includes two mounting elements 65,
 67 which, viewed parallel to the optical axis 39, are arranged at a
 distance from each other and extend transversely to the optical axis 39.
 The mounting elements 65, 67, which are identical and shown in detail in
 FIG. 4, are, viewed at right angles to the optical axis 39, substantially
 undeformable and, viewed parallel to the optical axis 39, elastically
 deformable. For this purpose, as shown in FIG. 4, the mounting elements
 65, 67 are each provided with a first, predominantly ring-shaped portion
 69 which is secured to the housing 57 of the lens system 37, and a second,
 predominantly ring-shaped portion 71 which is secured to the holder 59 of
 the main lens 53, ring-shaped portions 69 and 71 being interconnected by
 three bendable bridges 73 which extend in a plane transverse to the
 optical axis 39 and are mutually placed at regular intervals. By using the
 two mounting elements 65, 67, the main lens 53 is given, viewed parallel
 to the optical axis 39, a freedom of displacement, while, viewed at right
 angles to the optical axis 39, a relatively rigid bearing of the main lens
 53 relative to the housing 57 is obtained. The co-operation between the
 two mounting elements 65, 67 additionally provides the mounting unit 61
 with a relatively high tilt resistance about every tilt axis directed
 perpendicularly to the optical axis 39, so that tilting of the main lens
 53 relative to the housing 57 about tilt axes directed at right angles to
 the optical axis 39 is precluded as much as possible. By virtue thereof,
 it is achieved that an alignment of the main lens 53 and the auxiliary
 lens 55 relative to each other, which is obtained during the manufacture
 of the lens system 37, and as a result of which the optical axes of the
 main lens 53 and the auxiliary lens 55 coincide as much as possible, is
 maintained in operation to the extent possible.
 As shown in FIG. 3, the second actuator 63, viewed parallel to the optical
 axis 39, is arranged between the two mounting elements 65, 67 of the
 mounting unit 61, so that the space available between the two mounting
 elements 65, 67 is efficiently used and a compact construction of the lens
 system 37 is obtained. The actuator 63 has two ring-shaped permanent
 magnets 75, 77 which, viewed parallel to the optical axis 39, are arranged
 one beside the other and secured to a substantially ring-shaped closing
 yoke 79, which is made of a magnetizable material and constitutes a
 separate part of the housing 57 of the lens system 37. The actuator 63
 further includes two ring-shaped electric coils 81, 83 which are secured
 to the holder 59 of the main lens 53. Viewed parallel to the optical axis
 39, the coils 81, 83 are also arranged one beside the other, the coil 81
 being arranged opposite the magnet 75 and the coil 83 being arranged
 opposite the magnet 77, while a ring-shaped air gap 85 is present between
 the magnets 75, 77 and the coils 81, 83. As shown in FIG. 3, the magnets
 75, 77 are magnetized, relative to the optical axis 39, in opposite radial
 directions R and R'. The coils 81, 83 are wound in opposite directions
 relative to each other, so that, in operation, an electric current in the
 coil 81 and an electric current in the coil 83 flow in opposite
 directions. In this manner, it is achieved that the electromagnetic forces
 which, in operation, are exerted on the coils 81 and 83 by an interaction
 between a magnetic field of the magnets 75, 77 and the electric current in
 the coils 81, 83 are substantially equally directed. The holder 59 is made
 of a non-magnetizable material, so that the magnets 75, 77 do not exert
 magnetic forces on the holder 59, and mechanical loads on the mounting
 elements 65, 67, which are directed at right angles to the optical axis
 39, are limited as much as possible.
 In operation, during scanning the information track of the information
 carrier 9, both low-frequency focusing errors and high-frequency focusing
 errors occur, which must all be corrected by displacing the lens system 37
 in a direction parallel to the optical axis 39 by means of the first
 actuator 51. The low-frequency focusing errors are caused, for example, by
 an oblique position of the information carrier 9 relative to the axis of
 rotation 3 of the table 1 or by a curvature of the information layer 15 of
 the information carrier 9, and hence the low focusing errors have a
 relatively large amplitude and a frequency corresponding to a rotational
 frequency of the table 1. The high-frequency focusing errors are caused by
 relatively small surface deviations present on the information layer 15 of
 the information carrier 9 in the direction of the information track to be
 scanned, and hence the high-frequency focusing errors have a relatively
 small amplitude and a relatively high frequency. The accelerations of the
 lens system 37, which must be generated by the first actuator 51 in order
 to correct the focusing errors, are substantially proportional to the
 amplitude of the focusing errors to be corrected and proportional to the
 square of the frequency of the focusing errors to be corrected, so that
 the accelerations of the lens system 37, which are to be generated to
 correct the high-frequency focusing errors, are relatively large relative
 to the accelerations of the lens system 37 to be generated for correcting
 the low-frequency focusing errors. Viewed parallel to the optical axis 39,
 the two mounting elements 65 and 67 of the lens system 37 have a
 mechanical rigidity such that the main lens 53 can substantially
 completely follow displacements of the housing 57 of the lens system 37 in
 a direction parallel to the optical axis 39 at a frequency comparable to a
 frequency of the low-frequency focusing errors, and such that the main
 lens substantially cannot follow displacements of the housing 57 of the
 lens system 37 in a direction parallel to the optical axis 39 at a
 frequency comparable to a frequency of the high-frequency focusing errors.
 Such mechanical rigidity of the mounting elements 65 and 67 can be
 achieved, for example, by suitably dimensioning the bendable bridges 73 of
 the mounting elements 65, 67. Thus, the first actuator 51, upon correcting
 the low-frequency focusing errors, displaces the entire lens system 37
 parallel to the optical axis 39, while upon correcting the high-frequency
 focusing errors, mainly, the housing 57, the auxiliary lens 55 and the
 magnets 75, 77 of the second actuator 63 are displaced parallel to the
 optical axis 39. The mass of the main lens 53 constitutes an important
 part of the overall mass of the lens system 37, so that in this manner the
 mass to be displaced by the first actuator 51 upon correcting the
 high-frequency focusing errors is reduced considerably, and hence the
 accelerating forces to be supplied by the first actuator 51 and the
 necessary power of the first actuator 51 are reduced considerably. In this
 manner, the high-frequency focusing errors are substantially exclusively
 corrected by means of relatively small displacements of the auxiliary lens
 55 in a direction parallel to the optical axis 39, which, in practice,
 proved possible because the high-frequency focusing errors only have a
 relatively small amplitude. In addition, it has been found that such small
 displacements of only the auxiliary lens 55 have almost no influence on
 the spherical aberration of the radiation beam 45 in the protective layer
 13 of the information carrier 9, so that the displacements of the
 auxiliary lens 55 almost do not have to be compensated by displacements of
 the main lens 53 relative to the auxiliary lens 55 by means of the second
 actuator 63.
 As described hereinabove, the mounting elements 65, 67 of the lens system
 37 each includes three bendable bridges 73, which extend in a plane
 transverse to the optical axis 39 and which are mutually placed at regular
 intervals. As shown in FIG. 4, the bendable bridges 73 each includes a
 uniformly bendable spoke which extends substantially in a tangential
 direction relative to the optical axis 39 of the lens system 37. As a
 result, a simple and robust construction of the mounting elements 65, 67
 is obtained. FIG. 5 shows an alternative mounting element 65', 67' which
 may be used in the lens system 37 instead of the mounting element 65, 67
 shown in FIG. 4. The alternative mounting element 65', 67' includes, just
 like the mounting element 65, 67, a first predominantly ring-shaped
 portion 69' which is secured to the housing 57 of the lens system 37, and
 a second predominantly ring-shaped portion 71', which is secured to the
 holder 59 of the main lens 53. The ringshaped portions 69', 71' of the
 alternative mounting element 65', 67' shown in FIG. 5 are interconnected
 by three bendable bridges 73', which extend in a plane transverse to the
 optical axis 39 and are mutually placed at regular intervals, each of the
 bendable bridges including a relatively rigid strip 87 which extends
 predominantly in a tangential direction relative to the optical axis 39
 and is connected, via two flexible joints 89, 91, to the two ring-shaped
 portions 69', 71'. By using said strips 87 and said flexible joints 89,
 91, the mounting elements 65', 67' can be manufactured in a simple manner
 by providing a relatively small number of incisions in a sheet material.
 The above-described mounting elements 65, 67, 65', 67' each include three
 bendable bridges 73, 73'. It is noted that, in accordance with the
 invention, the mounting elements 65, 67, 65', 67' may alternatively
 include a different number of bendable bridges 73, 73'. In accordance with
 the invention, however, a first one of the mounting elements 65, 67, 65',
 67' should include at least three bendable bridges 73, 73' which extend in
 a plane transverse to the optical axis 39 and are arranged at regular
 distances from each other, and a second one of the mounting elements 65,
 67, 65', 67' should include at least two bendable bridges 73, 73' which
 extend in a plane transverse to the optical axis 39. If the first mounting
 element 65, 67, 65', 67' is provided, as described above, with three
 bendable bridges 73, 73', and the second mounting element 65, 67, 65', 67'
 is provided, as described above, with two bendable bridges 73, 73', a
 so-called statically determined, i.e. substantially stress-free,
 suspension of the main lens 53 in the housing 57 is obtained, in which
 case the main lens 53 can only be displaced parallel to the optical axis
 39. This is based on the recognition that each individual bendable bridge
 73, 73' serves mainly as a mechanical rod by means of which substantially
 only forces directed parallel to a longitudinal direction of the bendable
 bridge 73, 73' are transmitted. If the mounting elements 65, 67, 65', 67'
 include a larger number of bendable bridges 73, 73', a suspension of the
 main lens 53 in the housing 57 is achieved which is not statically
 determined, but the main lens 53 can be displaced parallel to the optical
 axis 39 just the same.
 As is further shown in FIG. 3, the housing 57 of the lens system 37
 includes a first part 95, a second part 97 and a third part 99, the
 auxiliary lens 55 being secured in a fixed position to the first part 95,
 the mounting element 65 being secured to the second part 97, and the
 mounting 67 being secured to the third part 99. The third part 99 of the
 housing 57 is formed by the closing yoke 79 of the second actuator 63. As
 schematically shown in FIGS. 6a and 6b, in the course of the manufacture
 of the lens system 37, the three parts 95, 97, 99 of the housing 57 are
 mutually manipulated by means of a manipulator 101 in such a manner that
 the main lens 53 and the auxiliary lens 55 are aligned relative to each
 other into a position in which the optical axes of the main lens 53 and
 the auxiliary lens 55 coincide and hence constitute the optical axis 39 of
 the lens system 37. To this end, the first art 95 of the housing 57 is
 coupled to a reference 103 of the manipulator 101, while the second part
 97 of the housing 57 is coupled to a first effector 105 of the manipulator
 101 and the third part 99 of the housing 57 is coupled to a second
 effector 107 of the manipulator 101. It is noted that in the FIGS. 6a and
 6b, the manipulator 101 is not shown in further detail for the sake of
 simplicity. To align the main lens 53 and the auxiliary lens 55, the main
 lens 53 is displaced over a necessary distance relative to the auxiliary
 lens 55 in a direction transverse to the optical axis 39 by means of the
 manipulator 101, so that the main lens 53 and the auxiliary lens 55 are
 centered relative to each other, and the main lens 53 is tilted, relative
 to the auxiliary lens 55, through a necessary angle, about a tilt axis
 extending transversely to the optical axis 39 by means of the manipulator
 101, so that the optical axes of the main lens 53 and the auxiliary lens
 55 are brought into mutually parallel positions. To displace the main lens
 53 relative to the auxiliary lens 55 in a direction transverse to the
 optical axis 39, the effectors 105 and 107 of the manipulator 101 are
 displaced over equal distances in an equal direction transverse to the
 optical axis 39, as is shown in FIG. 6a. As a result, the second part 97
 of the housing 57 slides over the first part 95 of the housing 57. To tilt
 the main lens 53 relative to the auxiliary lens 55 about a tilt axis
 directed transversely to the optical axis 39, the effectors 105 and 107 of
 the manipulator 101 are displaced over equal distances, in opposite
 directions transverse to the optical axis 39 of the main lens 53, as is
 shown in FIG. 6b. As a result, the second part 97 of the housing 57 slides
 over the first part 95 of the housing 57, and the third part 99 of the
 housing 57 slides over the second part 97 of the housing 57. After the
 main lens 53 and the auxiliary lens 55 have been mutually aligned in this
 manner, the three parts 95, 97, 99 of the housing 57 are fixed relative to
 each other. Since the effectors 105, 107 of the manipulator 101 only carry
 out displacements in a direction transverse to the optical axis 39 during
 the aligning operation, the manipulator 101 may be of a simple type.
 By means of the above-described optical player in accordance with the
 invention, during scanning the information track of the information
 carrier 9, information present on the information track can be read or
 information can be written on the information track. It is noted that the
 invention also relates to optical players which can only be used to read
 information present on an information track of an information carrier.
 Finally, it is noted that in accordance with the invention, instead of the
 above-described mounting unit 61, the main lens 53 of the lens system 37
 may include a different type of elastical deformable mounting unit by
 means of which the main lens 53, viewed parallel to the optical axis 39,
 suspended in the housing 57. An example of such a different type of
 mounting unit is a leaf spring.
 The invention has been disclosed with reference to specific preferred
 embodiments, to enable those skilled in the art to make and use the
 invention, and to describe the best mode contemplated for carrying out the
 invention. Those skilled in the art may modify or add to these embodiments
 or provide other embodiments without departing from the spirit of the
 invention. The scope of the invention is not limited to the embodiments,
 but lies in each and every novel feature or combination of features
 described above and in every novel combination of these features. Thus,
 the scope of the invention is only limited by the following claims: