CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority from U.S. Provisional patent applications No. 62/671,086 filed May 14, 2018 and 62/755,826 filed November 5, 2018, both of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The presently disclosed subject matter is generally related to the field of digital cameras.

BACKGROUND

Dual-aperture zoom cameras (also referred to as dual-cameras), in which one camera (also referred to as“sub-camera”) has a Wide FOV (“Wide sub-camera”) and the other has a narrow FOV (“Tele sub-camera”), are known.

International patent publication WO 2016/024192, which is incorporated herein by reference in its entirety, discloses a "folded camera module" (also referred to simply as "folded camera") that reduces the height of a compact camera. In the folded camera, an optical path folding element (referred to hereinafter as "OPFE") e.g. a prism or a mirror (otherwise referred to herein collectively as“reflecting element”) is added in order to tilt the light propagation direction from perpendicular to the smart-phone back surface to parallel to the smart-phone back surface. If the folded camera is part of a dual-aperture camera, this provides a folded optical path through one lens assembly (e.g. a Tele lens). Such a camera is referred to herein as "folded-lens dual-aperture camera". In general, the folded camera may be included in a multi-aperture camera, for example together with two "non-folded" (upright) camera modules in a triple- aperture camera.

SUMMARY

A small height of a folded camera is important to allow a host device (e.g. a smartphone, tablets, laptops or smart TV) that includes it to be as thin as possible. The height of the camera is often limited by the industrial design. In contrast, increasing the optical aperture of the lens results in an increase in the amount of light arriving at the image sensor and improves the optical properties of the camera.

Therefore, there is a need for, and it would be advantageous to have a folded camera in which the height of the lens optical aperture is maximal for a given camera height and/or for a lens module height.

In exemplary embodiments, there are provided high optical performance lenses (or “lens assemblies") with a large front clear aperture (CA), a large first surface CA and relatively small clear apertures for all other lens elements. The lens elements are listed in order from an object side (first lens element Li) to an image side (last lens element Li). In each embodiment, the last lens element clear aperture is smaller than the diagonal length of an image sensor (also referred to herein as“sensor diagonal length” or“SDL”) included with the lens in a digital camera. In the following Tables, all dimensions are given in millimeters. All terms and acronyms have their ordinary meaning as known in the art.

In some embodiments, there are provided folded lens assemblies for a folded camera, comprising: a plurality of lens elements that include, in order for an object side to an image side, a first lens element Li with a clear aperture CA(Si) and a second lens element L ₂ with a clear aperture CA(S ₃ ), wherein CA(S I)/CA(S ₃ ) > 1.2 and wherein the lens assembly has a ratio between an image sensor diagonal length SDL and a clear aperture of a last lens element surface CA(S _2N ), SDL/CA(S _2n ) > 1.5.

In some embodiments, the first lens element has positive refractive power and the second lens element has negative refractive power, and the plurality of lens elements further includes a third lens element with positive refractive power and a fourth lens element with negative refractive power.

In some embodiments, the first lens element has positive refractive power and the second lens element has negative refractive power, and the plurality of lens elements further includes a third lens element with positive refractive power and a fourth lens element with positive refractive power.

In some embodiments, the first lens element has positive refractive power and the second lens element has negative refractive power, and the plurality of lens elements further includes a third lens element with negative refractive power and a fourth lens element with positive refractive power.

In some embodiments, the plurality of lens elements further includes a fifth lens element with negative refractive power. In some embodiments, the lens assembly has a total track length (TTL) and a back focal length (BFL) with a ratio BFL/TTL > 0.35.

In some embodiments, an optical window is positioned in a path defining the BFL and the TTL.

In some embodiments, there are provided folded lens assemblies for a folded camera, comprising: a plurality N of lens elements that include, in order for an object side to an image side, a first lens element Li with a clear aperture CA(Si), wherein all clear apertures of all other lens elements L ₂ to L _N of the plurality N of lens elements are no larger than CA(Si), wherein the folded camera includes an image sensor having a sensor diagonal length SDL and wherein CA(Si) < SDL< L5 x CA(Si).

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting examples of embodiments disclosed herein are described below with reference to figures attached hereto that are listed following this paragraph. The drawings and descriptions are meant to illuminate and clarify embodiments disclosed herein, and should not be considered limiting in any way. Like elements in different drawings may be indicated by like numerals. Elements in the drawings are not necessarily drawn to scale. In the drawings:

FIG. 1A is a general isometric view of an example of a known folded camera;

FIG. IB is a side view of the camera of FIG. 1A;

FIG. 1C is a general isometric view of an example of a known camera comprising a folded Tele sub-camera and a Wide sub-camera;

FIG. ID is a side view of the camera of FIG. 1C;

FIG. 2A is a schematic view of one embodiment of lens elements with light rays according to some examples of the presently disclosed subject matter;

FIG. 2B is another schematic view of the lens elements of FIG. 2A;

FIG. 3A is a schematic view of impact points of optical rays impinging a convex surface of a lens element, and a schematic view of the orthogonal projection of the impact points on a plane P, according to some examples of the presently disclosed subject matter;

FIG. 3B is a schematic view of impact points of optical rays impinging a concave surface of a lens element, and a schematic view of the orthogonal projection of the impact points on a plane P, according to some examples of the presently disclosed subject matter;

FIG. 4 is a schematic representation of the orthogonal projection of the impact points on a plane P, and of a clear height value (“CH”), according to some examples of the presently disclosed subject matter;

FIG. 5 is a schematic representation of the orthogonal projection of the impact points on a plane P, and of a clear aperture value (“CA”), according to some examples of the presently disclosed subject matter;

FIG. 6 is a schematic view of another embodiment of lens elements with light rays according to some examples of the presently disclosed subject matter;

FIG. 7 is a schematic view of yet another embodiment of lens elements with light rays according to some examples of the presently disclosed subject matter;

FIG. 8 is a schematic view of yet another embodiment of lens elements with light rays according to some examples of the presently disclosed subject matter;

FIG. 9 is a schematic view of yet another embodiment of lens elements with light rays according to some examples of the presently disclosed subject matter;

FIG. 10 is a schematic view of yet another embodiment of lens elements with light rays according to some examples of the presently disclosed subject matter;

FIG. 11 is a schematic view of yet another embodiment of lens elements with light rays according to some examples of the presently disclosed subject matter;

FIG. 12 is a schematic view of yet another embodiment of lens elements with light rays according to some examples of the presently disclosed subject matter;

FIG. 13 is a schematic representation of a side view of an optical lens module for holding the lens elements, according to some examples of the presently disclosed subject matter;

FIG. 14A is a schematic view of another embodiment of lens elements showing light rays, according to another example of the presently disclosed subject matter;

FIG. 14B is another schematic view of the lens elements of FIG. 14A.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding. However, it will be understood by those skilled in the art that the presently disclosed subject matter may be practiced without these specific details. In other instances, well-known methods have not been described in detail so as not to obscure the presently disclosed subject matter.

It is appreciated that certain features of the presently disclosed subject matter, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the presently disclosed subject matter, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The term "processing unit" as disclosed herein should be broadly construed to include any kind of electronic device with data processing circuitry, which includes for example a computer processing device operatively connected to a computer memory (e.g. digital signal processor (DSP), a microcontroller, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), etc.) capable of executing various data processing operations.

Furthermore, for the sake of clarity the term "substantially" is used herein to imply the possibility of variations in values within an acceptable range. According to one example, the term "substantially" used herein should be interpreted to imply possible variation of up to 10% over or under any specified value. According to another example, the term "substantially" used herein should be interpreted to imply possible variation of up to 5% over or under any specified value. According to a further example, the term "substantially" used herein should be interpreted to imply possible variation of up to 2.5% over or under any specified value.

FIGS. 1A and IB illustrate a digital folded camera 100, which may operate for example as a Tele camera. Digital camera 100 comprises a first reflecting element (e.g. mirror or prism, and also referred to sometimes as“optical path folding element” (OPFE)) 101, a plurality of lens elements (not visible in this representation, but visible e.g. in FIGS. 2A and 2B) and an image sensor 104. The lens elements (and also barrel, the optical lens module) may have axial symmetric along a first optical axis 103. At least some of the lens elements can be held by a structure called a“barrel” 102. An optical lens module comprises the lens elements and the barrel. The barrel can have a longitudinal symmetry along optical axis 103. In FIGS. 1A to ID, the cross-section of this barrel is circular. This is, however, not mandatory and other shapes can be used.

The path of the optical rays from an object (not shown) to image sensor 104 defines an optical path (see optical paths 105 and 106, which represent portions of the optical path).

OPFE 101 may be a prism or a mirror. As shown in FIG. 1A, OPFE 101 can be a mirror inclined with respect to optical axis 103. In other cases (not shown, see for example PCT/IB2017/052383), OPFE 101 can be a prism with a back surface inclined with respect to optical axis 103. OPFE folds the optical path from a first optical path 105 to a second optical path 106. Optical path 106 is substantially parallel to the optical axis 103. The optical path is thus referred to as "folded optical path" (indicated by optical paths 105 and 106) and camera 100 is referred to as "folded camera".

In particular, in some examples, OPFE 101 can be inclined at substantially 45° with respect to optical axis 103. In FIG. 1A, OPFE 101 is also inclined at substantially 45° with respect to optical path 105.

In some known examples, image sensor 104 lies in a X-Y plane substantially perpendicular to optical axis 103. This is however not limiting and the image sensor 104 can have a different orientation. For example, and as described in WO 2016/024192, image sensor 104 can be in the XZ plane. In this case, an additional OPFE can be used to reflect the optical rays towards image sensor 104.

According to some examples, image sensor 104 has a rectangular shape. According to some examples, image sensor 104 has a circular shape. These examples are however not limiting.

In various examples camera 100 may be mounted on a substrate 109, e.g. a printed circuit board (PCB), as known in the art.

Two sub-cameras, for example a Wide sub-camera 130 and a Tele sub-camera 100 may be included in a digital camera 170 (also referred to as dual-camera or dual-aperture camera). A possible configuration is described with reference to FIGS. 1C and ID. In this example, Tele sub-camera 100 is according to the camera described with reference to FIGS. 1A and IB. The components of Tele sub-camera 100 thus have the same reference numbers as in FIGS. 1A and IB, and are not described again.

Wide sub-camera 130 can include an aperture 132 (indicating object side of the camera) and an optical lens module 133 (or "Wide lens module") with a symmetry (and optical) axis 134 in the Y direction, as well as a Wide image sensor 135. The Wide lens module is configured to provide a Wide image. The Wide sub-camera has a Wide field of view (FOVw) and the Tele sub-camera has a Tele field of view (FOV _T ) narrower than FOVw. Notably, in some examples, a plurality of Wide sub-cameras and/or a plurality of Tele sub-cameras can be incorporated and operative in a single digital camera.

According to one example, the Wide image sensor 135 lies in the X-Z plane, while image sensor 104 (which is in this example is a Tele image sensor) lies in a X-Y plane substantially perpendicular to optical axis 103.

In the examples of FIGS. 1A to ID, camera 100 can further include (or be otherwise operatively connected to) a processing device comprising one or more suitably configured processors (not shown) for performing various processing operations, for example processing the Tele image and the Wide image into a fused output image. The processing unit may include hardware (HW) and software (SW) specifically dedicated for operating with the digital camera. Alternatively, a processor of an electronic device (e.g. its native CPU) in which the camera is installed can be adapted for executing various processing operations related to the digital camera (including, but not limited to, processing the Tele image and the Wide image into an output image).

Attention is now drawn to FIGS. 2A and 2B, which show schematic view of a lens module 200 having lens elements shown with optical rays according to some examples of the presently disclosed subject matter. Lens module 200 is shown without a lens barrel. FIG. 2A shows optical ray tracing of lens module 200 while FIG. 2B shows only the lens elements for more clarity. In addition, both figures show an image sensor 202 and an optical element 205.

Lens module 200 includes a plurality of N lens elements Li (wherein“i” is an integer between 1 and N). Li is the lens element closest to the object side and LN is the lens element closest to the image side, i.e. the side where the image sensor is located. This order holds for all lenses and lens elements disclosed herein. Lens elements Li can be used e.g. as lens elements of camera 100 represented in FIGS. 1A and IB or as lens elements of the Tele sub-camera 100 of FIGS. 1C and ID. As shown, the N lens elements are axial symmetric along optical axis 103.

In the examples of FIGS. 2A and 2B, N is equal to four. In the examples in FIGS. 6-12, N is equal to 5. This is however not limiting and a different number of lens elements can be used. For example, N can be equal to 3, 6 or 7.

In the examples of FIGS. 2A and 2B, some of the surfaces of the lens elements are represented as convex, and some are represented as concave. The representation of FIGS. 2A and 2B is however not limiting and a different combination of convex and/or concave surfaces can be used, depending on various factors such as the application, the desired optical power, etc.

Optical rays (after their reflection by a reflecting element, such as OPFE 101) pass through lens elements Li and form an image on an image sensor 202. In the examples of FIGS. 2A and 2B, the optical rays pass through an optical element 205 (which comprises a front surface 205a and a rear surface 205b _, and can be e.g. a cut-off filter) also referred to as“optical window” or simply“window” before impinging on image sensor 202. This is however not limiting, and in some examples, optical element 205 is not present. Optical element 205 may be for example infra-red (IR) filter, and/or a glass image sensor dust cover.

Each lens element Li comprises a respective front surface S _2i-i (the index“2i- 1” being the number of the front surface) and a respective rear surface S _2i (the index“2i” being the number of the rear surface), where“i” is an integer between 1 and N. This numbering convention is used throughout the description. Alternatively, as done throughout this description, lens surfaces are marked as“S _k ”, with k running from 1 to 2N. The front surface and the rear surface can be in some cases aspherical. This is however not limiting.

As used herein the term "front surface" of each lens element refers to the surface of a lens element located closer to the entrance of the camera (camera object side) and the term "rear surface" refers to the surface of a lens element located closer to the image sensor (camera image side).

As explained below, a clear height value CH(S _k ) can be defined for each surface S _k for 1 < k < 2N), and a clear aperture value CA(S _k ) can be defined for each surface S _k for 1 < k < 2N). CA(S _k ) and CH(S _k ) define optical properties of each surface S _k of each lens element.

As shown in FIGS. 3A, 3B and 4, each optical ray that passes through a surface S _k (for 1 < k < 2N) impinges this surface on an impact point IP. Optical rays enter lens module 200 from surface Si, and pass through surfaces S ₂ to S ₂ N consecutively. Some optical rays can impinge on any surface S _k but cannot /will not reach image sensor 202. For a given surface S _k , only optical rays that can form an image on image sensor 202 are considered forming a plurality of impact points IP are obtained. CH(S _k ) is defined as the distance between two closest possible parallel lines (see lines 400 and 401 in FIG. 4 located on a plane P orthogonal to the optical axis of the lens elements (in the representation of FIGS. 3A and 3B, plane P is parallel to plane X-Y and is orthogonal to optical axis 103), such that the orthogonal projection IP _orth of all impact points IP on plane P is located between the two parallel lines. CH(S _k ) can thus be defined for each surface S _k (front and rear surfaces, with 1 < k < 2N).

The definition of CH(S _k ) does not depend on the object currently imaged, since it refers to the optical rays that“can” form an image on the image sensor. Thus, even if the currently imaged object is located in a black background that does not produce light, the definition does not refer to this black background since it refers to any optical rays that“can” reach the image sensor to form an image (for example optical rays emitted by a background that would emit light, contrary to a black background).

For example, FIG. 3A illustrates the orthogonal projections IP _{orth, i} , IP _orth,i of two impact points IPi and IP ₂ on plane P which is orthogonal to optical axis 103 _. By way of example, in the representation of FIG. 3A, surface S _k is convex.

FIG. 3B illustrates the orthogonal projections IP _{orth, 3} , IP _{orth, 4} of two impact points IP ₃ and IP ₄ on plane P _. By way of example, in the representation of FIG. 3B, surface S _k is concave.

In FIG. 4, the orthogonal projection IP _orth of all impact points IP of a surface S _k on plane P is located between parallel lines 400 and 401. CH(S _k ) is thus the distance between lines 400 and 401.

Attention is drawn to FIG. 5. According to the presently disclosed subject matter, a clear aperture CA(S _k ) is defined for each given surface S _k (for 1 < k < 2N), as the diameter of a circle, wherein the circle is the smallest possible circle located in a plane P orthogonal to the optical axis 103 and encircling all orthogonal projections IP _o r _th of all impact points on plane P. As mentioned above with respect to CH(S _k ), it is noted that the definition of CA(S _k ) also does not depend on the object which is currently imaged.

As shown in FIG. 5, the circumscribed orthogonal projection IP _orth of all impact points IP on plane P is circle 500. The diameter of this circle 500 defines CA(S _k ).

Detailed optical data and surface data are given in tables below for ten lens (or lens assembly) examples (embodiments) numbered as Exl, Ex2,...Ex 10. The ten lens assembly embodiments Exl to ExlO are also shown in, respectively, FIGS. 2, 6, 7, 8, 9, 10, 11, 12, 13 andl4.

Characteristics description tables

Tables 1, 4, 7, 10, 13, 16, 19, 22, 25 and 28 provide respectively a summary of lens properties for each of examples 1-10. For each lens, the following parameters are described:

Effective focal length (EFL), in millimeters (mm).

Total track length (TTL), in mm, defined as the distance from the first surface Si of the first lens element to the image sensor. In some embodiments, an optical window is positioned in, and included in the TTL.

f number f/#, (unitless number).

Image sensor diagonal length (SDL), in mm.

Back focal length (BFL), in mm, which is the distance from the last surface of the last lens element S _2N to the image sensor. In some embodiments, an optical window is positioned in, and included in the BFL.

Ratio between the TTL and the EFL, TTL/EFL.

Ratio between the BFL and the EFL, BFL/EFL.

Ratio between the clear aperture (CA) of the first surface Si of the first lens element and the clear aperture of the first surface S ₃ of the second lens element, CA(S I)/CA(S ₃ ). Focal length of each lens element, T. Surface tables

Tables 2, 5, 8, 11, 14, 17, 20, 23, 26 and 29 provide respectively a description of the surfaces of each element for each of embodiments Exl, Ex2,...Ex 10. For each lens element and each surface, the following parameters are described:

Surface type (see below).

The lens element number L and surface number.

The surface radius in mm, infinity means flat surface.

The thickness between surface i to surface i+l .

The surface refraction index Nd.

The surface abbe number Vd.

The surface half diameter D/2.

Aspheric Surface Coefficients tables:

Tables 3, 6, 9, 12, 15, 18, 21, 24, 27 and 30 provide respectively a further description of aspheric surfaces of each lens element in each of embodiments Exl, Ex2,...Ex 10.

Surface

a) Q type 1 surface sag formula:

u = , x = u ²

Dnax

Q _Q ^con (x) = 1 Ql ^on = -(5 - 6x) Q ₂ ^c ° ⁿ = 15 - 14x(3 - 2x)

Ql° ⁿ = -{35 - 12x[14 - x(21 - 10x)]}

Q ^con ₌ 70 _ 3 {i68 - 5x[84 - llx(8 - 3x)]}

Qcon ₌ _ [ ₁₂₆ _ X(1260 - llx{420 - x[720 - 13x(45 - 14x)]})] where {z, r} are the standard cylindrical polar coordinates, c is the paraxial curvature of the surface, k is the conic parameter, r _max is one half of the surfacs clear aperture, and A _n are the polynomial coefficients shown in lens data tables. b) Even aspheric surfaces formula:

The equation of the surface profiles of each surface S _k (for k between 1 and 2N) is expressed by:

?

CT

z = - +A ₁ r ⁴ + A ₂ r ⁶ +A ₃ r ⁸ +A ₄ r ¹⁰ +A ₅ r ¹² + A ₆ r ¹⁴ + A ₇ r ¹⁶

1 + Vl - (1 + k)c ² r ²

where "z" is the position of the profile of the surface S _k measured along optical axis 103 (coinciding with the Z axis, wherein z = 0 corresponds to the intersection of the profile of the surface S _k with the Z axis), "r" is the distance from optical axis 103 (measured along an axis which is perpendicular to optical axis 103),“K” is the conic coefficient, c = l/R where R is the radius of curvature, and A _n (n from 1 to 7) are coefficients given in Tables 2 and 4 for each surface S _k. The maximum value of r,“max r”, is equal to D/2.

c) Flat surface;

d) Stop.

The values provided for these examples are purely illustrative and according to other examples, other values can be used.

In the tables below, the units of the radius of curvature (“R”), the lens element thickness (“T”) and the clear aperture are expressed in millimeters.

Line“0” of Tables 1, 3 and 5 and 7 describes parameters associated to the object (not visible in the figures); the object is being placed at lkm from the system, considered to be an infinite distance.

Lines“1” to“8” of Tables 1 to 4 describe respectively parameters associated to surfaces Si to S ₈ . Lines“1” to“10” of Tables 5 to 8 describe respectively parameters associated with surfaces Si to Sio.

Lines“9”,“10” and“11” of Tables 1 and 3, and lines“11”,“12” and“13” in Tables 5 and 7 describe respectively parameters associated with surfaces 205a, 205b of optical element 205 and of a surface 202a of the image sensor 202.

In lines“i” of Tables 1, 3 and 5 (with i between 1 and 10 in tables 1 and 3 and i between 1 and 12 in Table 5), the thickness corresponds to the distance between surface Si and surface Si+i , measured along the optical axis 103 (which coincides with the Z axis).

In line“11” of Tables 1, 3 (line“13” in Tables 5 and 7), the thickness is equal to zero, since this corresponds to the last surface 202a. Example 1:

Table 1

Table 2

Tab e 3 Example 2

Table 4

Table 5

Table 6 Example 3

Table 7

Table 8

Tab e 9 Example 4

Table 10

Table 11

Tab e 12 Example 5

Table 13

Table 14

Tab e 15 Example 6

Table 16

Table 17

Table 18 Example 7

Table 19

Table 20

Tab e 21 Example 8

Table 22

Table 23

Table 24 Example 9

Table 25

Table 26

Tab e 27 Example 10

Table 28

Table 29

Tab e 30 Sign of refractive elements:

Table 31

Table 32 The following list and Table 33 summarize the design characteristics and parameters as they appear in the examples listed above. These characteristics helps to achieve the goal of a compact folded lens with large lens assembly aperture:

“AA”: AAi º BFL/TTL > 0.35, AA _{2 º} BFL/TTL > 0.4, AA _{3 º} BFL/TTL > 0.5;

“BB”: BBI º CA(SI)/CA(S ₃ ) > 1.2, BB ₂ º CA(SI)/CA(S ) > 1.3, BB _º CA(Si)/CA(S )

> 1.4;

“CC”: CCi º T(AS to S )/TTL > 0.1, CC _{2 º} T(AS to S )/TTL > 0.135, CC _º T(AS to S ₃ )/TTL > 0.15;

“DD”: At least two gaps that comply with DDi º STD < 0.020, DD _{2 º} STD < 0.015, DD _º STD < 0.010;

“EE”: At least 3 gaps that comply with EEi º STD < 0.035, EE _{2 º} STD <0.025, EE ₃ º STD <0.015;

“FF”: At least 4 gaps that comply with FFi º STD <0.050, FF _{2 º} STD < 0.035, FF _{3 º} STD <0.025;

“GG”: GGi º SDL/C A(S _2N ) > 1.5, GG _{2 º} SDL/C A(S _2N ) > 1.55, GG _º SDL/C A(S _2N )

> 1.6;

“HH”: a power sign sequence;

“P”: At least 1 gap that complies with Hi º STD<0.0l and OA_Gap/TTL<l/80, II ₂ º STDO.015 and OA_Gap/TTL<l/65;

“JJ”: JJ i : Abbe number sequence of lens elements Li, L ₂ and L ₃ can be respectively larger than 50, smaller than 30 and larger than 50;

JJ ₂ : Abbe number sequence of lens elements Li, L ₂ and L ₃ can be respectively larger than 50, smaller than 30 and smaller than 30;

“KK”: KKi º |f ₂ /fi| > 0.4 and Abbe number sequence of lens elements Li, L ₂ and L ₃ can be respectively larger than 50, smaller than 30 and smaller than 30; , KK _{2 º} |f ₂ /fi|<0.5 and Abbe number sequence of lens elements Li, L ₂ and L ₃ can be respectively larger than 50, smaller than 30 and larger than 50; and

“LL”: LLi º fi/EFL<0.55, LL _{2 º} fi/EFL <0.45;

“MM”:MMi º |f ₂ /fi|<0.9, MM _{2 º} |f ₂ /fi|<0.5; and

“NN”: NNi º TTL/EFL<0.99, NN _{2 º} TTL/EFL<0.97, NN _{3 º} TTL/EFL<0.95.

“OO”: At least two gaps that comply with OO i º STD > 0.020, OO _{2 º} STD > 0.03, OO _{3 º} STD > 0.040; “PP”: At least 3 gaps that comply with PP i = STD > 0.015, PP ₂ = STD >0.02, PP 3 = STD >0.03;

“QQ”: At least 4 gaps that comply with QQ 1 º STD >0.015, QQ 2 = STD > 0.02, QQ 3 º STD >0.03;

“RR”: At least 3 OA_Gaps that comply with RR 1 º TTL/Min Gap >50, RR 2 = TTL/Min_Gap >60, RR _{3 º} TTL/Min_Gap >100.

Table 33

Unless otherwise stated, the use of the expression“and/or” between the last two members of a list of options for selection indicates that a selection of one or more of the listed options is appropriate and may be made.

It should be understood that where the claims or specification refer to "a" or "an" element, such reference is not to be construed as there being only one of that element.

All patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present disclosure.