Folded camera lens designs

Folded lens modules and assemblies characterized by low height and large entrance pupil (clear aperture), designed for folded cameras in consumer electronics and specifically in mobile phones. In some embodiments, a folded lens assembly comprises a plurality of lens elements that include, in order for an object side to an image side, a first lens element L1 with a clear aperture CA(S1) and a second lens element L2 with a clear aperture CA(S3), wherein CA(S1)/CA(S3)>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(S2N), SDL/CA(S2N)>1.5.

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 L1) 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 L1with a clear aperture CA(S1) and a second lens element L2with a clear aperture CA(S3), wherein CA(S1)/CA(S3)>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(S2N), SDL/CA(S2N)>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 L1with a clear aperture CA(S1), wherein all clear apertures of all other lens elements L2to LNof the plurality N of lens elements are no larger than CA(S1), wherein the folded camera includes an image sensor having a sensor diagonal length SDL and wherein CA(S1)<SDL<1.5×CA(S1).

DETAILED DESCRIPTION

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 and1Billustrate a digital folded camera100, which may operate for example as a Tele camera. Digital camera100comprises 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. inFIGS.2A and2B) and an image sensor104. The lens elements (and also barrel, the optical lens module) may have axial symmetric along a first optical axis103. 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 axis103. InFIGS.1A to1D, 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 sensor104defines an optical path (see optical paths105and106, which represent portions of the optical path).

OPFE101may be a prism or a mirror. As shown inFIG.1A, OPFE101can be a mirror inclined with respect to optical axis103. In other cases (not shown, see for example PCT/IB2017/052383), OPFE101can be a prism with a back surface inclined with respect to optical axis103. OPFE folds the optical path from a first optical path105to a second optical path106. Optical path106is substantially parallel to the optical axis103. The optical path is thus referred to as “folded optical path” (indicated by optical paths105and106) and camera100is referred to as “folded camera”.

In particular, in some examples, OPFE101can be inclined at substantially 45° with respect to optical axis103. InFIG.1A, OPFE101is also inclined at substantially 45° with respect to optical path105.

In some known examples, image sensor104lies in a X-Y plane substantially perpendicular to optical axis103. This is however not limiting and the image sensor104can have a different orientation. For example, and as described in WO 2016/024192, image sensor104can be in the XZ plane. In this case, an additional OPFE can be used to reflect the optical rays towards image sensor104.

According to some examples, image sensor104has a rectangular shape. According to some examples, image sensor104has a circular shape. These examples are however not limiting.

In various examples camera100may be mounted on a substrate109, e.g. a printed circuit board (PCB), as known in the art.

Two sub-cameras, for example a Wide sub-camera130and a Tele sub-camera100may be included in a digital camera170(also referred to as dual-camera or dual-aperture camera). A possible configuration is described with reference toFIGS.1C and1D. In this example, Tele sub-camera100is according to the camera described with reference toFIGS.1A and1B. The components of Tele sub-camera100thus have the same reference numbers as inFIGS.1A and1B, and are not described again.

Wide sub-camera130can include an aperture132(indicating object side of the camera) and an optical lens module133(or “Wide lens module”) with a symmetry (and optical) axis134in the Y direction, as well as a Wide image sensor135. 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 (FOVT) 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 sensor135lies in the X-Z plane, while image sensor104(which is in this example is a Tele image sensor) lies in a X-Y plane substantially perpendicular to optical axis103.

In the examples ofFIGS.1A to1D, camera100can 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 toFIGS.2A and2B, which show schematic view of a lens module200having lens elements shown with optical rays according to some examples of the presently disclosed subject matter. Lens module200is shown without a lens barrel.FIG.2Ashows optical ray tracing of lens module200whileFIG.2Bshows only the lens elements for more clarity. In addition, both figures show an image sensor202and an optical element205.

Lens module200includes a plurality of N lens elements Li(wherein “i” is an integer between 1 and N). L1is the lens element closest to the object side and LNis 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 Lican be used e.g. as lens elements of camera100represented inFIGS.1A and1Bor as lens elements of the Tele sub-camera100ofFIGS.1C and1D. As shown, the N lens elements are axial symmetric along optical axis103.

In the examples ofFIGS.2A and2B, N is equal to four. In the examples inFIGS.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 ofFIGS.2A and2B, some of the surfaces of the lens elements are represented as convex, and some are represented as concave. The representation ofFIGS.2A and2Bis 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 OPFE101) pass through lens elements Liand form an image on an image sensor202. In the examples ofFIGS.2A and2B, the optical rays pass through an optical element205(which comprises a front surface205aand a rear surface205b, and can be e.g. a cut-off filter) also referred to as “optical window” or simply “window” before impinging on image sensor202. This is however not limiting, and in some examples, optical element205is not present. Optical element205may be for example infra-red (IR) filter, and/or a glass image sensor dust cover.

Each lens element Licomprises a respective front surface S2i−1(the index “2i−1” being the number of the front surface) and a respective rear surface S2i(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 “Sk”, 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(Sk) can be defined for each surface Skfor 1≤k≤2N), and a clear aperture value CA(Sk) can be defined for each surface Skfor 1≤k≤2N). CA(Sk) and CH(Sk) define optical properties of each surface Skof each lens element.

As shown inFIGS.3A,3B and4, each optical ray that passes through a surface Sk(for 1≤k≤2N) impinges this surface on an impact point IP. Optical rays enter lens module200from surface S1, and pass through surfaces S2to S2Nconsecutively. Some optical rays can impinge on any surface Skbut cannot/will not reach image sensor202. For a given surface Sk, only optical rays that can form an image on image sensor202are considered forming a plurality of impact points IP are obtained. CH(Sk) is defined as the distance between two closest possible parallel lines (see lines400and401inFIG.4located on a plane P orthogonal to the optical axis of the lens elements (in the representation ofFIGS.3A and3B, plane P is parallel to plane X-Y and is orthogonal to optical axis103), such that the orthogonal projection IPorthof all impact points IP on plane P is located between the two parallel lines. CH(Sk) can thus be defined for each surface Sk(front and rear surfaces, with 1≤k≤2N).

The definition of CH(Sk) 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.3Aillustrates the orthogonal projections IPorth,1, IPorth,2of two impact points IP1and IP2on plane P which is orthogonal to optical axis103. By way of example, in the representation ofFIG.3A, surface Skis convex.

FIG.3Billustrates the orthogonal projections IPorth,3, IPorth,4of two impact points IP3and IP4on plane P. By way of example, in the representation ofFIG.3B, surface Skis concave.

InFIG.4, the orthogonal projection IPorthof all impact points IP of a surface Skon plane P is located between parallel lines400and401. CH(Sk) is thus the distance between lines400and401.

Attention is drawn toFIG.5. According to the presently disclosed subject matter, a clear aperture CA(Sk) is defined for each given surface Sk(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 axis103and encircling all orthogonal projections IPorthof all impact points on plane P. As mentioned above with respect to CH(Sk), it is noted that the definition of CA(Sk) also does not depend on the object which is currently imaged.

As shown inFIG.5, the circumscribed orthogonal projection IPorthof all impact points IP on plane P is circle500. The diameter of this circle500defines CA(Sk).

Detailed optical data and surface data are given in tables below for ten lens (or lens assembly) examples (embodiments) numbered as Ex1, Ex2, . . . Ex 10. The ten lens assembly embodiments Ex1 to Ex10 are also shown in, respectively,FIGS.2,6,7,8,9,10,11,12,13and14.

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 S1of 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 S2Nto 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 S1of the first lens element and the clear aperture of the first surface S3of the second lens element, CA(S1)/CA(S3).Focal length of each lens element, fi.
Surface Parameters 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 Ex 1, 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+1.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 Ex 1, Ex2, . . . Ex 10.

Surface Types

z=c⁢r21+1-(1+k)⁢c2⁢r2+Dcon⁡(u)Dcon⁡(u)=u4⁢∑n=0N⁢An⁢Qncon⁡(u2)u=rrma⁢⁢x,x=u2Q0con⁡(x)=1⁢⁢Q1con=-(5-6⁢x)⁢⁢Q2con=1⁢5-1⁢4⁢x⁡(3-2⁢x)Q3con=-{3⁢5-1⁢2⁢x⁡[1⁢4-x⁡(2⁢1-1⁢0⁢x)]}Q4con=7⁢0-3⁢x⁢{1⁢6⁢8-5⁢x⁡[8⁢4-1⁢1⁢x⁡(8-3⁢x)]}Q5con=-[1⁢2⁢6-x⁡(1⁢2⁢6⁢0-1⁢1⁢x⁢{4⁢2⁢0-x⁡[7⁢2⁢0-1⁢3⁢x⁡(4⁢5-1⁢4⁢x)]})]
where {z, r} are the standard cylindrical polar coordinates, c is the paraxial curvature of the surface, k is the conic parameter, rmaxis one half of the surfaces clear aperture, and Anare the polynomial coefficients shown in lens data tables.b) Even aspheric surfaces formula:

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

z=c⁢r21+1-(1+k)⁢c2⁢r2+A1⁢r4+A2⁢r6+A3⁢r8+A4⁢r1⁢0+A5⁢r1⁢2+A6⁢r1⁢4+A7⁢r1⁢6
where “z” is the position of the profile of the surface Skmeasured along optical axis103(coinciding with the Z axis, wherein z=0 corresponds to the intersection of the profile of the surface Skwith the Z axis), “r” is the distance from optical axis103(measured along an axis which is perpendicular to optical axis103), “K” is the conic coefficient, c=1/R where R is the radius of curvature, and An(n from 1 to 7) are coefficients given in Tables 2 and 4 for each surface Sk. 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 1 km from the system, considered to be an infinite distance.

Lines “1” to “8” of Tables 1 to 4 describe respectively parameters associated to surfaces S1to S8. Lines “1” to “10” of Tables 5 to 8 describe respectively parameters associated with surfaces S1to S10.

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 surfaces205a,205bof optical element205and of a surface202aof the image sensor202.

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 Siand surface Si+1, measured along the optical axis103(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 surface202a.

TABLE 1EFL13.809TTL13.612F/#2.735SDL/22.930BFL4.932TTL/EFL0.986BFL/TTL0.362CA(S1)/CA(S3)1.310T(AS to S3)/TTL0.204SDL/CA(S2N)1.503f15.594f2−4.823f39.088f4−10.440

TABLE 4EFL15.001TTL14.472F/#2.727SDL/22.930BFL7.617TTL/EFL0.965BFL/TTL0.526CA(S1)/CA(S3)1.408T(AS to S3)/TTL0.157SDL/CA(S2N)1.577f16.359f2−4.495f348.439f49.909f5−20.537

TABLE 7EFL10.911TTL10.585F/#2.819SDL/22.620BFL5.000TTL/EFL0.970BFL/TTL0.472CA(S1)/CA(S3)1.212T(AS to S3)/TTL0.113SDL/CA(S2N)1.678f14.519f2−3.153f33.343f4−5.268f5−35.623

TABLE 10EFL12.166TTL11.856F/#2.704SDL/22.620BFL6.382TTL/EFL0.975BFL/TTL0.538CA(S1)/CA(S3)1.277T(AS to S3)/TTL0.129SDL/CA(S2N)1.685f15.426f2−2.822f33.047f4−7.208f5−27.026

TABLE 13EFL12.020TTL11.216F/#2.671SDL/22.620BFL6.412TTL/EFL0.933BFL/TTL0.572CA(S1)/CA(S3)1.388T(AS to S3)/TTL0.138SDL/CA(S2N)1.692f14.681f2−4.152f334.206f411.682f5−12.516

TABLE 16EFL15.000TTL14.507F/#2.727SDL/22.930BFL6.750TTL/EFL0.967BFL/TTL0.465CA(S1)/CA(S3)1.361T(AS to S3)/TTL0.103SDL/CA(S2N)1.581f16.186f2−4.313f34.578f4−7.114f5−48.010

TABLE 19EFL16.142TTL14.963F/#2.612SDL/22.930BFL7.459TTL/EFL0.927BFL/TTL0.498CA(S1)/CA(S3)1.489T(AS to S3)/TTL0.160SDL/CA(S2N)1.635f18.251f2−3.476f35.637f4−5.582f55.558

TABLE 22EFL14.955TTL14.056F/#2.690SDL/22.930BFL6.566EFL0.940BFL/TTL0.467CA(S1)/CA(S3)1.489T(AS to S3)/TTL0.171SDL/CA(S2N)1.811f17.731f2−4.271f38.905f46.428f5−6.636

TABLE 25EFL11.190TTL11.135F/#2.590SDL/22.620BFL4.303TTL/EFL0.995BFL/TTL0.386CA(S1)/CA(S3)1.195T(AS to S3)/TTL0.191SDL/CA(S2N)1.638f14.559f2−3.894f37.111f4−8.492

TABLE 28EFL7.970TTL7.780F/#2.148SDL/22.930BFL3.266TTL/EFL0.976BFL/TTL0.420CA(S1)/CA(S3)1.076T(AS to S3)/TTL0.039SDL/CA(S2N)1.580f13.986f2−5.312f3−760.018f432.416f5−70.342

Sign of refractive elements:

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”: AA1≡BFL/TTL>0.35, AA2≡BFL/TTL>0.4, AA3≡BFL/TTL>0.5;“BB”: BB1≡CA(S1)/CA(S3)>1.2, BB2≡CA(S1)/CA(S3)>1.3, BB3≡CA(S1)/CA(S3)>1.4;“CC”: CC1≡T(AS to S3)/TTL>0.1, CC2≡T(AS to S3)/TTL>0.135, CC3≡T(AS to S3)/TTL>0.15;“DD”: At least two gaps that comply with DD1≡STD<0.020, DD2≡STD<0.015, DD3≡STD<0.010;“EE”: At least 3 gaps that comply with EE1≡STD<0.035, EE2≡STD<0.025, EE3≡STD<0.015;“FF”: At least 4 gaps that comply with FF1≡STD<0.050, FF2≡STD<0.035, FF3≡STD<0.025;“GG”: GG1≡SDL/CA(S2N)>1.5, GG2≡SDL/CA(S2N)>1.55, GG3≡SDL/CA(S2N)>1.6;“HH”: a power sign sequence;“II”: At least 1 gap that complies with II1≡STD<0.01 and OA_Gap/TTL<1/80, II2≡STD<0.015 and OA_Gap/TTL<1/65;“JJ”: JJ1: Abbe number sequence of lens elements L1, L2and L3can be respectively larger than 50, smaller than 30 and larger than 50;JJ2: Abbe number sequence of lens elements L1, L2and L3can be respectively larger than 50, smaller than 30 and smaller than 30;“KK”: KK1≡|f2/f1|>0.4 and Abbe number sequence of lens elements L1, L2and L3can be respectively larger than 50, smaller than 30 and smaller than 30; KK2≡|f2/f1|<0.5 and Abbe number sequence of lens elements L1, L2and L3can be respectively larger than 50, smaller than 30 and larger than 50; and“LL”: LL1≡f1/EFL<0.55, LL2≡f1/EFL<0.45;“MM”: MM1≡|f2/f1|<0.9, MM2|f2/f1|<0.5; and“NN”: NN1≡TTL/EFL<0.99, NN2≡TTL/EFL<0.97, NN3≡TTL/EFL<0.95.“OO”: At least two gaps that comply with OO1≡STD>0.020, OO2≡STD>0.03, OO3≡STD>0.040;“PP”: At least 3 gaps that comply with PP1≡STD>0.015, PP2≡STD>0.02, PP3STD>0.03;“QQ”: At least 4 gaps that comply with QQ1≡STD>0.015, QQ2≡STD>0.02, QQ3≡STD>0.03;“RR”: At least 3 OA_Gaps that comply with RR1≡TTL/Min_Gap>50, RR2≡TTL/Min_Gap>60, RR3≡TTL/Min_Gap>100.

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.