Related Applications

[0001] The present application claims the benefit of U.S. Provisional Patent Application Serial No. 61/154,685, filed February 23, 2009 under Attorney Docket No. T0450.70044US00, and entitled "LENS ASSEMBLY," which application is hereby incorporated herein by reference in its entirety.

Background

Field

[0002] The technology described herein relates to lens assemblies.

Related Art

[0003] Designing lens assemblies for imaging objects often involves balancing competing constraints. Firstly, some characteristics of optical performance compete against others, thus making it difficult to achieve a lens assembly that meets two or more competing characteristics of optical performance. Field of view and distortion are two such characteristics, as a larger field of view generally results in a larger degree of distortion. In addition, the desired optical performance of the lens assembly may have to be compromised because of considerations regarding size of the lens assembly, number of lens elements, materials to be used for the lens elements, ease of manufacturing of any particular lens and/or the lens assembly, and compatibility requirements with additional components including filters, aperture stops, and detectors.

Summary

[0004] According to one aspect of the present invention, a lens assembly provides a horizontal field of view (HFOV) of approximately 40 degrees, a distortion of less than approximately 2% for the HFOV, and is compatible with a detector having a diagonal size less than approximately one-half of an inch. The lens assembly comprises, in order from an object side to an image side: a first lens, the first lens being a negative meniscus lens; a second lens, the second lens being a meniscus lens, wherein the first and second lenses are disposed to define an air gap therebetween and wherein the first lens, air gap, and second lens in combination provide a negative optical power; a third lens, the third lens being a biconvex lens having a positive optical power; a first cemented doublet comprising a fourth lens and a fifth lens; a second cemented doublet comprising a sixth lens and a seventh lens, the sixth lens being a biconvex lens having a negative optical power and the seventh lens being a biconvex lens having a positive optical power; an eighth lens; and a ninth lens.

[0005] According to another aspect of the present invention, a lens assembly comprises a plurality of lenses configured to provide a horizontal field of view (HFOV) of approximately 40 degrees and a distortion of less than approximately 2% for the HFOV. The plurality of lenses is configured to produce an image compatible with a detector having a diagonal dimension of less than approximately one-half of an inch.

[0006] According to another aspect of the present invention a lens assembly comprises nine lenses arranged in seven lens groups, an aperture stop, and two filter plates, and conforms to the following prescription. The listed radii of curvature are in millimeters and distances between adjacent surfaces are in millimeters, and the surfaces are numbered from an object side of the lens assembly to an image side of the lens assembly, the first surface corresponding to an object side surface of a first lens element of the lens assembly.

LENS RADIUS OF DISTANCE BETWEEN ABBE REFRACTIVE

SURFACES CURVATURE ADJACENT SURFACES NUMER INDEX

1 -92 0.475 55.20 1.67790

2 7.15 2.000

3 -13.12 2.254 25.36 1.80518

4 -12.57 0.406

5 11.31 1.840 55.41 1.69680

6 -18.10 0.053

7 5.88 1.820 49.83 1.61773

8 -22.00 0.510 33.85 1.64769

9 7.5 1.330

10 Stop 0.630

11 -7.5 1.300 25.36 1.80518

12 6.95 2.060 63.48 1.62014

13 -6.45 0.020

14 12.00 1.705 40.76 1.88300

15 -18.60 0.760

16 -5.69 0.475 50.88 1.65844

17 -14.76 2.043

18 Infinity 0.350 64.17 1.51680

19 Infinity 0.750 64.17 1.51680 20 Infinity 1.190

[0007] According to another aspect of the present invention, a lens assembly comprises nine lenses arranged in seven lens groups, an aperture stop, and two filter plates, and conforms to the following prescription. The listed radii of curvature are in millimeters and distances between adjacent surfaces are in millimeters, and the surfaces are numbered from an object side of the lens assembly to an image side of the lens assembly, the first surface corresponding to an object side surface of a first lens element of the lens assembly.

LENS RADIUS OF DISTANCE BETWEEN ABBE REFRACTIVE

SURFACES CURVATURE ADJACENT SURFACES NUMER INDEX

1 Infinity 0.480 36.00 1.66446

2 6.00 2.266

3 -22.65 2.550 25.36 1.80518

4 -17.78 1.776

5 13.38 2.000 55.41 1.69680

6 -13.38 0.011

7 5.73 1.600 43.72 1.60568

8 Infinity 0.475 38.03 1.60342

9 6.45 0.849

10 Stop 1.841

11 -7.40 1.140 25.36 1.80518

12 6.77 2.000 63.48 1.62014

13 -6.77 0.020

14 14.74 1.600 40.76 1.88300

15 -14.74 0.771

16 -5.44 0.475 50.88 1.65844

17 -10.20 0.995

18 Infinity 2.300 64.17 1.51680

19 Infinity 0.100

20 Infinity 0.750 64.17 1.51680

21 Infinity 1.000 Brief Description of the Drawings

[0008] Description of various aspects and embodiments of the invention will be given by reference to the following drawings. The drawings are not necessarily drawn to scale. Each identical or nearly identical component illustrated in multiple drawings is illustrated by a like numeral.

[0009] FIG. 1 illustrates a lens assembly having nine lens elements arranged in seven lens groups, and providing a 40 degree horizontal field of view (HFOV), together with a filter stack, according to one embodiment.

[0010] FIG. 2 illustrates a perspective view of the lens assembly of FIG. 1.

[0011] FIG. 3 illustrates a lens assembly having nine lens elements arranged in seven lens groups together with a filter stack, and providing a 40 degree HFOV, according to one embodiment.

[0012] FIG. 4 illustrates a cross-sectional view and an end-view of a housing in which a lens assembly like that shown in FIG. 1 may be disposed, according to one embodiment.

[0013] FIG. 5 A illustrates an exterior view of a portion of an imaging device to which the housing of FIG. 4 may be mated, according to one embodiment.

[0014] FIG. 5B illustrates a cross-sectional view of the portion of the imaging device shown in FIG. 5 A with the lens elements of lens assembly 100 disposed within the housing of FIG. 4.

Detailed Description

[0015] Lens assemblies providing beneficial optical performance are described. According to one aspect of the present invention, lens assemblies are provided which exhibit a horizontal field of view (HFOV) of approximately 40 degrees (i.e., +/- approximately 20 degrees, which is sometimes notated herein as ω = 20 degrees) and distortion of less than or equal to approximately 2% for the HFOV, and which are compatible with small detectors/sensors. A horizontal field of view of approximately 40 degrees is approximately equal to a field of view (FOV) of 50 degrees. According to some aspects, the lens assemblies are also high speed/high sensitivity, for example having an f-number of less than or equal to approximately f/2. According to some embodiments, the lens assembly may also provide sufficiently high resolution to be used with a megapixel imaging array.

[0016] According to some aspects of the present invention, lens assemblies exhibiting the above-described optical performance metrics (e.g., a HFOV of approximately 40 degrees and less than or equal to approximately 2% distortion for the HFOV) may be used to produce an image of a scene on a screen/monitor that realistically portrays what a viewer would see if the viewer was viewing the imaged scene directly. According to some embodiments, images may be produced on a screen/monitor inside a vehicle to portray the surroundings of the vehicle. The image on the screen/monitor may accurately represent the vehicle's surroundings as if the viewer was visualizing the surroundings directly, rather than viewing the surroundings on a screen inside the vehicle. Moreover, lens assemblies as described herein providing distortion of less than approximately 2% for a HFOV may facilitate accurate measurement of distances and sizes within an imaged scene, irrespective of where within the resulting image the object(s) of interest appears, since distances toward the edge of the field of view may be substantially the same as those toward the center of the field of view for such low distortion.

[0017] The aspects of the invention described above, as well as additional aspects, will now be described below in further detail. It should be appreciated that these aspects may be used alone, all together, or in any combination of two or more.

[0018] According to one aspect of the present invention, a lens assembly provides a HFOV of approximately 40 degrees with low distortion (e.g., less than approximately 2% distortion, less than approximately 1.5% distortion, less than approximately 0.5% distortion, or any other suitable amount of distortion) for the HFOV. It should be appreciated that when a percentage distortion is listed herein it refers to an absolute value (i.e., including positive and negative values) unless the context indicates otherwise. For example, less than 2% distortion refers to the absolute value of the distortion being less than 2% unless the context indicates otherwise. The lens assembly may be compatible with a miniature detector (e.g., a detector having a diagonal dimension, also referred to herein as a "diagonal length," of less than or equal to approximately one-half of an inch, less than or equal to approximately 1/3 inch, less than or equal to approximately ¹ Zi inch, or any other suitable size) of standard resolution (i.e., 640X480 pixels) or megapixel resolution, meaning that the lens assembly may produce at an image plane an image having a width substantially equal to the width of the detector. Although the present aspect of the invention is not limited to any particular physical configuration for the lens assembly, a non-limiting example is illustrated in FIG. 1.

[0019] As shown, the lens assembly 100 comprises nine lenses 102a-102i (having respective thicknesses D1-D9) arranged in seven lens groups and configured to form an image at the image plane 104. As also shown, and as will be described further below, an aperture stop 106 may be disposed between the lenses of the lens assembly 100, and in the non-limiting example of FIG. 1 is disposed between the fifth and sixth lenses (i.e., lenses 102e and 102f).

[0020] The lenses 102a-102i may have any suitable sizes, radii of curvature, materials, indices of refraction, and relative positioning within the lens assembly to provide the lens assembly a HFOV of approximately 40 degrees and distortion of less than or equal to approximately 2% for the HFOV (which may correspond to distortion of less than or equal to approximately 2.7% across the FOV of approximately 50 degrees), non-limiting examples of which will be described further below. Yet, certain attributes of the lenses may generally be described as follows.

[0021] Lens 102a, which may be intended to be closest to an object to be imaged when the lens assembly 100 is in use, may be a negative meniscus lens. According to one embodiment, the lens 102a is made of a crown glass having a high index of refraction, and in one embodiment is made of a Lanthanum crown glass, although not all embodiments are limited to these materials. Furthermore, the lens 102a may have a relatively small thickness Dl at its center.

[0022] Lens 102b may have a low optical power according to one embodiment, and therefore may have any suitable shape and/or material for generating a low optical power. According to one embodiment, lens 102b is a meniscus lens comprising dense flint, and having a relatively thick center thickness D2. Other materials and shapes for lens 102b are also possible.

[0023] According to one embodiment, and as illustrated, lenses 102a and 102b are configured to form an air gap 108 therebetween. The shapes and spacing of lenses 102a and 102b, and therefore the resultant shape and size of the air gap 108 therebetween, may be designed in one embodiment such that the combination of lens 102a, lens 102b, and air gap 108 exhibits a combined negative optical power. Such behavior may increase the field of view provided by the lens assembly 100, and may, for example, provide the lens assembly 100 with a greater field of view than may be obtained using a conventional double gauss lens assembly. However, not all embodiments are limited in this respect.

[0024] As illustrated in FIG. 1, lens 102c may be a biconvex lens according to one embodiment. It may provide a positive optical power. According to one embodiment lens 102c comprises crown glass having a high index of refraction, and in one embodiment is a Lanthanum crown biconvex lens, although not all embodiments are limited to these materials. According to one embodiment, lens 102c may be substantially similar to the first most element typically found in a conventional double gauss lens assembly. However, not all embodiments are limited in this respect.

[0025] As illustrated, lenses 102d and 102e form a cemented doublet in the non- limiting example of lens assembly 100. According to one embodiment, lens 102d comprises a crown glass (which in some embodiments may be a Barium crown glass) having a high index of refraction and lens 102e comprises flint. The cemented doublet formed by lenses 102d and 102e may, in one embodiment, be substantially similar to or the same as the first most doublet typically found in a conventional double gauss lens assembly. However, not all embodiments are limited in this respect.

[0026] Lenses 102f and 102g form a second cemented doublet, according to the non- limiting example of lens assembly 100. Lens 102f may be a biconvex lens providing a negative optical power according to one non-limiting embodiment, and may, in one embodiment, be formed of a dense flint. Lens 102g may be a biconvex lens providing an optical power opposite to that provided by lens 102f. For example, lens 102g may provide a positive optical power in those embodiments in which lens 102f provides a negative optical power. According to one embodiment, lens 102g comprises crown glass (which in some embodiments may be medium index crown glass) having a high index of refraction and low dispersion. According to one embodiment, the cemented doublet formed by lenses 102d and 102e and the cemented doublet formed by lenses 102f and 102g may be approximately symmetrical with respect to the aperture stop 106. However, not all embodiments are limited in this respect, as, for example, the cemented doublet formed by lenses 102d and 102e may be spaced closer to or farther from the aperture stop 106 than the second cemented doublet formed by lenses 102f and 102g. [0027] As illustrated, lens 102h may be a biconvex lens according to one embodiment, and may, in one embodiment, be formed of dense Lanthanum flint with medium dispersion. In one embodiment, lens 102h may comprise crown glass having a high index of refraction, and in an alternative embodiment it may comprise flint having a high index of refraction.

[0028] Lens 102i may be designed to flatten the field of the image produced by lens assembly 100, and may therefore facilitate reduction of distortion created by the other lenses of the lens assembly 100. Thus, lens 102i may have any suitable shape, position and material for doing so. According to one non- limiting embodiment, lens 102i comprises crown glass having a high index of refraction. According to one embodiment, lens 102i comprises extra dense crown glass having a medium index of refraction. However, other materials may alternatively be used.

[0029] According to some embodiments, lens assemblies as described herein may optionally be used in combination with a filter stack having one or more filter plates. For example, the lens assembly 100 of FIG. 1 may optionally include a filter stack formed by filter plates 102j and 102k, which may be any suitable type of filter plates (having any suitable thickness and material) for providing a desired filtering function. Again, such filter stacks may be optional.

[0030] Table I provides a non-limiting prescription for lens assembly 100 conforming to the above-described characteristics, and therefore which may provide a HFOV of approximately 40 degrees (i.e., 2ω is approximately equal to 40 degrees) with less than or equal to approximately 2% distortion, and which also may be compatible with a small detector, as described further below. In particular, the prescription of Table I is scaled for operation of the lens assembly with a 1/3 inch detector (i.e., a detector having a diagonal length of 1/3 of an inch). It should be appreciated that the prescription may be modified or scaled for use with detectors of other sizes. In addition, the prescription of Table I may provide a substantially constant focus. It should be appreciated that other prescriptions are also possible, as Table I merely represents one non-limiting example of a prescription conforming to the foregoing description of lens assembly 100.

[0031] For purposes of Table I, the prescription provides a focal length F of approximately 6.81mm with an f-number (shown as "F NO") of approximately 2. The lens surfaces are numbered according to the configuration of FIG.1 , with surface number 1 corresponding to the object side surface of lens 102a, surface number 2 corresponding to the image side surface of lens 102a, and so on. The listed radii of curvature and distances between adjacent surfaces are in millimeters.

Table I: Example Prescription of Lens Assembly 100

F = 6.81

F NO = 2

2ω = 40°

LENS RADIUS OF DISTANCE BETWEEN ABBE REFRACTIVE

SURFACES CURVATURE ADJACENT SURFACES NUMER INDEX

1 -92 0.475 55.20 1.67790

2 7.15 2.000

3 -13.12 2.254 25.36 1.80518

4 -12.57 0.406

5 11.31 1.840 55.41 1.69680

6 -18.10 0.053

7 5.88 1.820 49.83 1.61773

8 -22.00 0.510 33.85 1.64769

9 7.5 1.330

10 Stop 0.630

11 -7.5 1.300 25.36 1.80518

12 6.95 2.060 63.48 1.62014

13 -6.45 0.020

14 12.00 1.705 40.76 1.88300

15 -18.60 0.760

16 -5.69 0.475 50.88 1.65844

17 -14.76 2.043

18 Infinity 0.350 64.17 1.51680

19 Infinity 0.750 64.17 1.51680

20 Infinity 1.190

[0032] As previously mentioned, according to one aspect of the present invention lens assemblies providing a HFOV of approximately 40 degrees and less than approximately 2% distortion may also be compatible with a miniature detector. Referring again to FIG. 1 , the detector may be disposed at the image plane 104. The detector may have a small size, for example having a diagonal dimension less than or equal to approximately one half of an inch, less than or equal to approximately one third of an inch, less than or equal to approximately one quarter of an inch, or any other suitable dimension. The detector may be a complementary metal oxide semiconductor (CMOS) detector, a charge coupled device (CCD) detector, or any other suitable detector, as the various aspects described herein are not limited to the type of detector used.

[0033] According to one embodiment, the detector may comprise an imaging array (e.g., an array of light sensitive pixels). According to one embodiment, the detector may be a standard imaging array, for example having an array of 640X480 pixels. According to another embodiment, lens assemblies according to the present invention may be compatible with detectors of substantially higher resolution. For example, according to one embodiment lens assemblies according to the various aspects described herein (e.g., lens assembly 100 of FIG. 1) may be compatible with megapixel imaging arrays (i.e., imaging arrays having more than one million pixels). According to one embodiment, lens assembly 100 may be compatible with a detector comprising between three to five megapixels, although other numbers of pixels are also possible. To facilitate compatibility of the lens assembly 100 with a megapixel detector, a 0.35mm thick window with a dichroic thin film near infrared (IR) blocking coating may be positioned between the lens assembly and the image plane (e.g., between lens 102i and image plane 104), according to one non-limiting embodiment together with an optical window covering the detector.

[0034] In addition to providing a desirable horizontal field of view, low distortion, and compatibility with a small detector, lens assemblies according to the various aspects described herein may provide one or more additional features. For example, according to one aspect of the present invention a lens assembly providing a HFOV of approximately 40 degrees, distortion of less than or equal to approximately two percent for the HFOV, and being compatible with a small detector (e.g., having a diagonal dimension of less than approximately one-half of an inch), may additionally provide high sensitivity characterized by an f-number less than or equal to approximately f2.0 (e.g., fl.8, fl.6, fl.4, or any other suitable f-number). Referring again to FIG. 1, the aperture stop 106 positioned between the two cemented doublets of the lens assembly 100 may have any suitable diameter to provide an f-number of less than or equal to approximately f2.0. In this manner, the lens assembly may be a fast lens assembly, allowing for high speed operation of any device (e.g., a camera) using the lens assembly.

[0035] According to another aspect of the present invention, the lens assembly may provide a HFOV of approximately 40 degrees, distortion of less than approximately two percent for the HFOV, may be compatible with a small detector, and additionally may be compact. A compact design for the lens assembly may facilitate its use in certain environments and/or devices with limited space. According to one embodiment, the lens assembly may have an axial length of approximately 22 mm (e.g., 21.6 mm or any other suitable length). Other lengths are also possible, and the various aspects described herein are not limited to lens assemblies having any particular axial length. According to one embodiment, the axial length may be selected to facilitate placing the lenses of the lens assembly within a housing having particular size limitations, as will be described further below. According to one embodiment, the largest diameter of any of the lenses 102a- 102i may be less than approximately 10mm. Other sizes are also possible, as the lens assembly 100 and lenses thereof are not limited to any particular sizes.

[0036] The lens assembly 100 may provide for various adjustments to be made, for example by a user. According to one embodiment, one or more of the focus, focal length, and aperture of the lens assembly may be adjusted manually by a user. According to another embodiment, one or more of the focus, focal length, and aperture of the lens assembly may be controlled electromechanically or piezoelectrically, for example using a stepping piezo motor controlled by a processor (e.g., a microprocessor), which in one embodiment may store processor executable instructions which, when executed by the processor, cause the stepping piezo motor to adjust the focus, focal length, and/or aperture. Other manners of control of the focus, focal length, and aperture are also possible, as these are non-limiting examples.

[0037] According to one embodiment, the lens assembly 100 may additionally provide a constant focus or a substantially constant focus. For example, the lens assembly may be used with an f-number consistent with constant focus. Thus, according to one aspect of the present invention, a lens assembly is provided which has a HFOV of approximately 40 degrees, less than or equal to approximately 2% distortion for the HFOV, is compatible with a detector having a diagonal length less than or approximately equal to one-half of an inch, and provides a constant focus.

[0038] FIG. 2 illustrates a perspective view of the lens assembly 100 of FIG. 1, showing the seven lens groups of FIG. 1 absent the optional filter plates 102j and 102k. Because the figure illustrates lens groups, the boundaries between lenses 102d and 102e and between lenses 102f and 102g are not shown in FIG. 2. [0039] As mentioned previously, it should be appreciated that lens assemblies according to the various aspects of the present invention may include or be used in combination with various additional components. For example, the lens assemblies may be used in combination with one or more filters, such as the optional filter plates 102j and 102k of FIG. 1. The one or more filter plates may be disposed between an image plane of the lens assembly and the lens of the lens assembly closest to the image plane. FIG. 3 illustrates another non-limiting example.

[0040] As shown in FIG. 3, the lens assembly 300 may be substantially the same as lens assembly 100 of FIG. 1 (including lenses 102a-102i) with the addition of a filter stack 302 formed by filter plates 304a and 304b. The filter stack may comprise one or more filter plates and in some embodiments may have a gap between two or more such filter plates. According to one embodiment, the lens assembly may be configured for use with a megapixel detector, and the filter stack 302 may comprise a near infrared (IR) cut filter. According to another embodiment, the lens assembly 300 may be configured for use with a NTSC/PAL detector, and the filter stack 302 may comprise a near IR cut filter and a low pass quartz filter. According to one embodiment, the filter stack comprises a Sentech 3.45mm thick filter. However, the exact size and material of the filter stack 302 is not limiting, and may be chosen to provide a desired filtering function. According to one embodiment, the filter stack 302 may comprise one or more Schott KG filters. Other types and numbers of filters may alternatively be used.

[0041] The lens assembly 300 may provide some or all of the optical performance characteristics of lens assembly 100. For example, the lens assembly 300 may have a HFOV of approximately 40 degrees (i.e., +/-20 degrees), less than or equal to approximately 2% distortion for the HFOV, and may be compatible with small detectors (e.g., having a diagonal dimension less than or equal to approximately one-half of an inch). Table II illustrates a non-limiting prescription for the lens assembly 300, which may minimize any aberrations introduced by the filter stack.

[0042] For purposes of Table II, the prescription provides a focal length F of approximately 6.55mm with an f-number (shown as "F NO") of approximately 2. The lens surfaces are numbered according to the configuration of FIG.3, with surface number 1 corresponding to the object side surface of lens 102a, surface number 2 corresponding to the image side surface of lens 102a, and so on. The listed radii of curvature and distances between adjacent surfaces are in millimeters.

Table II: Example Prescription of Lens Assembly 300

F = 6.55

F NO = 2

2ω = 40°

LENS RADIUS OF DISTANCE BETWEEN ABBE REFRACTIVE

SURFACES CURVATURE ADJACENT SURFACES NUMER INDEX

1 Infinity 0.480 36.00 1.66446

2 6.00 2.266

3 -22.65 2.550 25.36 1.80518

4 -17.78 1.776

5 13.38 2.000 55.41 1.69680

6 -13.38 0.011

7 5.73 1.600 43.72 1.60568

8 Infinity 0.475 38.03 1.60342

9 6.45 0.849

10 Stop 1.841

11 -7.40 1.140 25.36 1.80518

12 6.77 2.000 63.48 1.62014

13 -6.77 0.020

14 14.74 1.600 40.76 1.88300

15 -14.74 0.771

16 -5.44 0.475 50.88 1.65844

17 -10.20 0.995

18 Infinity 2.300 64.17 1.51680

19 Infinity 0.100

20 Infinity 0.750 64.17 1.51680

21 Infinity 1.000

[0043] According to one aspect of the present invention, lens assemblies as described herein may be housed. The housing may be designed in terms of material, shape, size, and mating features (e.g., threads, slots, notches, etc.) to facilitate use of the lens assembly, for example in combination with other components of a device. According to one embodiment a housed lens assembly may form at least part of a camera or other imaging device.

[0044] FIG. 4 illustrates both a cross-sectional view (top of figure) and an end-view (bottom of figure), i.e., viewing the housing end-on, of a non-limiting example of a housing in which a lens assembly like that shown in FIG. 1 may be disposed, according to one embodiment. It should be appreciated that other housing configurations are also possible, and that the various aspects of the technology described herein are not limited to using any particular type, shape, or sizing of housing to hold the lens assemblies described herein, or to using a housing at all.

[0045] As shown in FIG. 4, the housing 400 includes an outer surface 402 and four inner chambers 404a-404d. The lenses 102a-102i of lens assembly 100 may be disposed within the chambers 404a-404d in any suitable manner, and in some embodiments are distributed between chambers 404a-404c. For example, according to one embodiment, lenses 102a- 102c may be disposed at least partially within chamber 404a, lenses 102d- 102e may be disposed at least partially within chamber 404b, and lenses 102f-102i may be disposed at least partially within chamber 404c. According to one embodiment, a filter plate may be disposed in chamber 404d. However, this is merely one non-limiting example of an arrangement of lenses 102a-102i within a housing, and other arrangements are also possible.

[0046] The housing 400 may have any suitable dimensions for holding the lenses and for interconnecting with any additional components of interest (e.g., lens covers, or other components of a camera or other imaging device). According to one embodiment, the housing has a total length L of approximately 18mm (e.g., 17.75mm). The outer surface 402 may have a diameter of approximately 12mm. Chamber 404a may have a diameter of approximately 8mm. Chamber 404b may have a diameter of approximately 6.5mm. Chamber 404c may have a diameter of approximately 6mm. Chamber 404d may have a diameter of approximately 5.5mm. Other dimensions are also possible, as these non- limiting examples of suitable dimensions are provided for purposes of illustration only.

[0047] According to one embodiment, the lens assembly 100 (or 300) and/or the housing 400 has an axial length of less than 21.5 mm. The lens assembly may also provide a HFOV of approximately 40 degrees, less than or equal to approximately 2% distortion for the HFOV, and may also have an f-number of less than or equal to fl .8.

[0048] As mentioned, the housing 400 may be configured to mate or interconnect with one or more additional components. For example, according to one embodiment, a lens cover, filter, or other optical component may be positioned over the end of housing 400 nearest chamber 404a, as will be understood further from FIG. 5B, described below. Accordingly, the outer surface 402 may have threading over a portion or all of its length to facilitate engagement with the lens cover, filter, or other components. According to one embodiment, the end of housing 400 nearest chamber 404d may be mated to a camera body, for example by threading into a receiving portion of the camera body. Accordingly, threads or any other suitable engagement feature (e.g., notches, slots, etc.) may be provided on the housing 400 to facilitate such interconnection.

[0049] FIGs. 5A and 5B illustrate an exterior and a cross-sectional view, respectively of a portion of a camera 500 in which the housing 400 of FIG. 4 may be disposed. As shown, the portion 502 of the camera may have a receiving portion 504 into which the housing 400 may be threaded, as indicated by the threading on the outer surface of the housing 400 and on the inner surface of the receiving portion 504. In this manner, the lens assembly 100 may be aligned with a detector of the camera 500, which may be, for example, positioned at or approximately at an image plane corresponding to the lens assembly. The distance between the housing 400 and the detector (e.g., a CCD detector) when the housing is inserted into the receiving portion 504 may take any suitable value, and may be formed of air, filter plates, some combination of the two, or any other suitable material. According to one embodiment, the distance from housing 400 to the detector may be approximately four millimeters (e.g., 3.8mm, 4.1mm, or any other suitable value) in air. According to an alternative embodiment, approximately two millimeters worth of filter plates may be disposed between the housing 400 and the detector, with an additional distance of approximately 2.5mm of air between the housing 400 and the detector. Other distances and relative positions between the housing 400 and a detector of the camera 500 are also possible.

[0050] In the illustrated embodiment, a lens cover 506 is threaded over an end of the housing 400. The lens cover may function as a filter, may provide protection for the lens assembly, or may serve any other function, as the embodiment illustrated in FIGs. 5A and 5B is not limited in this respect.

[0051] Having thus described several aspects of at least one embodiment, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be within the spirit and scope of the various aspects of the present invention. Accordingly, the foregoing description and drawings represent examples only.