Light shading baffle

Abstract

This application relates to a baffle unit used with optical systems to limit stray light. The baffle is designed around a cylindrical body fitted with a connection adaptor and includes vanes arranged on its inner surface. Their height and position are selected to block light arriving at angles greater than a minimal incident angle θ and to prevent reflections from the inner wall from reaching the optical components. The vane layout includes a front vane and at least one inner vane, with the front vane positioned to shield the inner vane edges from high angle light. An optical system incorporating such a baffle reduces unwanted illumination at the detector. A method for designing the baffle defines the field of view, blocking angle, vane placement, baffle length and diameter, and produces structural parameters suited for integration with a given optical system.

Description

[0001] LIGHT SHADING BAFFLE

[0002] TECHNOLOGICAL FIELD

[0003] The present disclosure is in the field of optical systems and generally relates to optical system utilizing a baffle for reducing glare.

[0004] BACKGROUND

[0005] Optical systems are generally configured for collecting light arriving from a selected field of view and directing the collected light to form an image on a selected image plane, e.g., a detector plane of the system. If light arriving from one or more sources outside of the field of view enters the optical system, such light may scatter from surfaces within the optical system, and reach the detector, adding noise to image collected thereby. This scattered light is generally referred to as stary light.

[0006] To eliminate, or at least reduce amount of stray light entering the system, typical optical systems may utilize one or more field stop apertures. Such field stop apertures prevent light arriving from outside of the field of view from entering the optical system, and thus reducing noise and glare.

[0007] Certain optical systems may require additional elements to eliminate or at least significantly reduce glare and image noise associated with stray light entering the system. A baffle is an optomechanical element often used with optical systems to block unwanted light from entering the system. The baffle actually acts as a shield, blocking light rays originating from regions outside of the field of view from entering the optical system.

[0008] Various baffle configurations are known including e.g.:

[0009] Asadnezhad, M., Eslamimajd, A. & Hajghassem, H. Optical system design of star sensor and stray light analysis. J. Eur. Opt. Soc. -Rapid PubL 14, 9 (2018). (https: / / doi.org / 10.1186 / s41476-018-0078-8) indicating that a star sensor is one of the precise attitude determination sensors. It is an electro-optical system that takes an image from a set of stars and by comparing it with the star catalogue determines angle deviation of the satellite and modifies its attitude. Star sensor is composed of baffle, optical system, detector, and electronic and image processing system.

[0010] CN1502524 relates to a star sensor glare shield. It is formed from first-stage extinction portion and second-stage extinction portion which are connected together. The first-stage extinction portion is divided into high-reflectivity cone face and absorption cone face for replacing out large portion of entered parasitic light or absorbing it and making small portion of scattered beam enter into second-stage extinction portion. The second-stage extinction portion is an absorption cone face, said scattered beam can be absorbed by second-stage extinction portion. Said invention is simple in structure, can effectively track and control propagation path of light, specially, track and control propagation direction of scattered beam.

[0011] CN102243414 describes a reflective star sensor light shield comprises three thin- wall cone barrels, wherein the three thin-wall cone barrels are successively connected. Inner walls of two cone barrels which are far from a lens are smooth clean surfaces and are sprayed with black paint or black films with high reflectivity and a low scattering rate. The inner wall of the cone barrel which is close to the lens is a baffle vane or a barrel type structure of eliminating veiling glare threads and is sprayed with black paint or black films with low reflectivity and the low scattering rate. The whole light shield can possess an optimal length through setting an algebraic relation of cone angles of each cone barrel. The reflective star sensor light shield of the invention has a short length and light weight and is convenient for processing and manufacturing. The reflective star sensor light shield possesses strong inhibition capability for stray light, such as sunlight and ground gas light, which is a strong light source out of field of view. The invention can be used for the star sensor to shade light and be used for optical remote sensors to explore deep space, such as a star camera and the like.

[0012] KR 102081348 relates to a baffle apparatus using a reflective curve vane, to a manufacturing method thereof, and to an imaging device using the same. According to one embodiment of the present invention, the baffle apparatus using a reflective curve vane comprises: a baffle tube having a field of view (FOV) of a baffle preset on one side and an image sensor attached to the other side; and at least one reflective curve vane positioned inside the baffle tube and reflecting an incident ray of a stray ray having an incidence angle exceeding the FOV of the baffle. US 2021 / 407,059 Describes systems and methods for direct sun imaging by a star tracker. Disclosed in a certain example is a direct sun imaging star tracker that includes an imaging sensor and a baffle. The baffle includes a star port, a sun port, and a beam splitter. The star port is configured to image first viewing environment while the sun port is configured to image a second viewing environment that includes the sun. The beam splitter is configured to combine electromagnetic radiation from the star port and the sun port into a combined image. In various examples, the systems and techniques described herein allow a star tracker to simultaneously view both the sun and the stars.

[0013] GENERAL DESCRIPTION

[0014] As indicated above, Baffle units are typically used for blocking undesired light from entering an optical system and introducing noise and glare to collected images. The present disclosure provides a novel baffle configuration, and a corresponding optical system. The baffle according to some embodiments of the present disclosure is configured of an elongated cylindrical body having diameter and length selected in accordance with angular width of field of view (FOV) of the optical system and a minimal blocking angle 0, such that light originating from a source located outside the FOV, and at an angular relation a>0 with respect to optical axis of the optical system, is blocked from entering the optical system.

[0015] Conventional baffle units are typically formed of an elongated cylindrical element having length L>D / tan(6), where D is the baffle diameter at its entrance. Some baffle units further utilize one or more vanes, configured as walls of a selected height extending internally within the baffle unit, and configured to further block undesired light components. The use of one or more vanes along an internal surface of the cylinder structure enables to further reduce stray light. However, in some situations, light components impinging on the edges of the vanes, or on inner surface of the baffle or vanes may scatter from the edges introducing a source of stray light in the system. As described in more detail below, light scattering from edges of the vanes may result in a ring-like source of stray light, while multiple scattering / reflection from inner surfaces may result in an additional source of stray light.

[0016] To solve these issues, the present disclosure provides a baffle unit comprising a main body formed of an elongated tube or cylinder and one or more vanes extending internally from a surface of the elongated body and having selected lengths with respect to baffle dimensions. Each vane is characterized by a wall height and a ring edge defined by edges of the vane. Where height and location of the vanes is selected to block stray light from impinging onto the ring edge of the vanes, or to block light scattered from ring edge of the vanes from entering the optical system.

[0017] In this connection, according to some embodiments, the baffle unit may comprise two or more vanes along the baffle structure. Such two or more vanes comprise a first, entry vane and at least one second vane, located in path between first end of the baffles unit accepting collected light, and second end of the baffle unit being connectable to the optical system. The first vane has height selected to block light components arriving at angle greater than Q from reaching edge of the second vane. Further, the second vane has height and location selected to block light components scattered by edge of the first vane from entering the optical system.

[0018] Thus, according to a first broad aspect, the present disclosure provides a baffle unit for use in association with an optical system, the baffle comprises: a main body formed of a cylindrical member; a connection adaptor positioned at one end of the cylindrical member and configured for connecting to the optical system; and one or more vanes extending from an inner surface of the cylindrical member and configured to reduce stray light rays from entering the optical system; wherein at least height and location of the one or more vanes provide blocking of light components having an incident angle greater than a selected minimal incident angle Q and reflection thereof from the inner surface of the cylindrical member from entering the optical system; and wherein said one or more vanes further comprise at least a first vane being a frontmost vane of the baffle unit and at least one inner vane, location and height of the first vane being selected to block light components having an incident angle greater than the selected minimal incident angle Q from impinging on edges of the at least one inner vane.

[0019] In some configurations, the one or more vanes are configured to block stray light arriving at angular span greater than the minimal angle Q from entering the optical system.

[0020] According to some embodiments, the one or more vanes comprise at least a first vane being the frontmost vane of the baffle unit and at least one inner vane, location and height of the at least one inner vane are selected to block light components originating from edges of the first vane from being entering the optical system.

[0021] According to some embodiments, the location and height of the at least one inner vane are further selected to block light components originating from edges of the first vane from entering the optical system.

[0022] According to some embodiments, inner surfaces of the baffle unit and the one or more vanes are treated with a low reflectivity material or a light absorbing material.

[0023] According to some embodiments, the connection adaptor is configured for selectively connecting the baffle unit to an optical system.

[0024] According to some embodiments, the connection adaptor is configured for permanently connecting the baffle unit to a selected optical system.

[0025] According to some embodiments, the cylindrical member is configured with diameter variation along optical axis thereof.

[0026] According to a second broad aspect, the present disclosure provides an optical system comprising at least one detector, a lens arrangement and a baffle unit positioned for limiting collection of stray light by the lens arrangement; the baffle unit comprises: a main body formed of a cylindrical member; and one or more vanes extending from internal surface of the cylindrical member and configured to reduce stray light rays from entering the optical system; wherein at least height and location of the one or more vanes provide blocking of light components having of an incident angle greater than a selected minimal incident angle Q and reflection thereof from inner surface of the cylindrical member from entering the optical system; and wherein said one or more vanes comprise at least a first vane being a frontmost vane of the baffle unit and at least one inner vane, location and height of the first vane being selected to block light components having incident angle greater than a selected minimal incident angle Q from impinging on edges of the at least one inner vane.

[0027] In some configurations, the one or more vanes are configured to block stray light arriving at angular span greater than the minimal angle Q from entering the optical system.

[0028] According to some embodiments, the optical system is characterized by an angular span of field of view thereof being smaller that the selected minimal blocking angle Q. According to some embodiments, the one or more vanes comprise at least a first vane being the frontmost vane of the baffle unit and at least one inner vane, location and height of the at least one inner vane are selected to block light components originating from edges of the first vane from entering the optical system.

[0029] According to some embodiments, the optical system is configured for low light imaging.

[0030] According to some embodiments, inner surfaces of the cylindrical member and the one or more vanes are treated with a low reflectivity material or a light absorbing material.

[0031] According to some embodiments, the cylindrical member is configured with diameter variation along optical axis thereof.

[0032] According to a third broad aspect, the present disclosure provides a method for designing a baffle unit, the method comprising:

[0033] (a) determining a field of view angular range, a minimal blocking angle 0, and an input aperture of an associated optical system;

[0034] (b) selecting a distance of an inner vane with respect to the input aperture of an optical system;

[0035] (c) determining a length of the baffle unit in accordance with the minimal blocking angle 0 and location of the inner vane;

[0036] (d) determining a minimal diameter of the baffle unit in accordance with shading line defined by location of the inner vane blocking light from entering the input aperture of an optical system;

[0037] (e) defining a structure of the baffle unit in accordance with (a)-(d) and providing output data indicative thereof.

[0038] According to some embodiments, determining a length of the baffle unit comprises determining a length providing shading of an edge of the inner vane with respect to light components having an incident angle greater than the selected minimal blocking angle 0.

[0039] According to some embodiments, determining a minimal diameter of the baffle unit comprises determining a minimal diameter to provide shading of an internal surface of a body of the baffle unit by a first vane.

[0040] According to some embodiments, determining a length of the baffle unit comprises determining a shading line resulting by edge of the inner vane with respect to the minimal blocking angle and input aperture of the optical system. According to some embodiments, said determining a length of the baffle unit comprises: determining a path of a first light ray passing through a location of an edge of the inner vane and reaching an opposite edge of the input aperture; and determining a length of the baffle unit in accordance with a location of intersection of said first light ray with a second light ray arriving an opposite edge of the inner vane and an angle associated with FOV angle with respect to an optical axis.

[0041] According to some embodiments, said determining a minimal diameter of the baffle unit comprises selecting a distance of the location of intersection from the optical axis.

[0042] According to some embodiments, selecting a distance of an inner vane with respect to the input aperture of an optical system comprises selecting a desired length and diameter / radius of the baffle unit.

[0043] The following are definitions for general elements relating to the present disclosure.

[0044] Baffle: A baffle is a structural component used in optical systems to block or absorb stray light that could otherwise reach the detector and degrade the quality of the captured signal. Baffles are strategically placed along the optical path or around the edges of lenses or mirrors to prevent unwanted light from reflecting or scattering into the detector. They typically feature non-refl ective surfaces and may be designed in various shapes, such as tubes, cones, or partitions, to optimize their effectiveness in controlling light paths.

[0045] Vane: A vane in an optical system refers to a flat or angled thin plate used to block or redirect stray light. Vanes are often positioned inside baffles or along the optical path to prevent light from undesired angles from reaching the detector. By creating a series of obstacles for stray light, vanes help ensure that only light from the intended optical path reaches the detector. They are typically coated with non-reflective materials to absorb light and minimize scattering.

[0046] Sunshield: A sunshield is a device or structure designed to block or reflect sunlight or other intense light sources away from sensitive optical components, particularly the detector. Sunshields are crucial in systems exposed to direct sunlight, such as space telescopes or other outdoor optical instruments. By preventing direct sunlight from entering the optical system, sunshields reduce the amount of stray light that could overwhelm or damage the detector. They are often made from highly reflective or thermally insulating materials and may be designed to fold or deploy as needed.

[0047] Stray light: Stray light refers to any unwanted light that enters an optical system and reaches the detector but is not part of the intended optical signal. Stray light can come from various sources, including reflections from surfaces within the optical system, light scattering from dust or imperfections, or external light sources such as the sun. It can degrade the performance of the optical system by reducing contrast, introducing noise, or causing false signals. Controlling stray light is critical in high-precision optical applications to ensure accurate and reliable measurements.

[0048] BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0050] Fig. 1 exemplifies an optical system and a baffle unit;

[0051] Figs. 2A and 2B exemplify a structure of a baffle unit including a vane (Fig. 2A) and the structure of the vane (Fig. 2B)

[0052] Figs. 3A to 3F exemplify steps of designing of a baffle unit according to some embodiments of the present disclosure; Fig. 3A shows determining an inner vane position, Fig. 3B shows determining a baffle length; Fig. 3C shows determining a baffle unit diameter; Fig. 3D shows vanes structure; Fig. 3E shows a baffle unit body; and Fig. 3F illustrates a baffle unit according to some embodiments of the present disclosure;

[0053] Fig- 4 shows calculated length and diameter of the baffle unit in accordance with location of a vane according to some embodiments of the present disclosure;

[0054] Figs. 5A to 5E exemplify steps of designing a baffle unit according to some other embodiments of the present disclosure; Fig. 5A shows determining an inner vane location; Fig. 5B exemplifies the minimal blocking angle; Fig. 5C shows determining a baffle unit length; Fig. 5D exemplifies a baffle configuration; and Fig. 5E compares between baffle configurations in accordance with different locations of inner vane; Fig. 6 illustrates a baffle unit configuration according to some embodiments of the present disclosure; and

[0055] Fig- 7 shows calculation of a baffle unit length and radius in accordance with location of an inner vane according to some embodiments of the present disclosure.

[0056] DETAILED DESCRIPTION OF EMBODIMENTS

[0057] As indicated above, the present disclosure provides an optical system, and a baffle unit configured for blocking or at least significantly reducing stray light from being collected by the optical system. Reference is made to Fig. 1 exemplifying an optical system 100 connected to a baffle unit 50. The optical system 100 in this example includes a main body 110, and a lens body 120. It should however be noted that various optical systems may be used including a camera, a star-light detection / navigation, or any other optical system configured for collecting light from a selected field of view. Generally, the baffle unit 50 and the optical system 100 is illustrated herein as having a cylindrical symmetry. Accordingly, the illustrations in the figures represent a cross section of the cylindrical structure. It should however be noted that the baffle unit may be formed in any selected geometry, and that the technique of the present disclosure typically relates to minimal diameter of the baffle unit, where the baffle unit 50 may be formed with varying diameter, e.g. conical of partially conical shape, where the minimal diameter is determined in accordance with the description below.

[0058] As the optical system 100 is configured with a selected field of view (FOV), the lens body 120 thereof, or any other optical arrangement as the case may be, typically includes at least one aperture, configured for limiting collection of light arriving from outside of the field of view. However, stray light may still enter the lens body, and scatter from one or more surfaces thereof, resulting in some intensity of scattered light entering into the optical system 100. Collection of light components that are outside of the selected FOV of the system may cause noise, or glare in data collected by the optical system 100. This may result in a noisy image, glare in detection of starlight pattern, or various other effects that degrade the quality of data collected by the optical system 100.

[0059] To further reduce collection of stray light, the optical system 100 may be associated with a baffle unit 50. The baffle unit 50 may be configured as an elongated and typically a cylindrical body, configured to block light components originating from locations outside of the FOV of the optical system 100. The baffle unit 50 is configured to provide blocking of light arriving with angle greater than certain selected minimal angle 0 from entering the optical system 100.

[0060] While various baffle structures are known in the art, undesired light components impinging on various elements of the baffle unit may be scattered, resulting in some intensity of stray light being collected by the optical system. Baffle unit 50 is exemplified in Fig. 1, configured as a cylindrical body having length and diameter selected in accordance with a minimal blocking angle 0. Generally, the length and diameter of the baffle unit 50 may be selected to comply with the relation L>D / tan(6), where L is the length and D is the diameter of the baffle unit 50. Accordingly, light components 40 originating from a source outside FOV of the system and arriving at angle 0 or larger, are blocked from entering an input aperture 122 of the optical system 100. An issue with this conventional configuration may relate to reflection and scattering of light from internal surfaces of the baffle unit 50 as exemplified by scattering source 52 in Fig. 1. The minimal blocking angle Q may be selected in accordance with a desired signal to noise ratio, and a maximal acceptable noise of the optical system 100. Typically, the minimal blocking angle Q may be selected in accordance with a desired system design.

[0061] To reduce reflection / scattering from internal surfaces of the baffle unit 50, Certain configurations of the baffle unit 50 utilize one or more vanes, or walls having a selected height and extending from internal surface of the baffle unit in a perpendicular direction with respect to the optical axis thereof. The vanes provide shading of internal surfaces of the baffle unit 50 and reduce collection of stray light 40.

[0062] Accordingly, the present disclosure provides an optical system, a corresponding baffle unit and a method for designing a baffle unit, blocking or at least significantly reducing stray light from entering the optical system. The baffle unit of the present disclosure is designed with at least one vane, and in some embodiments with two or more vanes, positioned and configured for shading of internal surfaces of the baffle unit and edges of the one or more vanes.

[0063] Figs. 2A and 2B exemplify the baffle 50 including a vane 54, Fig. 2A exemplifies a cut view of the optical system 100 and the baffle unit 50, and Fig. 2B shows a structure of the vane 54 from the point of view of the optical system 100. The baffle unit 50 may be configured as a cylindrical structure, or include a varying diameter as indicated above. The one or more vanes along the baffle unit 50 may be formed by rings, typically flat rings that are configured to block reflections from internal surfaces of the baffle. Fig. 2B exemplify a vane 54 including a vane surface (marked by 54) and an inner edge of the vane 540. The edge 540 of the vane 54 may add stray light collection in the form of a ring of light associated with light scattered from the edges 540 of the vane.

[0064] Generally, the baffle unit 50 and the optical system 100 are illustrated herein as having cylindrical symmetry. Accordingly, the illustrations in the figures represent a cross section of the cylindrical structure. In this connection Figs. 3A to 3F exemplify certain considerations in design of a baffle unit according to some embodiments of the present disclosure, and Fig. 4 illustrates a baffle unit according to some embodiments of the present disclosure.

[0065] Fig. 3A exemplifies an input aperture AB, e.g., being a lens diameter of an optical system 100, and the field of view (FOV) thereof. As indicated above, the illustration is a cross section of a cylindrical symmetry around an optical axis OA of the system. Locations C and D are selected at a distance from the input aperture AB. The selected distance is determined in accordance with system design parameters and preferences. Fig. 3B further illustrates an extreme path 40 of light at angle 0 with respect to the optical axis OA. Path 40 emerges from a selected location D, point E is determined at a location where path 40 crosses the FOV, defining a length of the baffle. In Fig. 3C the diameter of the baffle unit is determined. As shown, a line, stretches from A via D, and eventually intersect with a straight line extending from E and F and continues to define a location 53. position 53 is associated with a plane perpendicular to the optical axis and including points E and F. The location of the intersection 53 defines a minimal diameter of the baffler unit 50. Fig. 3D further illustrates inner vane wall 56 extending from the selected points C and D toward the external diameter of the baffle unit 50. Additionally, Fig. 3E adds the external surface 58 of the baffle unit 50 resulting in a defined structure of the baffle unit 50, including an external surface 58 and at least first and second vanes 54 and 56. Fig. 3F exemplifies the structure of the resulting baffle 50 unit.

[0066] As exemplified in Fig. 3F, and based on the design process described in Figs. 3A to 3E, the baffle unit 50 may include a cylindrical or cylindrical-like structure 58, and two (or more) vanes 54 and 56. The one or more vanes may include at least one inner vane 56 having position and height selected to block light arriving from an inner surface of the baffle unit 50 from arriving into the optical system, i.e. from entering input aperture AB. This configuration generally allows a single light ring associated with light scattered from edge of first vane 54, which is not specifically blocked. Generally, the edge of the inner vane 54 is completely block from illumination by the first vane 56.

[0067] In accordance with the design technique, it can be appreciated that dimensions of the baffle unit 50 may be selected in accordance with optical parameters of the associated optical system and one or more selection parameters, e.g., distance of inner vane 56 from lens of the optical system. Reference is made to Fig. 4 showing a calculated data on Length and Radius of the baffle unit according to some embodiments of the present disclosure for different selection of inner vane distance. The exemplary data shown in Fig- 4 is calculated for a certain selected minimal blocking angle 0=15 degrees. As shown, placing the inner vane 56 at a relatively short distance from input aperture / lens of the optical system results in a larger radius and a shorter baffle unit 50. This is while placing the inner vane at a larger distance enables reduced baffle diameter while requires a longer baffle unit. In general, various parameters such as the diameter and length of the baffle unit and the locations of the vane(s) may be selected and optimized in accordance with selected applications and desired dimensions of the baffle unit 50.

[0068] The baffle unit 50 may generally further include a connection port for attachment to an optical system, enabling the baffle to be selectively attached to the optical system, or detached therefrom. In some embodiments, the baffle 50 may be an integral part of the optical system, configured as a part of the optical systems body.

[0069] Further, Fig. 5A to 5F exemplify an additional configuration and design method of a baffle unit according to some embodiments of the present disclosure. Fig. 5A exemplifies an input aperture AB (or lens diameter) of the optical system, the field of view (FOV) for imaging, and an optical axis OA of the system. Section AB represents the aperture / lens diameter, and points C and D define selected points at edge of the field of view defined by certain angular range FOV. The distance between input aperture AB and points C and D is selected in accordance with a system design parameters and preferences. For example, a field of view may be 15 degrees, 10 degrees, 5 degrees, 1 degree, or any other selected angular range. Fig. 5B further illustrates stretching a line 40 defining the minimal blocking angle Q for blocking of stray light. More specifically, light arriving from sources with angle ( / .>() is blocked by the baffle unit and does not enter the optical system. The minimal blocking angle Q is defined with respect to the optical axis OA of the optical system. Line 40 is stretched from a selected location D being along the edge of the FOV at a selected distance from the lens aperture AB. In Fig. 5C two shading lines 42 are marked. The shading lines 42 extend between the edge of the lens diameter (point A) and the opposite selected point D (or B and C), marking points E and F at a location where line 42 crosses line 40 to define a length of the baffle unit at the crossing point with line 40. Fig. 5D further illustrates baffle unit 50, its internal surface 58 and vanes 54 and 56. The baffle unit 50 is formed by a cylindrical structure having a minimal diameter selected at least by the location of points E and F, such that the inner vane 56 blocks light scatter ed / reflected from the internal surfaces 58 and from edge ring of the first vane 54 of the baffle from entering into the optical system via aperture AB. Additionally, the edge of the baffle unit, or first vane 54 is positioned to block light arriving from outside the field of view (FOV) at angle a>0 from illuminating the edges of the inner vane 56, such that edge of the first vane 54 shades points C and D from stray light components. Fig. 5E illustrates two baffle configurations 50 and 50’ determined in accordance with the above-described technique as described with reference to Figs. 5A to 5D. Fig. 5E illustrates how baffle dimensions may vary in accordance with selection of points C, D, E and F for a given Field of view (FOV) and for a given minimal blocking angle 0. It can be appreciated that for larger baffle radius, the length of the baffle may be reduced for a given angular range FOV and a minimal blocking angle 0.

[0070] Further, it can be appreciated from Figs. 5A to 5E that the selection of the diameter of the baffle unit may determine higher of the first vane 54. In the example of Figs. 5A to 5E, the first vane 54 is formed by the structure of the main cylinder of the baffle unit 50. In some examples, the baffle unit may be configured with larger diameter, thus utilizing a first vane having a selected height.

[0071] Accordingly, Fig. 6 provides an exemplary illustration of baffle unit 50 according to some embodiments of the present disclosure. Baffle unit 50 is configured to be associated with an optical system having an input aperture IA and includes a generally cylindrical body and one or more vanes 54 and 56. Fig. 6 exemplifies a baffle unit 50 having two vanes 54 and 56 including a first vane 54 and a second (inner) vane 56. The dimensions and locations of the vanes and the diameter of baffle unit 50 are selected to provide shading of light components originating from sources at angles greater than a minimal blocking angle 0. More specifically, the baffle is configured to eliminate collection of light outside the field of view by an angle greater than a selected angle 0.

[0072] Accordingly, the inner vane 56 has height and location configured to prevent light scattered by inner surface 58 of the baffle unit 50 from entering the input aperture IA. This is exemplified by virtual line AE extending from an edge A of the input aperture toward the edge 540 of the first vane 54. Accordingly, the first vane 54 blocks light arriving with an angle a>9 from reaching the edge 560 of the inner vane 56, and inner vane 56 blocks light reflected / scattered from the inner surface 58 or the edge 540 of the first vane 54 from entering the input aperture IA of the optical system.

[0073] The baffle unit 50 may be formed of any selected materials including e.g., polymers, plastic, metal, ceramic, or any other material. Preferably, baffle 50, or at least inner surfaces 58 thereof may be painted with black paint having low reflection and / or high absorption characteristics.

[0074] Accordingly, the accurate dimensions of the baffle unit 50 may be determined in accordance with several requirements including angular range of FOV of the optical system, minimal blocking angle 0, and selection of distance of the inner vane 56 from the input aperture, or lens, of the optical system. In this connection Fig. 7 shows calculated data on the length and the radius of the baffle unit 50 in accordance with the distance of the inner vane (56) from the lens / input aperture of the optical system for a minimal blocking angle 0=15 degrees. As shown, differently than the configuration of Figs. 3A- 3F and Fig. 4 allowing one ring of light associated with edge of the first vane to be collected, the configuration of Fig. 5A-5E and Fig. 6 provides blocking of light scattered by all vane edges and inner surfaces of the baffle unit 50 from being collected by the optical system. Utilizing the suitable design described herein, the length and the minimal diameter of the baffle unit vary with the selected location of the inner vane 56. More specifically, for configurations where the inner vane 56 is placed in a close proximity, short distance, from the input aperture of the optical system, the length and the radius of the baffle unit may be large. Additionally, an increase in distance of the inner vane 56 and the lens of the optical system enables reducing the length and the radius (or diameter) of the baffle unit, up to a minimal length. Following the minimal length (ml), a further increase in distance between the inner vane and lens of the optical system results in further increase in baffle length, while the minimal diameter may remain similar.

[0075] A comparison between Figs. 4 and 7 shows that allowing light scattered / reflected from one ring, typically associated with the edges of the first vane 54 as exemplified in Figs. 3A to 3F enables to design smaller baffle unit, while the additional design requirements for blocking light scattered by the edge of the first vane as illustrated in Figs. 5A to 5D and Fig. 6, requires longer and larger baffle. Accordingly, the present disclosure provides a baffle unit, an optical system including a baffle unit and a method for design of a baffle unit, configured to eliminate, or at least significantly reduce collection of stray light arriving from an angle greater than a selected minimal blocking angle 0. The present disclosure utilizes optical design and selection of location and height of one or more vanes to determine the baffle unit structure.

[0076] It is to be noted that the various features described in the various embodiments can be combined according to all possible technical combinations.

[0077] It is to be understood that the invention is not limited in its application to the details set forth in the description contained herein or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Hence, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

[0078] As such, those skilled in the art will appreciate that the conception upon which this disclosure is based can readily be utilized as a basis for designing other structures, methods, and systems for carrying out the several purposes of the presently disclosed subject matter.

[0079] Those skilled in the art will readily appreciate that various modifications and changes can be applied to the embodiments of the invention as hereinbefore described without departing from its scope, defined in and by the appended claims.

Claims

CLAIMS:

1. A baffle unit for use in association with an optical system, the baffle comprises: a main body formed of a cylindrical member; a connection adaptor positioned at one end of the cylindrical member and configured for connecting to the optical system; and one or more vanes extending from an inner surface of the cylindrical member and configured to reduce stray light rays from entering the optical system; wherein at least height and location of the one or more vanes provide blocking of light components having an incident angle greater than a selected minimal incident angle Q and reflection thereof from the inner surface of the cylindrical member from entering the optical system; and wherein said one or more vanes further comprise at least a first vane being a frontmost vane of the baffle unit and at least one inner vane, location and height of the first vane being selected to block light components having an incident angle greater than the selected minimal incident angle Q from impinging on edges of the at least one inner vane.

2. The baffle unit of claim 1, wherein location and height of the at least one inner vane are further selected to block light components originating from edges of the first vane from entering the optical system.

3. The baffle unit of claim 1 or 2, wherein inner surfaces of the baffle unit and the one or more vanes are treated with low reflectivity / light absorbing material.

4. The baffle unit of any one of claims 1 to 3, wherein the connection adaptor is configured for selectively connecting the baffle unit to an optical system.

5. The baffle unit of any one of claims 1 to 4, wherein the connection adaptor is configured for permanently connecting the baffle unit to a selected optical system.

6. The baffle unit of any one of claims 1 to 5, wherein the cylindrical member is configured with diameter variation along optical axis thereof.

7. An optical system comprising at least one detector, a lens arrangement and a baffle unit positioned for limiting collection of stray light by the lens arrangement; the baffle unit comprises: a main body formed of a cylindrical member; and one or more vanes extending from internal surface of the cylindrical member and configured to reduce stray light rays from entering the optical system;wherein at least height and location of the one or more vanes provide blocking of light components having of an incident angle greater than a selected minimal incident angle 0 and reflection thereof from inner surface of the cylindrical member from entering the optical system; and wherein said one or more vanes comprise at least a first vane being a frontmost vane of the baffle unit and at least one inner vane, location and height of the first vane being selected to block light components having incident angle greater than a selected minimal incident angle 0 from impinging on edges of the at least one inner vane.

8. The optical system of claim 7, wherein the optical system is characterized by an angular span of field of view thereof being smaller that the selected minimal blocking angle 0.

9. The optical system of claim 7 or 8, wherein said one or more vanes comprise at least a first vane being the frontmost vane of the baffle unit and at least one inner vane, location and height of the at least one inner vane are selected to block light components originating from edges of the first vane from entering the optical system.

10. The optical system of any one of claims 7 to 9, configured for low light imaging.

11. The optical system of any one of claims 7 to 10, wherein inner surfaces of the cylindrical member and the one or more vanes are treated with low reflectivity / light absorbing material.

12. The optical system of any one of claims 7 to 11, wherein the cylindrical member is configured with diameter variation along optical axis thereof.

13. A method for designing a baffle unit, the method comprising:(a) determining a field of view angular range, a minimal blocking angle 0, and an input aperture of an associated optical system;(b) selecting a distance of an inner vane with respect to the input aperture of an optical system;(c) determining a length of the baffle unit in accordance with the minimal blocking angle 0 and location of the inner vane;(d) determining a minimal diameter of the baffle unit in accordance with shading line defined by location of the inner vane blocking light from entering the input aperture of an optical system;(e) defining a structure of the baffle unit in accordance with (a)-(d) and providing output data indicative thereof.

14. The method of claim 13, wherein said determining a length of the baffle unit comprises determining a length providing shading of an edge of the inner vane with respect to light components having an incident angle greater than the selected minimal blocking angle 0.

15. The method of claim 13 or 14, wherein said determining a minimal diameter of the baffle unit comprises determining the minimal diameter to provide shading of an internal surface of a body of the baffle unit by a first vane.

16. The method of any one of claims 13 to 15, wherein said determining a length of the baffle unit comprises determining a shading line resulting by edge of the inner vane with respect to the minimal blocking angle and input aperture of the optical system.

17. The method of claim 13, wherein said determining a length of the baffle unit comprises: determining a path of a first light ray passing through a location of an edge of the inner vane and reaching an opposite edge of the input aperture; and determining a length of the baffle unit in accordance with a location of intersection of said first light ray with a second light ray arriving an opposite edge of the inner vane and an angle associated with FOV angle with respect to an optical axis.

18. The method of claim 17, wherein determining a minimal diameter of the baffle unit comprises selecting a distance of the location of intersection from the optical axis.

19. The method of any one of claim 13 to 18, wherein selecting a distance of an inner vane with respect to the input aperture of an optical system comprises selecting a desired length and diameter / radius of the baffle unit.

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