CA2922442A1

CA2922442A1 - Optical arrangement for providing a 360° view

Info

Publication number: CA2922442A1
Application number: CA2922442A
Authority: CA
Inventors: Reinhold DE FRIES
Original assignee: FoxyLED GmbH
Current assignee: FoxyLED GmbH
Priority date: 2012-09-04
Filing date: 2013-09-04
Publication date: 2014-03-13
Also published as: KR20150054891A; EP3028101A1; DE102012215624B3; WO2014037371A1; CN104903791A

Abstract

The invention relates to an optical arrangement which can be used in particular as a 360° optical system for applications in which the use of a camera with a classic objective in the direct beam path is not possible. The invention proposes an optical arrangement which comprises at least one belt lens (1) and at least one optical sensor (2) that is at least partly arranged in the beam path of the at least one belt lens (1). In particular, optical signals pass through the belt lens without being reflected. Thus, a belt lens optical system suitable for a 360° view is provided in combination with a centrally arranged image sensor system, which can be used in order to reliably detect and analyze moving objects, preferably from a bird's-eye view. The belt lens optical system in combination with the image sensor system constitutes a 360° monitoring system which operates effectively and which can be integrated easily into technological processes. A preferred embodiment is characterized by a belt lens design with a fast lens speed and a central image sensor system for monitoring the surroundings with a movement analyzing function.

Description

The invention relates to an optical arrangement which can be used in particular as a 360 optical system for applications in which the use of a camera with a classic objective in the direct beam path is not possible.
Individual pivoting and/or movable cameras can be used for 3600 monitoring of the surroundings; or a plurality of cameras are located in such a way that all areas can be detected. In general, wide-angle cameras are used for this. However, the prior art includes known monitoring systems, with which 360 panoramic images can be taken indirectly by means of a camera. In this case, the camera is directed at a convex mirror which reflects distorted images of the surroundings onto the image plane of the camera via a further mirror. The distorted image data is then converted into rectified image data with an image analysis system.
Such an indirect optical monitoring system is described, for example, in DE

Al which focuses primarily on the monitoring of the internal space of a vehicle. Using at least one panorama camera images are generated in curvilinear coordinates, transformed to planar or cylindrical coordinates and then subjected to an electronic image evaluation. Persons and/or objects are detected with this such that an automatic adjustment of the seat or the safety devices can be carried out, for example, for each seating position. In the event of a car accident the extracted information should be stored and/or can be conveyed to a rescue center by radio. This system can also monitor parts of the exterior, so that it is also suitable as a collision warning or parking assistance system.
In order to fulfill the functional description explained above, the aim is to primarily use a conventional digital camera in combination with at least one mirror. Depending on the objective regarding which area is to be monitored, the location and orientation of the camera and the mirrors are to be redefined.
In the field of the invention, an arrangement for 360 reception and for focusing light signals is also known from patent specification DD 219 884 Al. In the case of this solution, light is directed by a mirrored belt lens onto a photodetector.
An optical instrument and a method for optical monitoring of the surroundings of slowly moving vehicles is known from the publication EP 2 433 837 Al. In the case of this

2 solution, light is directed by a mirrored belt lens onto an area detector in order to generate a first image, and light is directed via a combination of prisms and lenses onto the area detector in order to generate a second image.
A similar solution which can be used as a camera attachment is described in European patent specification EP 0103 301 B1.
A lantern for radiating a warning signal all around, wherein a belt optical system is used, is known from the utility model application DE 203 05 625 Ul.
The object of this invention is to provide an optical arrangement which avoids the disadvantages of the conventional solutions and which can be used in order to reliably detect and analyze moving objects, preferably from a bird's-eye view.
This object is achieved according to the invention by the features of Claim 1.
Expedient embodiments of the invention are set out in the dependent claims.
A particular advantage of the optical arrangement according to the invention is that monitoring of the surroundings is made possible, even in adverse lighting conditions.
This is achieved by using an optical arrangement which comprises at least one belt lens and at least one optical sensor. According to the invention at least one optical sensor is arranged directly and/or indirectly in the beam path of at least one of the belt lenses. It is understood that an arrangement directly in the beam path of the belt lens is an arrangement where no refractive and/or reflective elements such as additional lenses, prisms or mirrors are located in the beam path between the belt lens and the optical sensor. Accordingly, an arrangement indirectly in the beam path of the belt lens is understood to be an arrangement where the light coming from the belt lens is conducted by refractive and/or reflecting elements to the optical sensor, wherein said conducting can also include a reversal of the beam path.
According to the invention the belt lens is designed in such a way that no reversal of the beam path takes place inside the belt lens. In particular, optical signals or at least a portion of the optical signals pass through the belt lens without being reflected. The at least one belt lens and the at least one optical sensor are preferably arranged such that the optical signals or at least a portion of the optical signals travel from the entry into the at least one belt lens up to the at least one optical sensor without being reflected.
The result of this is that the optical signals are attenuated less than in the conventional

3 solutions.
The optical arrangement can be deemed to be a camera with a special objective.

According to the invention the special objective comprises at least one belt lens, wherein the at least one belt lens can be combined with one or more additional optical components. Such a combination of belt lens(es) and one or more optical components is referred to hereinafter as a belt lens optical system.
The belt lens or belt lens optical system is preferably a fast-speed belt lens or belt lens optical system.
The belt lens is in particular a substantially circular, transparent optical element. The cross-section of the belt lens preferably has two spherical sections in order to generate a lens effect. The belt lens preferably has a biconvex cross-section. In a preferred embodiment the belt lens is constructed from a plurality of optical elements which, together, form a substantially closed ring. In a further preferred embodiment the belt lens is designed as a Fresnel belt lens.
The optical sensor is preferably a photodiode array or a photodiode matrix, in particular a CCD sensor (CCD = Charge Coupled Device). Optical sensors which comprise organic semiconductor materials or which are made of organic semiconductor materials such as e.g. organic photo sensors or organic photodiodes, are preferably used.
It is advantageous if the optical sensor is configured as a curved sensor. In one preferred embodiment the optical sensor is designed as a cylinder or cylindrical casing.
The cylinder or cylindrical casing is aligned along the axial symmetry axis of the belt lens or belt lens optical system. The image of the surroundings is preferably displayed directly on the sensor, which is in the form of a cylinder or cylindrical casing, by the belt lens or the belt lens optical system. In other preferred embodiments additional optical elements are arranged in the beam path between the belt lens and the sensor in the form of a cylinder or cylindrical casing, for example in order to adjust the dimensions of the optical arrangement and the imaging properties of the belt lens or belt lens optical system to one another. It may prove to be advantageous, if the optical sensor forms at least a part of the surface of a cone. By varying the aperture angle of the cone, the beam path of the optical arrangement can be adjusted, for example, to the structure of the optical arrangement.

4 In another preferred embodiment the optical sensor is configured as a planar or flat sensor. The planar optical sensor can be part of a digital camera. The image information supplied by the belt lens or belt lens optical system is preferably displayed on the sensor via at least one optical element arranged in the beam path between the belt lens/belt lens optical system and the planar sensor. In a preferred embodiment the beam path is deflected by the at least one optical element inserted into the beam path.
In a preferred embodiment the optical element is a conical mirror which is aligned along the axial symmetry axis of the belt lens or belt lens optical system.
In a preferred embodiment a first portion of the optical signals travels from the entry into the at least one belt lens up to at least one first optical sensor without being reflected, while at least one optical element is arranged in the beam path of a second portion of the 'optical signals, which optical element displays the second portion of the optical signals on at least one second optical sensor.
In a further preferred embodiment a lens, preferably an annular lens, particularly preferably an annular lens with a zero meniscus cross-section is arranged in the beam path between the belt lens/belt lens optical system and the planar sensor next to the mirror, in order to adjust the image size of the image supplied by the belt lens/belt lens optical system and the conical mirror to the optical sensor.
In general, the optical elements arranged in the beam path between the belt lens/belt lens optical system and the optical sensor can be light-deflecting, light-reflecting and/or refractive elements.
Optical sensors with a low resolution can be used for the purpose of detecting moving objects.
In a preferred embodiment the optical arrangement comprises at least one energy source for supplying at least the optical sensor, at least one multiplexer connected to the optical sensor and at least one AD converter in order to digitize the analog data supplied by the multiplexer. The digital data can then be provided to a data processing unit.
In a preferred embodiment the optical arrangement further comprises at least one data processing unit such as e.g. at least one processor. The at least one data processing unit is at least temporarily connected to at least one part of the optical sensors, so that signals or data can be exchanged between the optical sensors and the at least one data processing unit.
In another preferred embodiment the optical arrangement further comprises at least

5 one light-emitting element such as, for example, at least one light-emitting diode (LED).
In another preferred embodiment at least one belt lens/belt lens optical system and at least one optical sensor are combined in a common structural unit. The common structural unit can, for example, be a housing, in particular a light, preferably a street light. In another preferred embodiment the common structural unit also comprises at least one data processing unit. Additionally or alternatively, one or more data processing units can also be provided, which are arranged outside the common structural unit, for example as a central control unit for a plurality of structural units.
In a preferred embodiment at least one part of the data processing units is configured such that the signals supplied by the optical sensors are analyzed in order to detect moving objects. In addition, in a preferred embodiment the light-emitting elements are controlled by at least one data processing unit. In a preferred embodiment at least a part of the light-emitting elements are controlled as a function of a moving object. In particular at least a part of the light-emitting elements is enabled or dimmed up, if an object moves in the area detected by the sensors. The controller can also be designed such that the light-emitting elements are disabled or dimmed down, if no moving object has been detected within a specified period.
In another preferred embodiment at least two, but preferably a plurality of, structural units are controlled by at least one data processing unit. It can be arranged such that multiple structural units communicate with one another, in order to announce, for example, an approaching object to another structural unit. In a preferred embodiment the movements of the object are analyzed, for this purpose, for example, by vector analysis, in particular by analyzing the optical flow.
It can also be the case that optical signals, in particular light signals from the visible and/or invisible frequency range are detected by the optical sensors of a structural unit and transmitted to other structural units. The signals can be passed on as optical signals. In this case, the signals detected by the optical sensor of a structural unit are transmitted to a data processing unit which is also encompassed by the structural unit or arranged separately from the structural unit. The data processing unit analyzes the

6 signals and activates the light-emitting element of the structural unit as a function of the result of the analysis, said light-emitting element emitting corresponding signals.
Alternatively or additionally, the optical signals received can also be forwarded by the data processing unit in other ways, for example by wire to a different data processing unit or by radio. The analysis of the optical signals by the data processing unit can comprise a decoding. Such optical arrangements can be used, for example, in submarines in order to transmit signals over water.
In a preferred embodiment the optical arrangement is equipped both with optical sensors and with light-emitting elements, so that the optical arrangement can be used both as a (3600) light receiver unit and as a (360 ) light transmitter unit.
In another preferred embodiment the optical arrangement is only operated as either a separate (360 ) light receiver unit or as a separate (360 ) light transmitter unit.
In a preferred embodiment at least one of the data processing units is configured to carry out at least - an analysis of signals detected by the at least one optical sensor, - a detection of moving objects, in particular a vector analysis, - an execution of image processing algorithms, in particular transforming signals detected by the at least one optical sensor, - a generation of signals which can be visualized by an optical output unit, in particular as a function of detected signals, - an activation and/or deactivation, in particular a dimming up and/or dimming down, of the at least one light-emitting element as a function of moving objects detected, - a control of a plurality of structural units, in particular as a function of moving objects detected, - a transmission of signals detected by the at least one optical sensor of a first structural unit to the at least one optical sensor at least one second structural unit and/or to a data processing unit.
In a preferred embodiment the belt lens and image sensor system are embedded in a common housing as a closed structural unit. The most compact design of the series is the symbol-providing functional unit having an image sensor, which is in the form of a cylinder or cylindrical casing and which is specially adapted to the characteristics of the lens. It can, for example, be used in a space-saving manner in street lights in order to activate the dimming up of LED light sources, on detecting approaching objects,

7 including in dimly-lit light conditions, and for receiving data via light signals. The multi-channel image sensor, which is connected to a constant current source and designed as a photodiode matrix, receives the analog image signals transmitted by the belt lens directly and forwards these to the analog multiplexers located in the central electronic control. The signals are digitized by means of an AD converter and transferred to the existing computer unit for further processing. A monitor can be connected via an interface for symbolized visualization of the movement processes of objects.
It is also possible to carry out a vector analysis of movements.
The term 'symbol-providing' denotes the fact that the image information received from an optical sensor, preferably following processing by software, as a coarse-resolution object image can be displayed on optical output devices, such as e.g. on a monitor. In a preferred embodiment detected objects are reproduced as geometric symbols, for example, as a flashing cross or the like.
According to a preferred embodiment of the image-providing function, the analog image data generated by a belt lens is deflected by means of a conical mirror in combination with an annular lens to a conventionally planar image sensor or digital camera, digitized there and then further processed and analyzed by the computer unit provided. The distorted images of the surroundings which are transformed into Cartesian coordinates can be visualized on a connected monitor in real time or on subsequent retrieval.
The application of the belt lens, reversing the direction of the beam path, constitutes another preferred embodiment. LED light sources are arranged around the center of the lens so that their beam angles run collinearly or parallel with the focal rays of the belt lens, which are generated by the latter's biconvex cross-section. The rays of light emerging from the outlet then generate a specified cone of light as required, for example, for the operation of street lighting.
In another preferred embodiment a 360 camera unit is provided for monitoring the surroundings via a belt lens/belt lens optical system, which sends the analog image information from its detection area in the direct beam path to a centrally arranged image sensor which is in the form of a cylinder or cylindrical casing, from which image sensor the analog data is then routed via multiplexers and AD converters to a separate computer unit for further processing. The belt lens/belt lens optical system and the image sensor with its connection leads for the constant current source and the outputs

8 identified according to the channel they belong to and PIN numbers, together with the housing, form a compact functional unit which is therefore also suitable for receiving and forwarding data via light signals.
In another preferred embodiment the analog image signals provided by the belt lens optical system are deflected by means of a conical surface mirror and, first of all, transmitted via an annular lens to an integrated area image sensor, from which the digitized data is then transferred by cable or radio to the separate computer unit for further processing. A separate digital camera can be mounted on the interface provided for it, dispensing with the area image sensor, for selected applications.
The invention thus provides a belt lens/belt lens optical system which has been developed for a 3600 view in combination with a centrally arranged image sensor system, which can be used in order to reliably detect and analyze moving objects, preferably from a bird's-eye view. The "optical axis" of the optical arrangement according to the invention thus preferably forms an angle with the axial symmetry axis of the belt lens, which angle deviates from the right angle. The conical casing is referred to as the "optical axis" of the optical arrangement according to the invention, which conical casing is created when the optical axis of a lens, which has the same cross-section as the belt lens, is rotated about the axial symmetry axis of the belt lens.
The angle enclosed by the "optical axis" of the belt lens with the axial symmetry axis is preferably approximately 300 to approximately 80 , particularly preferably approximately 400 to approximately 70 , very preferably approximately 60 . It is a 360 monitoring system which operates effectively and which can be integrated easily into technological processes. A preferred embodiment is characterized by a belt lens design with a fast lens speed and a central image sensor system for monitoring the surroundings with a movement analyzing function.
One embodiment of a 360 camera unit according to the invention is shown in the following drawings where:
Figure 1 shows a schematic cross-sectional view of a symbol-providing 360 camera unit through its housing and belt lens. The cylindrical body of the image sensor, with its photodiode arrangement which is embedded in the casing thereof can be observed as a complete view, Figure 2 shows a schematic cross-sectional view of an image-providing 360 camera

9 unit through the latter's housing, belt lens, conical surface mirror and annular lens for the analog output. The interface for the arrangement of an area image sensor 6 or a digital camera is shown.
The schematic representation of Figure 1 shows the components of a 3600 camera unit according to the invention arranged in the housing 3. Of note are first of all the geometry and optical parameters of the fast-speed belt lens 1 which is made of transparent material and has a biconvex cross-section for the effective transmission of moving images of the surroundings in the direct beam path to the centrally arranged image sensor 2 which is in the form of a cylindrical casing. This direct transmission of the analog image signals to the sensor prevents the losses which generally occur in the case of a deflection of the beam path into a different plane, therefore allowing it to be successfully used in poor light conditions as well.
The main application of this functional unit is the reliable detection of moving objects and the analysis of movements for controlling technological processes and for receiving data via light signals. The movement processes are visualized by the conversion of moving images of the surroundings into geometric symbols. The housing 3 is designed with the required degree of protection in accordance with the existing conditions of use.
The schematic representation of Figure 2 shows the components of a modified form of a 360 camera unit according to the invention arranged in the housing 3. With an unchanged belt lens 1, with respect to the functional unit described above, a deflection of the beam path is required. For this purpose, a conical surface mirror 4 is arranged in the center of the belt lens 1. The tatter's base body is made of plastic with a finely machined, highly reflective coated surface. The image size of the deflected analog image information is adjusted by an annular lens 5, which is made of transparent material with a zero meniscus cross-section, to the area image sensor 6 which is arranged inside the housing 3 or the digital camera mounted outside on an existing connecting device. Due to the suitability of this functional unit for the image-providing representation, it can be used both for reference image comparisons in technological processes and in the object safety area.
The invention is not limited in its embodiment to the preferred embodiment examples indicated above. Rather, a number of variants which make use of the arrangement according to the invention, even with fundamentally different designs, are conceivable.

List of reference numerals 1 Belt lens 2 Image sensor in the form of a cylindrical casing 5 3 Housing 4 Conical surface mirror 5 Annular lens 6 Planar area image sensor

Claims

1. An optical arrangement comprising:
- at least one belt lens (1) and - at least one optical sensor (2) that is at least partly arranged in the beam path of the at least one belt lens (1), characterized in that the belt lens is configured such that optical signals pass through the belt lens without being reflected.

2. The optical arrangement according to Claim 1, characterized in that the at least one optical sensor (2) comprises at least one optical sensor (2) which is substantially in the form of a cylinder or cylindrical casing.

3. The optical arrangement according to Claim 1 or 2, characterized in that at least one part of the at least one optical sensor (2) is arranged directly in the beam path of the at least one belt lens (1) and/or that at least one light-reflecting, light-deflecting and/or refractive element is arranged in the beam path between at least one part of the at least one belt lens (1) and at least one part of the at least one optical sensor (2).

4. The optical arrangement according to any one of the preceding claims, characterized in that the at least one optical sensor (2) comprises diodes, in particular photodiodes.

5. The optical arrangement according to any one of the preceding claims, characterized in that the optical arrangement comprises at least one light-emitting element, in particular at least one light-emitting diode.

6. The optical arrangement according to any one of the preceding claims, characterized in that the optical arrangement comprises at least one data processing unit, wherein at least one part of the optical sensor (2) and/or at least one part of the light-emitting elements is/are at least temporarily communicatively coupled to the at least one data processing unit.

7. The optical arrangement according to any one of the preceding claims, characterized in that at least one of the belt lenses (1) and at least one of the optical sensors (2) are arranged in a common structural unit.

8. The optical arrangement according to Claim 7, characterized in that the common structural unit comprises at least one data processing unit.

9. The optical arrangement according to Claim 7 or 8, characterized in that a plurality of structural units are communicatively coupled to one another via one of the data processing units.

10. The optical arrangement according to any one of Claims 6 to 9, characterized in that at least one of the data processing units is configured to carry out at least - an analysis of signals detected by the at least one optical sensor (2), - a detection of moving objects, in particular a vector analysis, - an execution of image processing algorithms, in particular transforming signals detected by the at least one optical sensor (2), - a generation of signals which can be visualized by an optical output unit, in particular as a function of detected signals, - an activation and/or deactivation, in particular a dimming up and/or dimming down, of the at least one light-emitting element as a function of moving objects detected, - a control of a plurality of structural units, in particular as a function of moving objects detected, - a transmission of signals detected by the at least one optical sensor (2) of a first structural unit to the at least one optical sensor (2) at least one second structural unit and/or to a data processing unit.