Safety housing for a wireless power supply

Abstract

A system for ensuring the integrity of the housing of a wireless power transmitter. The housing of the transmitter includes a window to allow a high-power light beam to leave the transmitter. The window is provided with an area that reflects at least a portion of the light beam and guides the reflected light beam onto a detector. Thus, the system can determine whether the window is undamaged because if the detector receives a satisfactory portion of the light beam, it indicates that the window is undamaged. This advantageously prevents damage caused by a dangerous light beam that may occur when the exit window of the transmitter is damaged. The laser beam is preferably circularly polarized before leaving the transmitter to prevent dangerous laser damage caused by reflection of the largest of the P or S polarization components, which may occur in the case of a linearly polarized light beam.

Description

Technical Field

[0001] The present invention relates to the field of wireless power beaming, and more particularly to a transmission system based on an application laser that ensures that the transmitter housing prevents unsafe beam exposure (even if the housing may be damaged) to beam optical power to a mobile electronic device in a home environment. Background Art

[0002] There has long been a need to safely transmit power to remote locations without physical wire connections. In the past few decades, with the popularity of battery-powered portable electronic devices and the recent proliferation of Internet of Things devices that need to be regularly recharged or continuously connected to a power source, this need has become important. Such mobile applications include mobile phones, laptops, cars, toys, wearable devices, and hearing aids. Currently, the capacity of existing technology batteries and the typical battery usage of heavily used smartphones may require the battery to be charged more than once a day, making the need for remote wireless battery recharging important.

[0003] Nearly a century after the invention of the battery, between 1870 and 1910, Tesla attempted to use electromagnetic waves for long-distance power transmission. Since then, many attempts have been made to safely transmit power to remote locations, which can be characterized by distances significantly greater than the transmitting or receiving devices. This range has been from NASA's SHARP (Stationary High Altitude Relay Platform) project in the 1980s to Marin Soljacic's experimental Tesla-like system in 2007.

[0004] Typical batteries for portable electronic devices have a capacity between 1 and 100 watt-hours and usually need to be charged daily, thus requiring higher power transfer over greater ranges.

[0005] Therefore, the need to safely transfer electrical power to portable electronic devices over ranges greater than a few meters has not been met.

[0006] One of the main obstacles to deploying wireless power infrastructure in a residential environment is safety, including safety in the event of an accident and / or when the equipment is used by an untrained person.

[0007] The currently allowed public exposure to the transmitted laser power levels is not sufficient to provide a useful amount of power without a complex safety system. For example, in the United States, Title 21, Volume 8 (21 CFR §8), Chapter I, Subchapter J, Part 1040 of the Federal Regulations, as amended in April 2014, addresses the performance standards for luminescent products (including laser products). For wavelengths outside the visible light range, there are Class I, III-b, and IV lasers (Classes II, IIa, and IIIa are for lasers between 400 nm and 710 nm, such as visible light lasers). Among lasers outside the visible light range, Class 1 is considered safe for general public use, while Classes IIIb and IV are considered unsafe.

[0008] Now refer to Figure 1 , which is a graph showing the MPE (Maximum Permissible Exposure value) for a 7 mm pupil diameter for Class I lasers according to 21 CFR §8 cited above for exposures from 0.1 - 60 seconds. As can be seen from the above figure:

[0009] (i) The maximum allowable exposure levels generally (but not always) increase with increasing wavelength, and

[0010] (ii) Even if the laser is turned off about 0.1 seconds after a person enters the beam, in order to meet the requirements specified in 21 CFR §8, no more than 1.25 W of light can be transmitted, and for wavelengths longer than 2.5 μm, at shorter wavelengths, the limits are several orders of magnitude smaller.

[0011] Therefore, without some sort of safety system, only a few milliwatts of laser power can be transmitted, and even if fully converted back to electrical energy, the power supplied by this laser power is much lower than the power required to charge most portable electronic devices. For example, a mobile phone requires 1 to 12 W to charge, depending on the model.

[0012] To transmit power above the Class I laser MPE, a safety system is required. Such a safety system, for example, is the safety system proposed in WO 2007 - 036937 titled "System for Wireless Power Supply" granted to Alpert et al., which discloses a system that protects a user from exposure when the user enters the beam.

[0013] However, the prior art does not address safety issues arising from misuse or system malfunction.

[0014] An object of the present invention is to provide a safety system that is resilient to misuse, malfunction, and other events in the system that may render the systems described in the prior art useless.

[0015] The entire disclosure of each publication mentioned in this section and other parts of the specification is incorporated herein by reference. Summary of the Invention

[0016] The present disclosure describes a system that remains safe even when the housing of a wireless power transmitter adapted to power a receiver located far from the transmitter is damaged.

[0017] The transmitter generally includes a laser for directing a laser beam towards the receiver for wireless charging. The transmitter generally includes a beam deflection unit that allows the laser beam to be aimed at a receiver located within the field of view of the transmitter.

[0018] The receiver generally includes a photovoltaic cell for converting the received laser beam into electrical energy, which can be used to supply energy to an electronic device.

[0019] The laser inside the transmitter housing generally emits a high-power beam and the laser emission inside the housing is generally not protected by the safety systems in prior art systems. Thus, if an object is inserted inside the transmitter, it may be exposed to dangerous laser power levels. To prevent objects from being exposed to the laser power inside the transmitter and to protect the transmitter itself, the transmitter is generally equipped with a protective housing.

[0020] The transmitter is generally hung from the ceiling or mounted on a wall in a position similar to a lighting fixture. During wireless power supply, the receiver is generally in the same room as the transmitter because the receiver should be within the field of view of the transmitter to receive wireless power. The transmitter uses the beam deflection unit to direct the beam towards the receiver such that the transmitter can direct the beam towards the receiver even if the receiver changes position.

[0021] The transmitter is generally installed in a house, office, commercial space, or industrial space where people who are generally not trained in operating the transmitter and are generally not protected against laser injury may pass through the area around the transmitter. In such a setup, a tall object (such as a ladder) or a flying object (such as a ball) may collide with the transmitter and thus damage the transmitter. Therefore, if an object hits the transmitter, the housing of the transmitter may be damaged, which may cause potentially dangerous laser emissions to become accessible or be released.

[0022] The housing of the transmitter generally has a window that can be made of a material such as glass or plastic and at least most of the window is transparent due to its overall transparency level or because individual portions of the window have different transparency levels. The window allows the laser beam to be transmitted from the protective housing towards the receiver. The window can transmit at least 85% of the beam. The window can include a protective layer, such as one provided by Corning Incorporated of Corning, New York to make the window more durable. However, even with such a durable window, and even if the window is partially or fully recessed within the housing, the window may still be prone to damage.

[0023] A damaged or broken housing window can pose a safety hazard, such as a laser beam escaping from the transmitter reaching dangerous levels. This is because if the window is damaged or broken, the percentage of the light beam absorbed or reflected by the window may be less than the expected level, thereby emitting a higher level of laser power than contemplated. Additionally, a broken window can cause the light beam to be deflected from its original intended position, causing the beam to shine on a surface that may cause damage rather than on a receiver that will safely absorb the beam.

[0024] Accordingly, an object of the present invention is to provide a system that remains safe even when the housing is damaged.

[0025] In one embodiment, the window of the protective housing transmits most of the light beam outside the transmitter and towards the receiver, thereby providing wireless power to the receiver. However, a small portion of the light beam is not directed to the receiver but is used to check the integrity of the transmitter housing. This small portion of the light beam is reflected by the window and detected by a detector. If the window of the transmitter is damaged or absent, no light beam will reach the detector, or the characteristics (such as power, polarization, shape, or other beam characteristics) of the light beam reaching the detector may deteriorate. Thus, if the detector does not detect a light beam, it may indicate that the enclosed window of the transmitter housing has been damaged because the absence of the partially reflective surface of the window prevents the light beam from being reflected back to the detector from the window. Alternatively, if a light beam with an unexpected beam quality reaches the detector, it may indicate that the window is damaged because a broken window may cause the reflected light beam to have an unanticipated beam quality. If the transmitter system detects damage to the enclosed window, the system can respond by modifying the power level of the light beam, typically by reducing the power of the light beam or completely terminating laser emission.

[0026] The window can have a small area that is dedicated to reflecting a portion of the light beam to verify the integrity of the window, and this area can be coated with a reflective coating or a partially reflective coating. The laser can be commanded to direct the light beam onto this small reflective area at a predetermined interval so that the detector can periodically monitor whether the amount of light beam it receives is satisfactory. When performing such a window integrity check, the system can modify the transmission parameters, such as reducing the power level of the light beam. Since a high-power light beam is typically used to transfer power to the receiver during wireless power transfer, if such a light beam were to be directed to a special area and partially or fully reflected to the detector, the detector could be damaged by the high power of the light beam. In addition, the area in the window for window break detection may be partially transparent, so a portion of the light beam used to check the window integrity may be transmitted through the window in an unsafe direction; therefore, it is preferable to use a low-power laser beam.

[0027] The special area of the window can be opaque, reflective, absorptive, or can otherwise prevent risks to the surrounding area. The system can cause the light beam to pass through this special area at a fast scanning speed and additionally or alternatively at a high power level. A beam attenuator, diffuser, or reflector can be positioned between the laser and the special area. This component should be positioned so that it does not interfere with the light beam traveling through other parts of the window for wireless power transfer.

[0028] Alternatively, instead of using a special area for window break detection, the entire enclosed window can be partially reflective so that any part or at least an important part of the enclosed window can be used to reflect a small portion of the light beam for checking the integrity of the window, as explained below.

[0029] In one exemplary configuration, the enclosed window has a spherical shape that is concave towards the inside of the housing, and the pivot of the beam deflector and the window break detector are positioned at conjugate object and image positions such that the light beam reflected by the spherical window is directed towards the inside of the transmitter and always reaches the window break detector at the image point of the beam deflection unit. In such an embodiment, the entire area or its important part can be used for window break detection, which can be found on the optical path of the main light beam. Alternatively, the enclosed window can be flat or nearly flat, so only a portion (usually less than 10% of the window area) can be used for window break detection.

[0030] In one exemplary embodiment, the transmitter is adapted to emit a light beam having elliptical or circular polarization. The laser initially emits a linearly polarized light beam, and a quarter-wave plate can be used to convert the linearly polarized light emitted by the laser into a light beam having elliptical polarization or preferably having circular polarization.

[0031] It may be advantageous to transmit an elliptically polarized light beam because, unlike using linearly polarized light, if the elliptically polarized light is to pass through a surface other than the receiver outside the transmitter, the circularly polarized laser beam will be reflected at the average reflectivity of the P and S components, while the linearly polarized laser can be reflected at the maximum value in either the P or S component. Therefore, compared with linearly polarized light, the maximum reflection generated by a transparent surface at an angle different from the Brewster angle is lower for circularly polarized light.

[0032] Therefore, since beam reflection may be harmful to the environment and since it is not known at what angle the beam emitted by the transmitter impinges on an "alien" transparent surface outside the transmitter, it may be advantageous to use circularly polarized light.

[0033] Typically, the system also includes a safety system that reduces the laser power or shuts down the laser when an object is detected between the transmitter and the receiver.

[0034] Such a safety system typically detects an object found between the transmitter and the receiver, but it is difficult to detect an alien object inside the transmitter and the prior art systems do not address this possibility.

[0035] Another object of the present invention is to provide a system and method for detecting damage to a housing, particularly to a fragile window that may enclose the laser and other components of the transmitter.

[0036] Another object of the present invention is to provide a system and method for detecting damage to an optical component (enclosing window), even if such a component may be contaminated, such as with dust and fingerprints.

[0037] Another object of the present invention is to provide a system having improved signal-background performance in a dirty environment.

[0038] The present invention discloses a detection system and / or a method of using and operating the detection system, the detection system being configured to detect damage to an external transparent enclosing window.

[0039] The present invention includes a laser, typically a diode laser adapted to generate a substantially collimated beam, because the diameter of the beam remains fairly constant throughout the operating distance of the system and only expands to a size larger than the typical receiver size, the typical receiver size being in a range greater than the maximum operating distance of the system, such that the beam remains fairly collimated within the operating range of the system.

[0040] If the window is broken or damaged, safety hazards may arise, such as an increase in output power or output from an apparent location or direction different from the planned one. If the laser emits a beam at an angle, the broken window may cause the beam to deviate from its expected angular position. Such a deviation of the beam can be dangerous because components of the safety system (such as the detector described above) may be configured and aligned to a different location, and if the safety system incorrectly protects a space other than the expected space, the system may become unsafe. The safety system is typically aligned with the beam, for example by using a deflection mirror of the transmitter to aim its detection direction. This collinearity is maintained as long as the window is not broken or moved. However, if the window is broken or otherwise altered, the detection system and the beam may become misaligned, and the safety system may not operate as expected.

[0041] The system should be configured to: in the case where the system (typically by using a detector) detects damage to the transmitter window, typically respond by using a controller to change the power level of the beam, typically by reducing the power level of the beam or by completely terminating the laser to change the power level of the beam.

[0042] Other parts of the housing are preferably not made of a fragile material and are thus not easily damaged. However, if the product design includes other fragile housing parts, the system may also include a detector for monitoring their status and responding to them when necessary.

[0043] The current system can be designed to remain safe even if such less fragile parts of the housing are damaged. To achieve this, the current system can also include any one of the following three components:

[0044] - A double housing, such as an inner housing protecting the components within the transmitter housing, which is designed to prevent access to dangerous internal components even when the outer housing is damaged.

[0045] - A reinforced housing, constructed to withstand impact damage and wear.

[0046] - An active protection part of the housing - such as that described above for the transmitter window.

[0047] The system of the present disclosure can emit a laser beam having elliptical polarization or substantially circular polarization. Lasers, which are typically diode lasers, are typically configured to emit linearly polarized beams, and a quarter-wave plate can be used to convert the linearly polarized beam emitted by the laser into elliptical polarization, typically approaching circular polarization. In alternative embodiments, as is known in the art, devices other than wave plates are used to achieve such modification of the beam, for example by using total internal reflection.

[0048] It may be advantageous to make the emitted light beam elliptically polarized because, unlike a linearly polarized laser, a transparent surface into which an elliptically polarized light beam is inserted cannot pass through the surface at the Brewster angle or at an angle close to the Brewster angle, while a linearly polarized laser can pass through a transparent object at the Brewster angle, making it difficult for a security system to detect the transparent surface.

[0049] In addition, if a laser beam is incident on a flat transparent surface at a large angle, a circularly polarized laser will be reflected at the average reflection of the P and S components, while a linearly polarized laser may be reflected at the maximum of the P or S component. Therefore, compared with polarized light, the maximum reflection generated by a transparent surface at an angle greater than the Brewster angle for circularly polarized light is lower.

[0050] For example, compared with only 8.9% of the power of circularly polarized light, if linearly polarized light is incident on a transparent surface with a refractive index of 1.5 at an incident angle of 60 degrees, 17.66% of the power can be reflected.

[0051] Since such reflections may be harmful to the environment and since it is not known at what angle the light beam emitted by the transmitter will be incident on an "alien" transparent surface, it may be advantageous to use circularly polarized light.

[0052] Depending on the embodiment, the present invention may use more than one mechanism to detect damage to the external window. Some such methods are now listed.

[0053] In one embodiment, a light source is used to direct light generally from inside the housing towards the transmitter window. A laser is typically used as the light source, but other light sources such as LEDs and laser diodes can also be used for this purpose. The front window typically has a slightly reflective coating, typically on the order of 0.05%-5%, to allow most of the light to pass through the window while a small reflection (typically less than 1%) returns inside the transmitter. In embodiments using additional light sources other than lasers, the reflectivity can be significantly higher, even above 90%. A detector is positioned to measure the reflection and thus detect the presence of the window. If the window is damaged or absent, or tilted at an unexpected angle, the detector may not detect the reflection or may detect a change in the reflection. The detector is typically connected to a controller that can be configured to switch the system to a secure state when window damage or a change in the window is detected.

[0054] In an exemplary embodiment, the laser used as the power beam also acts as the light source.

[0055] In addition, the detector can be placed in the return beam path of the laser such that the detector can detect the center point of the field of view of the return beam. In such a setup, the very center point of the window is typically the most protected.

[0056] In one embodiment, the front window is coated with a conductive coating, and the resistance or conductivity of the window is measured by a sensor to allow detection of a damaged window.

[0057] In yet another embodiment, the window is coated with a conductive coating, and the capacitance between the window and another plate is measured, where the other plate is preferably also conductive and transparent and is generally parallel to the window. If the window is damaged, the capacitance changes, and the system reacts as if the window were damaged.

[0058] In yet another embodiment, the power reaching the receiver is measured. When the power suddenly increases, typically after a brief interruption, the window of the transmitter may be damaged, and the system reacts as if the window were damaged.

[0059] In another specific embodiment, ultrasonic waves are used to detect the state of a closed window by transmitting acoustic waves from one side of the closed window to the other side of the closed window, or by transmitting waves from the front of the window of the transmitter housing to the back thereof, or by measuring the reflection of acoustic waves on the window.

[0060] In yet another specific embodiment, a light source, typically an LED diode, is adapted to illuminate the side of an external window, and the light is totally internally reflected inside the glass towards a detector. If the glass is damaged, the total internal reflection mechanism will terminate, and the signal detected by the detector will be affected, causing the system to react as if the window were damaged or broken.

[0061] Generally, the glass of the housing is selected such that its transmittance at the operating wavelength of the light beam is greater than 90%, or even greater than 95%.

[0062] When the detector for detecting a damaged window is located near the laser beam axis or is coupled outside the laser beam axis, the light beam should not be blocked. This is typically achieved by using a beam splitter to couple out the reflected light.

[0063] If the detector is placed between the laser and the quarter-wave plate, a polarizer can be used to couple out the signal reflected by the front window without significantly affecting the laser power transmitted from the transmitter housing.

[0064] The 1 / 4λ plate can be slightly tilted so that its surface does not reflect light back to the detector (or more specifically, the entrance pupil of the detector). Other components associated with the transmitter can also be slightly tilted to avoid such reflections. The purpose of the tilting is such that the detector for the damaged glass can detect a window that is not tilted at least at one point and does not receive a reflected signal from the internal components. If positioned orthogonally to the light beam, it will directly reflect light along the incident path, which may add to the light reflected from the front window and complicate the detection of the damaged window.

[0065] If a laser / power beam is used as a light source for front window detection, an area on the front window is typically reserved for such detection. Such an area may have a special coating for window breakage detection or may use the same coating as the rest of the window. In this case, the detector can be adapted to detect different power levels.

[0066] When power is transmitted through a typically very small area reserved for glass integrity detection, the transmission parameters (such as the power level transmitted to the receiver) are typically reduced by the system, or in some cases, the power is not transmitted through the special area of the window at all.

[0067] Although the power may not be transmitted through the special area at all or may be transmitted through the special area with reduced performance, the laser beam can be regularly aimed at or near this area to verify glass integrity.

[0068] This special area on the window is characterized in that it reflects a portion of the laser light incident thereon into the pupil of the detector while optionally allowing most of the light to pass through the window.

[0069] The detector can be positioned and configured such that, except when it receives reflections from protected parts of the system (such as from the window), it is shielded from the laser and does not receive the full power of the laser, or even most of the laser power.

[0070] A glass integrity detector typically has an entrance pupil. Light passes through the entrance pupil and reaches the detector. This light may be attenuated. Light that does not pass through the pupil is typically severely attenuated. The size and position of the detector pupil can be selected such that the area of the window used for window breakage detection can be minimized, thus allowing maximum power transmission to the receiver. This allows wireless power transmission to utilize the maximum percentage of the window surface, through the area of the window other than the dedicated area.

[0071] To achieve this, an optical projection, such as a possibly defocused image of the detector pupil on the window, should be similar to the beam diameter on the window.

[0072] A small physical aperture, such as a pinhole or iris, or another type of aperture, is typically placed at the pupil of the detector. The pupil can be created by the aperture or by a lens or other focusing element in the beam path. Such an aperture can be used to reduce the light reflected from the surfaces inside the transmitter, which makes accurate detection difficult. The detector can advantageously be enclosed or partially enclosed in a structure adapted to block extraneous light arriving from directions other than the window direction.

[0073] In an alternative embodiment, a virtual image of the detector pupil can be placed at a preferred location inside or slightly outside the operating distance of the transmitter, such as at the center of the working range, or at the edge of the working range, or at the preferred operating distance of the transmitter's operating range. In this case, the same detector can also be used to measure the signal from the receiver during periods when the beam is not aimed at a special area on the transmitter.

[0074] To couple the light from the optical output to the detector, a polarization beam splitter or a low-loss beam splitter can be advantageously used. The beam splitter should generally have a coupling towards the detector of less than 2% and a transmission or reflection of the power beam of greater than 95%. One way to achieve this configuration is to use a transparent plate, which can advantageously be flat and at an angle close to the Brewster angle, at the position where the beam is linearly polarized. This configuration allows for the effective transmission of the linearly polarized beam emitted by the laser, while the beam reflected from the window at the orthogonal polarization will be effectively reflected towards the detector.

[0075] The system is typically also equipped with a detector configured to measure the power of the laser beam, called a power monitor or detector. It is generally best to place the power monitor between the quarter-wave plate and the scanning mirror to avoid polarization dependence of the measured power.

[0076] A small fraction, typically less than 10%, 5%, or 1% of the laser beam power, can be coupled to the detector.

[0077] Placing the coupler of the power monitor between the wave plate and the scanning mirror allows the coupler to be polarization-independent, which improves the accuracy of power measurement, enables the detector to measure the power after any losses caused by other components (such as a glass-breaking detector and a wave plate), and makes the coupler small.

[0078] In one embodiment, the detector is positioned at the center of the coupled output beam, outside the main beam path. Alternatively, the detector does not need to be placed at the center of the beam. Additionally, the beam diameter can be selected to be of a length similar to the detector diameter.

[0079] In an exemplary embodiment, the coupled output beam is focused onto the detector to allow sampling of the entire beam profile using a small, low-cost, low-noise detector. This configuration may be less susceptible to changes in the beam shape.

[0080] In a third specific configuration, a diffuser is used to diffuse the coupled output beam onto the detector to allow sampling of the entire beam profile using a small, low-cost, low-noise detector. In this case, the detector itself can be placed outside the specular reflection / transmission direction of the diffuser to measure a signal independent of changes in the beam shape.

[0081] Typically, such a configuration requires enclosing the diffuser and the detector in a small housing to prevent other detectors in the system from being exposed to the light from the diffuser.

[0082] In a particular embodiment, at least two power monitors are used.

[0083] In a preferred setup, the laser is a diode laser having a fast axis and a slow axis. The fast axis has a wider divergence angle at the exit of the laser diode, generally greater than 30 degrees, and the slow axis has a smaller angle, generally less than 15 degrees.

[0084] The power monitor is placed outside the specular reflection / transmission direction of the diffuser and moved to the direction of the fast axis rather than the slow axis (the direction mirror-reflected by the optical system), which can reduce noise.

[0085] In other alternative configurations, a fluorescent plate is used to extract a small amount of power from the main beam without a coupler, and that amount of power is directed onto the power monitor.

[0086] In another configuration, a dot beam splitter is used to couple the output power.

[0087] In another configuration, the power monitor is attached to the laser itself, optionally in the same housing, to allow for low-cost integration of the two components.

[0088] The beam splitter of the power monitor can be placed between the scanning mirror and the quarter-wave plate or another elliptical beam generator.

[0089] In certain configurations, if two power monitors are used, it is preferred to use two beam splitters.

[0090] Couplers for monitoring parameters external to the transmitter and for breaking the window detector can also be placed in the beam path inside the transmitter. For example, for detecting a receiver or for detecting communication with the receiver, detecting a signal from the receiver, detecting an object between the transmitter and the receiver, or other measurements of an object between the transmitter and the receiver or near the beam. Such a coupler should couple light into a lens / mirror / focusing system pinhole / iris / aperture system, where the pinhole is positioned at the image point at a location within the operating range of the system; in more general notation, the pinhole is positioned at a distance from the focus of the focusing system and between distances.

[0091] For example, if the focal length of the lens is f and the maximum operating distance is 10 m, the pinhole should typically be positioned at a distance of .

[0092] Thus, according to an exemplary embodiment of the device described in the present disclosure, a wireless power transfer system is provided, which includes a transmitter and a receiver.

[0093] The transmitter includes:

[0094] (i) A laser suitable for emitting a light beam.

[0095] (ii) A power monitor configured to provide an indication of the optical power of the light beam.

[0096] (iii) An outer housing including an optical window configured to transmit the light beam out of the outer housing.

[0097] (iv) An inner housing within the outer housing, including:

[0098] The laser,

[0099] The power monitor, and

[0100] A light beam blocking portion, which is at least one of the following: (a) opaque, (b) partially transmissive with an optical density of at least 0.5, or (c) diffusive. The light beam blocking portion is configured to: in the case where the light beam or the reflection caused by an object inserted into the light beam is guided onto the light beam blocking portion, absorb or diffuse at least part of the light beam, or at least part of the light beam reflection.

[0101] (v) A light beam deflection unit, and

[0102] (vi) A control unit configured to control the laser.

[0103] Wherein, the system further includes a detection unit configured to provide an indication of damage to the optical window of the outer housing, and the control unit is configured to respond to the indication by causing a modification of the system configuration.

[0104] The light beam blocking portion may be part or all of the wall of the inner housing. Generally, at least its main part has light beam blocking characteristics, which are at least one of the following: (a) opaque, (b) partially transmissive with an optical density of at least 0.5, or (c) diffusive. The light beam blocking portion of the wall is configured to: in the case where a part of the light beam or the light beam reflection caused by an object inserted into the light beam is guided onto the light beam blocking portion of the wall, substantially absorb or diffuse at least part of the light beam, or at least part of the light beam reflection, such that the part of the light beam or the reflection does not leave the outer housing through the optical window. The light beam blocking characteristics of the inner housing are thus operable to prevent part of the light beam or part of the light beam reflection from an object inserted into the light beam from leaving the outer housing in a manner other than through the window.

[0105] In such a wireless power transfer system, a modification of the system configuration can be a modification of the laser beam.

[0106] In addition, such a system can also include a collimator configured to cause the beam to diverge by no more than 5 degrees within the operating range of the transmitter, and the collimator is positioned inside the inner housing.

[0107] In addition, in any such wireless power transfer system, the window of the outer housing can have a transmittance of at least 90%. Similarly, the window of the inner housing can have a transmittance of at least 90%.

[0108] In any such wireless power transfer system, the beam deflector can be inside the inner housing.

[0109] According to another exemplary embodiment of the present disclosure, a wireless power transfer system is provided, which includes a transmitter and a receiver. The transmitter includes:

[0110] (i) A laser suitable for emitting a beam with power,

[0111] (ii) A collimator,

[0112] (iii) A polarization element configured to manipulate the polarization state of the beam, and

[0113] (iv) A controller suitable for controlling the power of the laser beam,

[0114] wherein the receiver has a maximum acceptance angle θ of the beam, and

[0115] wherein the polarization element is configured such that the polarization state of the beam leaving the transmitter is elliptical, and the elliptically polarized beam includes two phase-shifted linear components having a power ratio μ greater than 1 between the larger component and the smaller component, and a phase shift between the two linear polarizations, and

[0116] wherein the laser power is controlled such that the power P of the beam emitted by the laser is less than watts.

[0117] Another embodiment of such a wireless power transmitter can include:

[0118] (i) A laser suitable for emitting a substantially collimated laser beam,

[0119] (ii) An external output window suitable for transmitting the laser beam,

[0120] (iii) A beam deflection unit suitable for deflecting the laser beam through the external output window in any one of a plurality of directions, and

[0121] (iv) A detector having a pupil,

[0122] wherein

[0123] the external output window has at least one area adapted to reflect a portion of the laser beam towards the pupil of the detector, and

[0124] when the laser is not aimed at the at least one area, the detector is protected from the laser.

[0125] In such a wireless power transmitter, the system may further include a power monitor configured to detect at least a portion of the light beam and thereby indicate the power of the light beam. Additionally, such a wireless power transmitter system may include at least two power monitors. In yet another embodiment, the laser may include a first light beam power mode having a power less than a second light beam power mode. In the latter case, the transmitter may be configured such that at least one of the laser operation modes cannot be turned on when the light beam impinges on the at least one area. In such a case, the light beam deflection unit is adapted to direct the laser beam to the at least one area before the laser switches between the two operation modes.

[0126] According to yet another exemplary embodiment of the wireless power transmitter described above, the light beam deflection unit may be adapted to direct the laser beam to the at least one area during the system startup process. Additionally, the power of the laser beam before scanning the at least one special area should be lower than the power of the laser beam after scanning the at least one special area.

[0127] In any such wireless power transmitter, the at least one area may reflect less than 5% of the light beam. Additionally, the transmitter may include at least one optical element adapted to change the polarization of the emitted light beam. Additionally, the laser may emit a linearly polarized light beam, while the light beam passing through the window may be an elliptically polarized light beam or a circularly polarized light beam.

[0128] In any of these cases, the optical element may be aligned at a small angle with respect to the normal of the light beam. In this case, the alignment of the optical element should cause a reflection outside the pupil of the detector.

[0129] There is also disclosed a wireless optical power transmission system, comprising:

[0130] (i) a laser adapted to emit a light beam,

[0131] (ii) a housing for accommodating the laser, comprising:

[0132] (a) a light beam blocking portion, and

[0133] (b) A housing window for transmitting a light beam, the window including a predefined portion adapted to reflect at least a part of the light beam onto a detection unit.

[0134] (iii) A scanning mirror adapted to direct the light beam, and

[0135] (iv) A control unit adapted to receive signals from the detection unit and determine at least one light beam characteristic.

[0136] Wherein, when the light beam is directed onto the predefined window portion, the control unit is adapted to use the output of the detection unit to evaluate the integrity of the window and control at least one of the following: (i) the laser and (ii) the corresponding system configuration.

[0137] In such a wireless power system, the housing may further include an inner housing adapted to accommodate at least a part of the laser. In this case, the window for transmitting the light beam may be common to the outer housing and the inner housing. Alternatively, the inner housing may include a second window for transmitting the light beam to the housing window. In any of those embodiments, the inner housing may include a light beam blocking portion.

[0138] According to yet another embodiment of such a wireless power system, the window may be spherical, recessed into the transmitter, and the pivot of the scanning mirror and the detection unit are positioned at conjugate object and image positions such that for a certain angular range of the scanning mirror, the light beam reflected by the spherical window always reaches the detection unit.

[0139] Finally, any of these wireless power systems may further include at least one power monitor adapted to detect the power level of the emitted laser beam. In this case, the power monitor may include a diffuser and at least one detector such that the detector receives the spatially dispersed light beam. Description of the Drawings

[0140] The present invention will be more fully understood and appreciated in conjunction with the following detailed description, taken in conjunction with the accompanying drawings, in which:

[0141] Figure 1 Shows the published maximum allowable exposure converted to watts on a 7 - millimeter pupil for different exposure times according to US 21 CFR §1040;

[0142] Figure 2A Shows a typical residential environment where a wireless power transmitter mounted on the ceiling can be used to charge the batteries of various portable electronic devices;

[0143] Figure 2B Shows an exemplary embodiment of a transmitter having an inner housing that houses a laser and an outer housing that can house other components of the transmitter;

[0144] Figure 3A and Figure 3B shows an exemplary embodiment of a system for detecting the integrity of a window of an outer housing as shown in Figure 2B . Figure 3A shows an embodiment using two separate windows for the inner and outer housings, while Figure 3B shows an embodiment using a common window for the inner and outer housings;

[0145] Figure 4 shows an alternative exemplary system for detecting the integrity of an outer window of a transmitter housing by detecting a light beam transmitted through the window using a detector disposed outside the transmitter.

[0146] Figure 5 shows an alternative system for determining the integrity of an outer window by applying a conductive coating thereto, the resistance of which changes if the window is damaged;

[0147] Figure 6 shows an alternative system for determining the integrity of an outer window of a transmitter housing by using total internal reflection of light through a mirror;

[0148] Figure 7 shows an embodiment in which the window is partially reflective and has a spherical shape such that the integrity of the window can be determined for any angle of beam scanning;

[0149] Figure 8A and Figure 8B shows two alternative exemplary systems in which a specific portion of a window having predetermined reflection characteristics is used to monitor the integrity of the window;

[0150] Figure 9A and Figure 9B shows alternative exemplary embodiments for reducing the effect of external illumination on the sensitivity of the detection system, which ensures that only light from the returned beam is focused onto the detector so that the detector can more accurately determine the state of the outer window; and

[0151] Figure 10 shows another exemplary embodiment of a power monitor for determining the power of a light beam emitted by a laser and thereby determining whether the light beam inside and outside the outer housing is at a safe level. DETAILED DESCRIPTION

[0152] Now refer to Figure 1 , which shows the published maximum allowable exposure converted to watts on a 7 - millimeter pupil for different exposure times in accordance with US 21 CFR§1040.

[0153] Figure 2A A typical residential setup is shown where a wireless power transmitter 204 mounted on the ceiling can be used to charge various devices such as a laptop computer 207a, a tablet computer 207b, and a phone 207c. It should be understood that the transmitter can charge only one device at a time or may have the ability to charge more than one device simultaneously.

[0154] Now referring to Figure 2B , which shows an exemplary embodiment of the transmitter having an inner housing 203 that houses the laser 205 or at least the beam exit aperture of the laser, and an outer housing 204 that can house other components of the transmitter.

[0155] The advantage of the outer housing 204 is to protect the internal structure of the transmitter from damage, such as from impacts to the transmitter. Additionally, it protects the user from potential hazards, such as electrical, mechanical, thermal, or laser hazards that can occur if the electrical and laser components are not properly enclosed and not inaccessible.

[0156] The outer housing 204 is equipped with an emission window 201 that allows the laser beam 200 to leave the transmitter towards the receiver 207 or multiple receivers. In addition to the window 201, the housing 204 is typically made of an opaque and durable material, such as metal or a durable plastic or rubber, to prevent the laser beam from passing through the walls of the housing. The window 201 is typically the only part of the housing that allows the laser beam to pass through and is therefore typically made of glass or a durable plastic.

[0157] Due to the possibility of breakage of the outer housing 204, especially the emission window 201, the outer housing 204 should be equipped with means for a shut-off system, such as a shut-off switch or a detachable power cable. The laser and other sensitive components should additionally be partially or fully enclosed within the inner housing 203 so as to provide protection for the user even if the outer housing 204 is damaged, such that the laser is always inaccessible.

[0158] In the case of damage to the outer housing 204, the inner housing 203 also protects the laser from damage. Additionally, the inner housing 203 acts as a dust protection means for the internal components of the transmitter 200. The inner housing 203 is also equipped with a window 202 to allow the beam 200 to leave the inner housing.

[0159] The inner housing 203 can additionally house:

[0160] (i) A power monitor 206, which Figure 10is further shown in. The power monitor determines whether the level of the beam emitted by the laser is safe and acceptable. The inner housing 203 may not accommodate the entire power monitor. However, the inner housing 203 at least accommodates the input aperture of the power monitor.

[0161] (ii) A beam splitter 202 for coupling and outputting a portion of the beam to the power monitor 206, which may also act as the output window 202 of the inner housing, as shown in FIG. 3.

[0162] Generally, at least the laser and the power monitor 206, as well as other monitoring devices that the system may employ, are accommodated within the inner housing. In the case of a pulsed laser, the laser and the power monitor 206 measure the power or energy per pulse of the laser beam. The power monitor is accommodated within the inner housing because interference or damage to the power monitor may cause the system to become unsafe. For example, if the system is configured to use the measured power level to determine the power of the beam emitted by the laser, an incorrect output measurement by the power monitor may cause the system to emit a beam with a dangerously high power level. In addition, the safety system may be configured to use the power monitor to determine the portion of the beam absorbed by the receiver. This can be achieved by using the power monitor to determine the difference between the power level of the emitted beam and the power level reaching the receiver. If this difference is below a predetermined level, this indicates safe operation because no substantial power loss has occurred between the transmitter and the receiver. Therefore, it is very important to protect the power monitor and provide an accurate reading.

[0163] Other components may be external to the inner housing. For example, the electronic parts of the laser (such as the anode and cathode) may be located outside the protective inner housing, while the beam exit must be inside the inner housing. Similarly, the optical aperture of the power monitor must be completely enclosed within the protective inner housing. If an optical coupler is used to transmit / reflect a low percentage of the beam to the power monitor while reflecting / transmitting another portion outside the inner protective housing, only one side of the optical coupler needs to be inside the inner protective housing, i.e., the optical coupler may be provided on the wall of the inner housing.

[0164] The non-transparent portion of the inner housing should be constructed to be able to block the beam in the case where the beam is deflected from its designated path, for example, due to mechanical shock or due to a reflective component moving away from its intended safe position. These components should be designed to be able to block the beam for a sufficient length of time to allow the system power to be turned off, which may take up to 10 seconds or longer. Therefore, the non-transparent portions are generally made of materials that do not transmit the beam. Instead, they should be made of materials designed to absorb the beam or at least diffuse the beam. In addition, such materials should not melt when irradiated by the beam for a short period of time (usually at least 1 - 2 minutes), for example, to provide the user with sufficient time to respond and turn off the laser.

[0165] The transmitter is usually mounted on the ceiling, difficult to access, and may be directly connected to the main power supply. Therefore, to allow the user to turn off the system, there may be an external off-switch, which can usually be found on the external housing or via a remote control device or application. Alternatively, the system can be connected to the power supply via a plug that allows disconnection.

[0166] Other components that can be located inside the internal protective housing include a collimation system, a beam sampler, and a beam deflection device.

[0167] Contamination of the power monitor by dust can cause the safety system to incorrectly evaluate the level of laser power emitted by the system, usually resulting in the system underestimating the power, which can lead to unsafe operation of the system.

[0168] Therefore, the internal protective housing should be dust-proof to some extent to prevent dust from contaminating the laser and the power monitor. However, minor contamination during the product life cycle is usually acceptable.

[0169] Now refer to Figure 3A and Figure 3B , which illustrate exemplary embodiments of a system for detecting the integrity of the window of the external housing.

[0170] Figure 3A and Figure 3B schematically illustrate a system in which a small amount of light reflected from the window of the external housing is detected by a detector to evaluate whether the portion of the laser beam reflected from the window represents an undamaged window. If the detected beam level is lower than expected, which may indicate window damage or absence, the system can reduce the level of the laser beam or completely stop the laser from emitting the beam.

[0171] Now refer to Figure 3A . The internal housing 311 includes a laser unit 301 that typically has a diode laser emitter 302 and a collimation system 313 for generating a collimated laser beam. The laser beam is directed towards a beam splitter 304, where the beam splitter 304 typically directs less than 10% of the beam towards the power monitor 303 and allows the rest to pass through. The power monitor 303 determines whether the laser emits the beam at a safe and acceptable level.

[0172] The beam then impinges on a scanning mirror 305, which deflects the beam towards the window 306 of the internal housing and the window 307 of the external housing. Figure 3A The windows 306 and 307 in Figure 3B are shown as separate windows. However, the system can include a common window for the internal and external housings, as shown in

[0173] The window of the outer housing 307 can advantageously transmit most of the light beam outside the transmitter, such that most of the light beam of the laser reaches the receiver, as shown by the light beam illuminating the receiver 308. On the other hand, typically a small portion of the light beam is reflected from the window 307 towards the detector 309, which is a window integrity detector for determining the state of the outer window.

[0174] If the window is damaged or absent, no light beam will reach the detector 309, or the characteristics of the light beam (such as power, polarization, shape, or other light beam characteristics) may deteriorate.

[0175] The detector 309 can determine various characteristics of the light beam it receives and transmit the level or characteristics of the detected laser beam to the controller 310. Alternatively, if there is an indication that the window 307 is damaged or absent, the detector 309 can send a signal to the controller 310. In the case where the controller 310 does receive such a signal, or alternatively, if the controller 310 determines that the light beam level reaching the detector 309 is not the level of the expected light beam, the controller 310 sends a signal to the laser 301, instructing it to modify the power of the light beam or completely terminate the light beam to prevent damage caused by the laser, as if the window of the outer housing it indicates is damaged or broken.

[0176] The controller 310 can process the input and output signals of the entire system. For example, it can control the power monitor, the movement of the scanning mirror, and the laser power adjustment.

[0177] Now referring to Figure 4 , Figure 4 FIG. shows an alternative exemplary system for detecting the integrity of the outer window of a transmitter by detecting the properties of the light beam emitted through the window using a detector disposed outside the transmitter.

[0178] When the light beam passes through the window 402, if the two faces of the window are parallel, the light beam is offset from its original linear path to a path parallel to the original light beam 401. The confinement of the light beam is marked as 403. If the window is damaged and thus not in the path of the light beam, the light beam will not be refracted by the window 402, and the light beam confinement will be defined by the confinement 404 instead of 403. Additionally, there will be no power loss caused by the light beam passing through the window. As a result, the light beam marked by the confinement 404 will not only be in an unexpected position but also have a power higher than expected.

[0179] A safety system for measuring the integrity of the window 402 can be implemented using a detector (shown as detector 400), which can detect the characteristics of the light beam, such as the position, direction, or power of the light beam 401, and then the system can use these characteristics as a basis for determining whether the window 402 is intact.

[0180] Referring now to Figure 5 , Figure 5 which shows an alternative system for determining the integrity of an external window 502 by coating the external window with a conductive coating and thus forming a circuit, and measuring, for example, the current transmitted through the external window.

[0181] The window 502 is coated with a conductive coating 503 which has a resistance 503 across the window. A resistor 504 is connected in series with the conductive coating and the circuit is closed using a power supply 501 (which typically provides a low voltage DC), and an electrical characteristic such as voltage is measured by a voltmeter 505 typically across the resistor 504. If the window 502 is breached, the conductive coating 503 will not conduct electricity, the circuit will open, and the voltage across the resistor 504 will change, typically decreasing.

[0182] Other circuits can also be designed to achieve the same result, including measuring the capacitance between electrodes on opposite surfaces of the window.

[0183] Referring now to Figure 6 , Figure 6 which shows an alternative system for determining the integrity of an external window of a transmitter by using total internal reflection. The window 601 has a refractive index n such that it reflects light incident on its surface at an angle greater than sin -1 (1 / n). An LED 602 illuminates the window from one end and a detector 603 is positioned such that it can detect light totally internally reflected through the window 601. If the window 601 is breached, the portion of the light received at the detector 603 will decrease significantly.

[0184] Referring now to Figure 7 , Figure 7 which shows another embodiment where the entire window of the transmitter is partially reflective such that any part or at least most of the enclosed window can be used to reflect a small portion of the light beam for checking the integrity of the window.

[0185] This embodiment is different from the previously shown embodiments in that the transmitter window 702 has a spherical shape, recessed into the interior of the housing, and the pivot of the beam deflector 703 and the window integrity detector 700 are positioned at conjugate object and image positions such that despite the scanning movement of the scanning mirror 703, the light beam 701b reflected back into the housing by the spherical window 702 always impinges on the window integrity detector 700 located at the image point of the beam deflector unit 703. In such an embodiment, the entire area or most of it can be used for breach window detection. Thus, the light beam 701a used for wireless charging can be used to ensure the integrity of the window and a laser beam does not need to be regularly directed to any specific area of the window for breach window detection.

[0186] It should be understood that Figures 5 - 7 any window system described herein can be used for the external window of the transmitter to allow the light beam to leave the transmitter towards the receiver, or can be used as the window of the inner housing to enclose the laser and other sensitive components, or both. Monitoring for damage may be required for either of these two windows. In an arrangement where the inner housing and the outer housing share a window, the system as described above can be used for the shared window.

[0187] Now referring to Figure 8A and Figure 8B , Figure 8A and Figure 8B show another exemplary system where a specific portion of the window is used to monitor the integrity of the window.

[0188] Although the scanning mirror 801 generally rotates to direct the light beam to the transmitters and receivers that may be located around the room at regular intervals, the scanning mirror 801 is positioned such that it directs the light beam 800a to a specific portion of the window 802a, as Figure 8B shown, in order to test the integrity of the enclosure window 802 of the laser.

[0189] The specific window region 802a can be coated with a special reflective coating to more effectively reflect the light beam towards the detector.

[0190] The specific window region 802a is the region of the window where the light beam 800a impinges on the window at normal incidence, thereby directing a portion of the light beam directly back to the scanning mirror 801. The specific window region 802a represents the state of the enclosure window of the laser as a whole. A difference in the amount of light beam power from the window region 802a compared to the amount of light beam power normally expected from an undamaged window will indicate a problem with the window 802: if no portion of the light beam is reflected back to the scanning mirror, the window may be damaged, and if the amount of reflected light beam is less than expected, the window may be damaged or dirty. When any reflection of the light beam in the specific window region 802a reaches the scanning mirror 801, the specific window region 802a as shown in FIG. 8 is used.

[0191] Therefore, the light beam level reaching the detector 803 provides an indication of the window state.

[0192] Figure 8B shows an alternative way of positioning the detector 803 such that the light beam is reflected directly towards the detector 803 instead of being returned via the scanning mirror 801 as Figure 8A shown.

[0193] When the scanning mirror 801 is positioned at a specific angle, the light beam 800a irradiates on the window area 802a, and the window area 802a can be coated with a reflective coating to better reflect the light beam. This allows the detector 803 to detect the laser beam reflected away from the window area in the presence of the window, and determine how much light beam is reflected away from the window area 802a, thereby providing an indication of the status of the external window 802 of the transmitter.

[0194] The scanning mirror can direct the light beam onto the window area 802a at regular intervals so that the light reflected away from the window can be detected, thereby ensuring the integrity of the window 802.

[0195] Figure 8A An advantageous system for circularly polarizing the light beam 800a before it leaves the laser housing is also shown. Once the light beam leaves the transmitter and passes through the window 802, it can be reflected by objects in the room, which may potentially cause dangerous and uncontrollable damage caused by the light beam. When a linearly polarized light beam is reflected by a surface, the reflection of different components of the light beam may be stronger than that of an unpolarized or other polarized light beam, thereby increasing the level of the light beam that can be reflected around the room.

[0196] Figure 8A An advantageous system is shown in which the linearly polarized light beam 800a emitted by the laser 804 is circularly polarized by a quarter-wave plate 806 before leaving the enclosed window 802 of the laser.

[0197] The quarter-wave plate 806 is shown slightly tilted to advantageously prevent any part of the light beam from being directly reflected back to the laser 804.

[0198] Figure 8A A system is shown in which the laser 804 emits a light beam linearly polarized in one direction, such that it advantageously travels straight through the polarization beam splitter 805 without any light beam being reflected, thereby reducing light beam loss.

[0199] However, when the light beam returns from the window 802, the light beam first travels through the quarter-wave plate 806, which linearly polarizes the light beam in the vertical direction, such that when the light beam travels through the polarization beam splitter 805, most or all of the light beam is reflected at a right angle, thereby reaching the detector 803 instead of the laser. The returning light beam may damage the laser or cause the laser to emit a dangerous level of light beam.

[0200] Therefore, as shown in FIG. 8, the exemplary system advantageously uses a linearly polarized light beam when traveling through the polarization beam splitter 805, and uses a circularly polarized light beam when the light beam leaves the transmitter and travels around the room, which is accompanied by advantages.

[0201] Now refer toFigure 9A and Figure 9B which shows an exemplary embodiment for reducing the effect of extraneous illumination on the sensitivity of a detector system. The beam 900a returning from the window is reflected by a polarization beam splitter 905 towards a lens 907. The lens 907 focuses the beam 900b through an aperture 908 towards the detector 903 such that the aperture 908 only allows the light focused by the lens 901 to pass through and blocks any light from any other direction.

[0202] The system thus ensures that only the light from the returning beam is focused towards the detector 903, thereby ensuring that the detector accurately receives and measures the amount of light in the beam reflected from the window region 802a and does not receive illumination from light sources other than the returning beam 900a, such that the detector can more accurately determine the state of the external window.

[0203] Now referring to Figure 9B which shows a Brewster plate 909 in place of Figure 9A the polarization beam splitter shown in

[0204] Now referring to Figure 10 which shows an exemplary embodiment of a power monitor 1010 for determining the power of the beam emitted by a laser and thereby determining whether the beam is at a safe level inside and outside the outer housing.

[0205] Although most of the beam emitted by the laser 1000 travels towards the scanning mirror 1005 through the beam splitter 1004 and exits through the window 1006 of the outer housing of the laser towards a receiver (not shown), in order to measure the level of the beam emitted by the laser, a small portion of the beam is coupled out through the beam splitter 1004 towards the power monitor 1010. Thus, the portion of the beam reaching the power monitor represents the entire beam emitted by the laser.

[0206] A diffuser 1003 is used within the power monitor 1010 to average out any spatial structure in the portion of the beam reaching the detector such that the beam reaches the detectors 1001 and 1002 as a more uniform illumination. For redundancy, Figure 10 two detectors are advantageously shown in

[0207] such that the measurements from the detectors are compared so that any inconsistencies can indicate that one or both of the detectors have failed.

[0208] As Figure 10 The system shown as 1010 in Figure 10 uses a diffuser to average any spatial structure of the portions of the light beam arriving at the detector, or uses more than one detector as redundancy. This system can be similarly implemented in a break window detector to ensure that the break window detector gives an accurate representation of the light beam reflected from the window of the outer housing.

[0209] Those skilled in the art will appreciate that the present invention is not limited to what has been specifically shown and described above. Instead, the scope of the present invention includes combinations and sub - combinations of the various features described above, as well as variations and modifications that occur to those skilled in the art upon reading the above description and that are not in the prior art.

Claims

1. A wireless power transfer system, comprising a transmitter and a receiver, The transmitter comprises: (i) a laser suitable for emitting a laser beam; (ii) a power monitor configured to provide an indication of the optical power of the beam; (iii) an outer housing including an optical window configured to transmit the beam outside the outer housing; (iv) an inner housing within the outer housing, the inner housing including: the laser; the power monitor; and an inner wall, at least a major portion of which has beam-blocking characteristics and is at least one of the following: (a) opaque, (b) partially transmissive with an optical density of at least 0.5, or (c) diffusive, the beam-blocking portion of the wall being configured to: substantially absorb or diffuse the portion of the beam or the reflection of the beam caused by an object inserted into the beam when at least a portion of the beam or the reflection of the beam is guided to the beam-blocking portion of the wall, such that no portion of the beam or the reflection of the beam can be guided out of the housing except through the optical window; (v) a beam deflector unit; and (vi) a control unit configured to control the laser, wherein the system further includes a detection unit configured to provide an indication of damage to the optical window of the outer housing by reflecting the beam from the window and determining the presence of the reflection of the beam in the window, and the control unit is configured to respond to the indication by causing a modification of the configuration of the system.

2. The wireless power transfer system according to claim 1, wherein the modification of the configuration of the system includes a modification of the laser beam.

3. The wireless power transfer system according to any one of claims 1 and 2, further comprising a collimator configured to cause the beam to diverge by no more than 5 degrees within the operating range of the transmitter, the collimator being positioned inside the inner housing.

4. The wireless power transfer system according to any one of claims 1 and 2, wherein the window of the outer housing has a transmittance of at least 90%.

5. The wireless power transfer system according to any one of claims 1 and 2, wherein the window of the inner housing has a transmittance of at least 90%.

6. The wireless power transfer system according to any one of claims 1 and 2, wherein the beam deflector is inside the inner housing.

7. A wireless optical power transfer system, comprising: (i) a laser suitable for emitting a beam; (ii) a housing for accommodating the laser, the housing including: (a) a beam-blocking portion; and (b) a housing window for transmitting the beam, the window including a predefined portion suitable for reflecting at least a portion of the beam onto a detection unit; (iii) a scanning mirror suitable for guiding the beam; and (iv) a control unit suitable for receiving a signal from the detection unit and determining at least one beam characteristic, Wherein, when the light beam is guided onto the predefined window portion, the control unit is adapted to use the output of the detection unit to evaluate the integrity of the window and control at least one of the following: (i) the laser and (ii) the configuration of the system.

8. The wireless optical power transmission system according to claim 7, wherein, the housing further includes an inner housing adapted to accommodate at least a portion of the laser.

9. The wireless optical power transmission system according to claim 8, wherein, the window for transmitting the light beam is shared by the outer housing including the housing window and the inner housing.

10. The wireless optical power transmission system according to claim 8, wherein, the inner housing includes a second window for transmitting the light beam to the housing window.

11. The wireless optical power transmission system according to any one of claims 8 to 10, wherein, the inner housing includes the light beam blocking portion.

12. The wireless optical power transmission system according to claim 7, wherein, the window is spherical, recessed inwardly towards the interior of the transmitter including the laser, and the pivot of the scanning mirror and the detection unit are positioned at conjugate object and image positions such that for the angular range of the scanning mirror, the light beam reflected by the spherical window always reaches the detection unit.

13. The wireless optical power transmission system according to any one of claims 7 to 10, further comprising at least one power monitor adapted to detect the power level of the emitted laser beam.

14. The wireless optical power transmission system according to claim 13, wherein, the power monitor includes a diffuser and at least one detector such that the detector receives a spatially dispersed light beam.

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