Patent Description:
The present invention relates generally to laser receivers, and more particularly, to laser receivers of the type utilized in a variety of worksite applications such as construction and/or agricultural applications.

Worksite preparation typically includes grading and excavating portions of the worksite to form desired slopes or footprints. Relative elevation measurement is a critical element in most construction and agricultural worksite applications and the use of laser receivers to facilitate elevation measurement in such applications is widespread. For example, laser receivers are commonly attached to construction equipment (e.g., dozers, scrapers, excavators, and the like) to improve grading and excavating accuracy.

With respect to laser detection, these laser receivers typically include multiple radiation or sensing arrays, which are spatially arranged in a vertical pattern and which respond to impingement by a radiation source such as a laser beam. To achieve high precision and <NUM> degree detection such lasers typically utilize three (<NUM>) or four (<NUM>) sensing arrays spaced at <NUM> degree or <NUM> degree intervals, as the case may be. Each array of the laser receiver requires multiple individual photo detectors and associated monitoring circuitry. These laser receivers achieve high accuracy levels but design requirements do increase the overall part count, mechanical and electrical complexity, and cost of such laser receivers, as well as, increasing the potential for decreased reliability given the increased part count and overall complexity.

<CIT> discloses a device and method for measuring <NUM> dimension posture of moving object. A device and method for measuring <NUM> dimension posture of moving object are provided. The device comprises a computing and processing unit, at least one receiver and at least one theodolite; the computing and processing unit and the theodolite are installed on the fixed ground; the receiver is installed on the moving object to be measured; the theodolite and the receiver are communicated with the computing and processing unit, and the theodolite is connected with the receiver via the laser optical path.

<CIT> discloses an electronic light detection circuit for detecting an intensity modulated light signal on a photosensitive element under backlight condition. The circuit comprises the photosensitive element, in particular as a light position detector for detecting a striking position of the light signal spot within a detection window, an amplifier with high input resistance connected to an output of the photosensitive element and a backlight suppression circuitry. The backlight suppression circuitry is connected to the output of the photosensitive element in parallel to the amplifier and comprises an electronic active resonator structure. The active resonator structure is designed in such a way to provide a load impedance to an output of the photosensitive element with a low load impedance for low frequencies for suppression of natural and artificial backlight-saturation of the photosensitive element and a high load impedance at the frequency of intensity modulation.

Therefore, a need exists for a laser receiver configuration that has a streamlined mechanical and electrical design, reduced cost, and increased reliability without sacrificing any precision or accuracy.

The invention provides a laser receiver according to claim <NUM>, a method according to claim <NUM>, and a non-transitory computer-readable medium according to claim <NUM>. In accordance with various embodiments, a vision laser receiver is disclosed having a light receptive surface with a fixed geometry such that laser light striking the sensing surface will illuminate a particular section of the sensing surface and be visible, observable and/or detectable. An image sensor configured internal will observe and detect the illumination of the light receptive surface manifesting as an arc with a fixed radius based on the fixed geometry of the light receptive surface and the precise elevation and/or tilt of the laser receiver will be determined from the illumination of the light receptive surface.

In accordance with an embodiment, a laser receiver is provided which comprises a housing and a light receptive surface configured therein having a fixed geometry and which is light receptive. As used herein with respect to the light receptive surface, the term "light receptive" will be understood to mean a surface that is receptive to an incoming light beam such that the light beam is visible, observable and/or detectable at or on the surface. For example, the light receptive surface can be in the shape of a cone, column, cylinder or other similar fixed, geometric shape. The geometry of the light receptive surface, together with the light receptivity of the surface, will facilitate the elevation determination in accordance with various embodiments as detailed further herein below. The laser receiver also has an image sensor, illustratively, a camera, charge-coupled device (CCD) or CMOS image sensor for observing and detecting an incoming radiation source (e.g., a laser beam) to the laser receiver and detecting a position on the light receptive surface which is impinged by the radiation source. The laser receiver further includes a processor (e.g., digital signal processor (DSP)) which is responsive to the impingement of the light receptive surface through the processing of data collected from the illuminated region of the light receptive surface and for determining the laser position (i.e., the elevation of the laser) therefrom. That is, in accordance with an embodiment, laser light striking the light receptive surface will illuminate a particular section of the light receptive surface which will be detected and observed by the image sensor and provided as input to the digital signal processor which will execute vision recognition steps to determine the position of the radiation strike on the illuminated light receptive surface and, in turn, determine the precise elevation of the laser.

In accordance with an embodiment, the laser receiver is further able to determine any tilt (i.e., the tilt angle) in the laser receiver. In accordance with this embodiment, given the fixed geometry of the light receptive surface and its associate mathematical characteristics, adjustments and compensations are made as a function of the angle of the plane on which the laser strikes the light receptive surface thereby allowing for the determination of the tilt angle.

The various embodiments disclosed herein are directed to either so-called "reflective" embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims in that the laser plane and associated observation and detecting of the laser beam striking the light receptive surface occurs on the outside (i.e., the exterior) of the light receptive surface, or so-called "transmissive" embodiments where the laser plane and associated observation and detecting of the laser beam striking the light receptive surface occurs on the inside (i.e., the interior) of the light receptive surface. Notwithstanding these somewhat different physical characteristics between the disclosed reflective embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims and transmissive embodiments it will be understood that the image processing (as detailed herein below) is the same for both embodiments.

These and other advantages of the embodiments will be apparent to those of ordinary skill in the art by reference to the following detailed description and the accompanying drawings.

In accordance with various embodiments, a vision laser receiver is disclosed having a light receptive surface such that laser light received at the light receptive surface will illuminate a particular section of the light receptive surface (i.e., will be visible, observable and/or detectable). Illustratively, the light receptive surface has a defined geometry and is light receptive. An image sensor will detect and observe the illumination of the light receptive surface and determine a precise position (e.g., vertical position) of such illuminated section on the light receptive surface. The elevation of the laser can then be determined from such detected position.

<FIG> shows an exploded view of a conventional laser receiver. As shown, laser receiver <NUM> is used in a variety of applications such as on construction or agricultural sites and is typically mounted on a machine (e.g., a dozer) for <NUM> degree receiving, or mounted on a surveying pole or carried by the housing for handheld applications. An example of one such commercially available laser receiver is the Topcon LS-B2 laser receiver (part of the LS Series machine mounted laser receivers) available from Topcon Corporation. Laser receiver <NUM> has a housing top <NUM>, housing base <NUM>, LED panel <NUM> and a mounting post <NUM>. Configured around mounting post <NUM> is a series of light sensors, in particular, individual light senor arrays <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> which are symmetrically placed in a circular fashion to enable <NUM> degree laser receiving of an incoming laser beam from a laser transmitter (or radiation source). As will be appreciated, and while not shown in <FIG>, each light sensing array will have multiple individual photo detectors and multiple circuit boards and connectors for the individual sensor arrays <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>. Laser receivers, such laser receiver <NUM>, deliver excellent precision and are widely used but their design requirements tend to increase factors such as part count, mechanical and electrical complexity, and cost.

<FIG> shows a fully assembled view of laser receiver <NUM> configured in accordance with an embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims. As shown, laser receiver <NUM> has a housing <NUM>, housing top <NUM>, housing base <NUM> and power and data connector <NUM> built into housing base <NUM>. Housing <NUM> is illustratively constructed to include a fully transparent portion to allow for the detection of laser light. In an alternative embodiment, the transparent housing may be dyed (e.g., red) to allow light of a desired wavelength to pass and block other wavelengths in a well-known fashion. In this way, the dyed transparent housing will eliminate the need for image sensor <NUM> to filter out any unwanted light. Configured within housing <NUM> is light receptive surface <NUM> having a fixed geometric shape and traversing substantially the entire length of housing <NUM>. Light receptive surface <NUM> is illustratively shown as having a cone shape in accordance with the embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims but it will be understood that other geometric shapes can be used including, but not limited to, cylinders, rectangles, spheres ellipsoids, or paraboloids. The main requirements for selecting the shape of light receptive surface <NUM> are directed to having a fixed geometric shape, light receptive qualities and size depending on the overall physical footprint desired for the receiver. The fixed geometry and light receptivity will allow for elevation and/or tilt determination as detailed herein below in accordance with various embodiments.

Laser receiver <NUM> is further configured to include image sensor <NUM>, illustratively, a camera, charge-coupled device (CCD) or CMOS image sensor for observing and detecting a source of incoming radiation (e.g., a laser beam) to laser receiver <NUM> and detecting impingement by the incoming radiation on light receptive surface <NUM>. Laser receiver <NUM> further includes processor <NUM> (e.g., digital signal processor (DSP)) which is responsive to the impingement and illumination of light receptive surface <NUM> and for analyzing the illumination to accurately determine the laser position (i.e., the elevation and tilt of the laser). Illustratively, image sensor <NUM> and processor <NUM> are mounted on circuit board <NUM> in a well-known fashion. As such, in accordance with an embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims, laser light will illuminate a particular section of light receptive surface <NUM> which will be detected and observed by image sensor <NUM> and provided as input to processor <NUM> which will execute well-known vision recognition steps to determine the position of the radiation strike on light receptive surface <NUM> and, in turn, determine the precise elevation of the laser. Further details of laser receiver <NUM> and the determination of laser elevation and/or tilt in accordance with various embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims will now be discussed.

<FIG> show an exploded view <NUM> of light receptive surface <NUM> and image sensor <NUM> of laser receiver <NUM> as shown in <FIG>. In <FIG>, laser plane <NUM> is shown which strikes light receptive surface <NUM> from a particular direction <NUM>. As will be understood, laser plane <NUM> is generated by a laser transmitter capable of generating visible laser light. Such laser transmitters are well-known and may be stationary or rotating lasers. For example, one such commercially available laser is the Topcon RL-H4C construction laser available from Topcon Corporation. The laser receiver of the various embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims described herein is capable of being utilized with any type of visible laser source. Laser plane <NUM> strikes light receptive surface <NUM> below centerline <NUM> thereby illuminating and forming intersection curve <NUM> on light receptive surface <NUM>, that is, the intersection of laser plane <NUM> with light receptive surface <NUM>.

For furthering the understanding of the present disclosure, <FIG>, <FIG> will be discussed together with the main difference in the described embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims being where (i.e., below or above) the laser plane strikes the respective light receptive surface. That is, in the <FIG> depiction laser plane <NUM> strikes light receptive surface <NUM> below centerline <NUM> thereby illuminating and forming intersection curve <NUM> on light receptive surface <NUM>, that is, the intersection of laser plane <NUM> with light receptive surface <NUM>. In the <FIG> depiction, laser plane <NUM> is projected on (or at) light receptive surface <NUM> from direction <NUM> and at a point above (see, directional arrows <NUM> and <NUM>, respectively, indicating above and below directions) centerline <NUM>.

As shown in the embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims of <FIG>, given the defined geometric shape and configuration of light receptive surface <NUM>, the illumination of light receptive surface <NUM> will result in a projection of intersection curve <NUM> in a defined manner as prescribed by the geometric shape of light receptive surface <NUM>, here, the shape of a cone. More particularly, laser light from laser plane <NUM> striking the cone shape of light receptive surface <NUM> will result in intersection curve <NUM> having an arc shape. In this embodiment, as shown, light receptive surface is a substantially vertical orientation (i.e., no tilt). That is, the illumination of light receptive surface <NUM>, having a cone shape, will manifest as an arc given this orientation. As such, in this embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims, light receptive surface <NUM> is analogous to a projection screen (e.g., in a movie theater) such that the light is projected on to the surface and is thereby detectable and observable, for example, by image sensor <NUM>. That is, light receptive surface <NUM> has a plurality of pixels <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> through <NUM>-N that are mathematically defined in a contiguous manner across light receptive surface <NUM> which are representative of the light projected onto the surface by laser plane <NUM>. To further the description and understanding of this feature, <FIG> shows a bottom view <NUM> (also designated as View B on <FIG>) of light receptive surface <NUM> which illustrates the arc shape of intersection curve <NUM> having radius Ri <NUM> (resulting from circular pattern <NUM> that is illuminated given that laser plane <NUM> strikes light receptive surface <NUM> in a parallel fashion to base <NUM> of light receptive surface <NUM>). As will be appreciated, the conical shape of light receptive surface presents certain characteristics that can be exploited in determining laser elevation in accordance with the embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims.

Similar to the above-described embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims, the embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims of <FIG> further illustrates the advantages of the disclosed vision laser receiver. In this embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims, laser plane <NUM> is projected on (or at) light receptive surface <NUM> from direction <NUM> and at a point above (see, directional arrows <NUM> and <NUM>, respectively, indicating above and below directions) centerline <NUM>. Again, given the defined geometric configuration of light receptive surface <NUM> the illumination of light receptive surface <NUM> will produce intersection curve <NUM> in a defined manner as prescribed by the geometric shape of light receptive surface <NUM>, here, the shape of a cone. More particularly, laser light from laser plane <NUM> striking the conical shape of light receptive surface <NUM> will result in intersection curve <NUM> having an arc shape. Again, light receptive surface <NUM> has a plurality of pixels <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> through <NUM>-N that are mathematically defined in contiguous manner across light receptive surface <NUM>. <FIG> shows bottom view <NUM> (designated as View B on <FIG>) of light receptive surface <NUM> which illustrates the arch (or conic) shape of intersection curve <NUM> having radius R<NUM> <NUM> (resulting from circular pattern <NUM> that is illuminated given that laser plane <NUM> strikes light receptive surface <NUM> in a parallel fashion to base <NUM> of light receptive surface <NUM>). As will appreciated from the discussion above, intersection curve <NUM> is of a larger radius than intersection curve <NUM> (see <FIG>) given the projected laser beam was in a region of light receptive surface <NUM> that lies above centerline <NUM>. This can also be determined by a comparison of radius R<NUM> <NUM> and radius Ri <NUM> (see, <FIG>), respectively.

That is, given the conical shape of light receptive surface <NUM> the intersection curves (e.g., intersection curve <NUM>) produced by a received laser beam (e.g., from laser plane <NUM>) will have known, quantifiable geometric and location characteristics that can be used, in conjunction with well-known vision algorithms or computer vision techniques, to determine elevation. For example, given that the light of the laser on the surface will be at a different brightness, in accordance with an embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims, an edge detection algorithm can be used to isolate the arc of the laser from the background. This will provide a group of pixels with corresponding x and y coordinates that represent the arc of the laser. Alternatively, an algorithm that finds the middle of the mass of the laser arc can be used to provide a more precise x and y coordinate representation of the arc. Once the x and y coordinates are known that describe the arc, this information can be combined with a knowledge of the shape that the laser is striking such that the radius of the arc (or focal points if elliptical in shape) can be determined. This information would allow one to determine the elevation and tilt of the laser including as further detailed herein below in <FIG> directed to an embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims involving tilt of the laser receiver. Laser light projected on light receptive surface <NUM> that is below centerline <NUM> (see, directional arrow <NUM>) will produce intersection curves having a smaller radius than that of laser light above centerline <NUM> (see, directional arrow <NUM>). As will be appreciated, radius Ri <NUM> of intersection curve <NUM> will be smaller than that of an intersection curve resulting from a laser light above centerline <NUM> as will be further illustrated herein below.

In accordance with the embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims shown, intersection curve <NUM> will be illuminated and detected by image sensor <NUM>. For ease of illustration, intersection curve <NUM> is shown encompassing three (<NUM>) pixels, namely pixels <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM>, but it will be understood that the intersection curve line will encompass pixels over the entire length of the illuminated light receptive array region, for example the entire arc of intersection curve <NUM>. Information about intersection curve <NUM> detected by image sensor <NUM> will be used as input to processor <NUM> (see, <FIG>) which will use well-known vision recognition operations to determine the position of the received laser beam on light receptive surface <NUM> and, in turn, determine the precise elevation of the laser.

As will be understood, given the fixed geometrical shape of light receptive surface <NUM>, the location of the plurality of pixels <NUM>-<NUM> through <NUM>-N can be determined in a fixed coordinate system to facilitate the determination of the location of the laser beam on light receptive surface <NUM> (i.e., how far up or down the incoming laser beam is on the light receptive surface) which, in turn, allows for the determination of the elevation itself. As will be understood, the production calibration of the laser receiver would consist of having a laser strike the light receptive surface at known elevations and having the image sensor store mathematical constants to adjust its interior arc fitting formulas so that the known arc matches the known elevation of the calibration laser strike. This could be done for several elevations along the length of the surface to accommodate for variances in assembly of the image sensor. Notability, no field calibration of the laser receiver is necessary in any of the embodiments herein but can be optionally utilized.

In accordance with the embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims shown in <FIG>, the illumination of intersection curve <NUM> will be observed and detected by image sensor <NUM>. For ease of illustration, intersection curve <NUM> is shown encompassing three (<NUM>) pixels, namely pixels <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM>, but it will be understood that the intersection curve line will encompass pixels over the entire length of the illuminated sensing array region, for example, the entire arc line of intersection curve <NUM>. As before, information about intersection curve <NUM> detected by image sensor <NUM> will be used as input to processor <NUM> (see, <FIG>) which will use well-known vision recognition operations, as detailed herein above, to determine the position of the received laser beam on light receptive surface <NUM> and, in turn, determine the precise elevation of the laser.

Advantageously, as detailed above, a laser receiver is realized that provides a streamlined mechanical and electrical design, reduced cost, and increased reliability without sacrificing any precision or accuracy.

In addition to determining the elevation of a laser, the tilt of the laser receiver can also be determined as shown in the further embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims of <FIG>. In this further embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims, exploded view <NUM> shows laser plane <NUM> is projected on (or at) light receptive surface <NUM> at a point above centerline <NUM> (see, directional arrows <NUM> and <NUM>, respectively indicating above and below directions). As shown, in this embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims the laser light from laser plane <NUM> is not parallel to base <NUM> of light receptive surface <NUM> thereby defining angle <NUM> in the received laser beam from laser plane <NUM> on light receptive surface <NUM>. Again, the defined geometric configuration of light receptive surface <NUM> the illumination of light receptive surface <NUM> will produce intersection curve <NUM> in a defined manner as prescribed by the geometric shape of light receptive surface <NUM>, here, a conical shape. More particularly, laser light from laser plane <NUM> striking the conical shape of light receptive surface <NUM> will result in intersection curve <NUM> having an elliptical shape. That is, the illumination of light receptive surface <NUM>, having a cone shape, will manifest as an ellipse due to the angle of the strike and the tilt of the laser receiver. This is different from the embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims described herein above (see, <FIG>, <FIG>) where the laser plane is parallel the base of light receptive surface <NUM> and renders a circular shape.

Advantageously, in addition to the elevation determination, in accordance with this further embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims, the tilt of the laser receiver is also determined utilizing circular pattern <NUM> as illuminated by laser plane <NUM>. As will be understood, the intersection of laser plane <NUM> with light receptive surface <NUM> is, in geometric terms, an intersection of a plane with a cone which results in an ellipse being transcribed along the cone by the plane. The resulting ellipse and its associated mathematical properties such as foci, vertices and eccentricity taken in combination with the known mathematical properties of the cone shape facilitates the determination of the angle at which the laser plane is with respect to the laser receiver in accordance with the above-described embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims.

Certain of the embodiments detailed herein may require certain alignment correction from time-to-time (see, e.g., <FIG> and <FIG>). As in those previous embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims, light receptive surface <NUM> has a plurality of pixels <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> through <NUM>-N that are contiguous across light receptive surface <NUM>. <FIG> shows bottom view <NUM> (designated as View B on <FIG>) of light receptive surface <NUM> which illustrates circular pattern <NUM> of intersection curve <NUM> having foci Fi <NUM>-<NUM> and foci F<NUM> <NUM>-<NUM> (resulting from circular pattern <NUM> that is illuminated given that laser plane <NUM> is received by light receptive surface <NUM> at an angle to base <NUM> of light receptive surface <NUM>).

In accordance with the embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims shown in <FIG>, the illumination of intersection curve <NUM> will be observed and detected by image sensor <NUM>. For ease of illustration, intersection curve <NUM> is shown encompassing three (<NUM>) pixels, namely pixels <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM>, but it will be understood that the intersection curve line will encompass pixels over the entire length of the illuminated light receptive array region, for example, the entire elliptical line of intersection curve <NUM>. As before, information from the illumination of intersection curve <NUM> detected by image sensor <NUM> will be used as input to processor <NUM> (see, <FIG>) which will use well-known vision recognition operations to determine the position of the radiation strike on light receptive surface <NUM> and, in turn, determine the precise elevation of the laser.

<FIG> shows a flowchart of illustrative operations <NUM> for determining elevation and tilt angle in accordance with an embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims. More particularly, step <NUM> details receiving a laser beam at a light receptive surface which illuminates a defined intersection curve in the light receptive surface whereby observing and detecting an illumination of the light receptive surface (step <NUM>) will identify the intersection curve. As noted herein, such detection can be in accordance with either of the reflective embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims or transmissive embodiments as disclosed herein. The light receptive surface is illustratively a cone shaped surface such as light receptive surface <NUM> as shown in <FIG>. As detailed above, this sensing can be accomplished using an image sensor in the same field of vision as the light receptive surface and that monitors the light receptive surface.

From the intersection curve illuminated in the light receptive surface, step <NUM> details determining an elevation of the laser from the illumination of the light receptive surface. As detailed above, the precise elevation of the laser is determined using well-known vision algorithms that will calculate a location of the received laser light on the light receptive surface and, in turn, calculate the elevation of the laser therefrom. In accordance with an alternative embodiment, if the laser tilt is required (step <NUM>) then determining a tilt of the laser receiver from the illumination of the light receptive surface (step <NUM>) is accomplished as detailed above with respect to the embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims of <FIG>.

<FIG> shows a diagrammatic view of user <NUM> operating within laser system <NUM> configured in accordance with an embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims. Illustratively, laser system <NUM> utilizes laser receiver <NUM> configured in accordance with the embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims of <FIG> and pointed at a desired target (e.g., target <NUM>) being measured. Alternatively, laser receiver <NUM>, as described herein below, can also be utilized in a similar fashion. In this embodiment including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims, transmitter <NUM> (e.g., a rotating laser) is transmitting laser plane <NUM> which will be received by laser receiver <NUM> to determine the precise elevation (E) <NUM> and tilt angle (A) <NUM> as detailed hereinabove. Of course, as will be appreciated, there are numerous applications and configurations for delivering the laser receiver and the elevation and tilt angle determination of the various embodiments. For example, user <NUM> may mount laser receiver <NUM> on a pole to increase stability when holding laser receiver <NUM> in the field (e.g., a construction site). Another alternative is to mount laser receiver <NUM> on a dozer or other construction vehicle, to name just a few. Advantageously, in accordance with various embodiments, a laser receiver configuration (and elevation and tilt determination methodology) is realized that has a streamlined mechanical and electrical design, reduced cost, and increased reliability without sacrificing any accuracy characteristics.

The above-detailed embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims are directed to reflective embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims in that the laser plane and associated observation and detecting of the laser beam striking the light receptive surface occurs on the outside (i.e., the exterior of) of the light receptive surface. For example, the outside of light receptive surface <NUM> of <FIG>. The discussion that follows next herein below will be directed to transmissive embodiments where the laser plane and associated observation and detecting of the laser beam striking the light receptive surface occurs on the inside (i.e., the interior of) of the light receptive surface. That is, the observation and the detection of the incoming laser strike is observed and detected from a position within (i.e., inside) the light reflective surface no matter the shape (e.g., cone, rectangle, etc.). Notwithstanding these somewhat different physical characteristics between the disclosed reflective embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims and transmissive embodiments it will be understood that the image processing (as detailed above) is the same for both embodiments. This will be highlighted further herein below in the description of the transmissive embodiments and as set forth in <FIG>.

<FIG> shows a cross section view <NUM> of fully assembled laser receiver <NUM>. As shown, laser receiver <NUM> includes housing <NUM> which is comprised of transparent housing <NUM>-<NUM> and non-transparent housing <NUM>-<NUM> where transparent housing <NUM>-<NUM> allows for the penetration and detection of laser light. As mentioned above, in an alternative embodiment, transparent housing <NUM>-<NUM> may be dyed to allow light of a desired wavelength to pass and block other wavelengths in a well-known fashion. In this way, the dyed transparent housing will eliminate the need for image sensor <NUM> (illustratively shown as being comprised by camera <NUM> and lens <NUM> in <FIG>) to filter out any unwanted light. In accordance with embodiment of <FIG>, image sensor <NUM> is located inside of the cone-shaped light receptive surface <NUM> and is directed towards mirror element <NUM> which is an annular element in-line with and near photodiode <NUM> (see also, e.g., <FIG>) Mirror element <NUM> and filter element <NUM> may be glued in place to the inside area of light receptive surface <NUM>, or in an alternative embodiment, may be molded. Alternatively, in accordance with an embodiment, filter element <NUM> may be removed entirely if no optical filtering is necessary.

In accordance with the embodiment shown, as laser light from laser plane <NUM> strikes light receptive surface <NUM>, image sensor <NUM> will observe and detect a position on light receptive surface that is impinged by the laser light (i.e., radiation source) by viewing mirror element <NUM> and the associated image thereupon. Laser receiver <NUM> also includes base <NUM>, image sensor housing <NUM>, mounting cap <NUM> and photodiode <NUM> having a pair of leads <NUM> extending through base <NUM> which includes, illustratively, a circuit board with at least a processor mounted thereon (e.g., processor <NUM> as shown in <FIG>). The operation and functionality of photodiode <NUM> is further detailed herein below.

To further facilitate the understanding of the configuration and operation of laser receiver <NUM>, <FIG> and <FIG> show different exploded views of laser receiver <NUM>. In particular, <FIG> shows exploded view <NUM>-<NUM> of laser receiver <NUM> from the perspective of the image sensor <NUM> end of laser receiver <NUM>, and <FIG> shows view <NUM>-<NUM> from the perspective of the photodiode <NUM> end of laser receiver <NUM>. Camera <NUM> may be a small, digital camera such as the Basler Ace USB3 1300x30 digital camera as commercially available from Basler AG, Ahrensburg, Germany. As shown in <FIG>, laser receiver <NUM> is configured with mounting cap <NUM> and image sensor housing <NUM> which provides a housing for camera <NUM> and lens <NUM>. Again, as shown in <FIG>, image sensor housing <NUM> is mounted to mounting cap <NUM> in such a way to position image sensor <NUM> within the inside area of image receptive surface <NUM> (illustratively, a cone shape) and pointing at mirror element <NUM> and filter element <NUM> which are each mounted respectively within the inside area of image receptive surface <NUM>. Image receptive surface <NUM> is affixed to the underside of image sensor housing <NUM> and within transparent housing <NUM>-<NUM>.

<FIG> shows exploded view <NUM>-<NUM> of laser receiver <NUM> from the perspective of the photodiode <NUM> end of laser receiver <NUM>. As shown, laser receiver <NUM> is configured with light receptive surface <NUM> which fits inside transparent housing <NUM>-<NUM>. In turn, in accordance with the embodiment shown in <FIG>, laser receiver <NUM> includes mirror element <NUM>, illustratively shown as an annular flat mirror, which allows for the present configuration of laser receiver <NUM> whereby image sensor <NUM> is configured within light receptive surface <NUM>. As such, as will be understood, mirror element <NUM> increases the focal length of camera <NUM> such that camera <NUM> can observe and detect, in the mirror element <NUM>, an incoming light beam to light receptive surface. In a further embodiment, mirror element <NUM> can be configured as a concave mirror to provide for a so-called "powered surface" for further enhancement of the observation taking place at the mirror element <NUM> by image sensor <NUM>.

Laser receiver <NUM>, in accordance with the embodiment shown in <FIG>, further comprises compound parabolic concentrator <NUM> configured in front of photodiode <NUM> having leads <NUM> which are mounted into base <NUM> which, illustratively, includes at least processor <NUM>. Such configuration allows for enhancing the synchronization between the incoming laser strike and triggering of the shutter of camera <NUM> in capturing the image in the annular mirror (i.e., mirror element <NUM>). That is, as will be readily understood, a certain level of ambient light surrounding laser receiver <NUM> (e.g. sunlight) that may penetrate transparent housing <NUM>-<NUM> substantially contemporaneously with the light beam from laser plane <NUM> may decrease the efficiency of capturing the laser strike in annular mirror <NUM> by camera <NUM>. As such, in accordance with the embodiment, concentrator <NUM> improves the light gathering capability of photo diode <NUM> which is essentially performing exposure management to minimize the exposure duration and synchronize the shutter of camera <NUM> with the incoming laser beam. So, photodiode <NUM> is detecting a flash of light (i.e., the incoming laser beam strike) and signaling camera <NUM> to open its shutter at a specific time in order to match the camera's open shutter with the laser strike.

Again, as detailed above, the embodiments of <FIG> are directed to transmissive embodiments where the laser plane and associated observation and detecting of the laser beam striking the light receptive surface occurs on the inside (i.e., the interior of) of the light receptive surface. To this end, <FIG> shows a fully assembled view <NUM>-<NUM> of laser receiver <NUM> in accordance with such transmissive embodiments. Notwithstanding the somewhat different physical characteristics between the disclosed reflective embodiments including an example of a reflective mode, wherein the reflective mode is not claimed according to the wording of the claims and transmissive embodiments it will be understood that the image processing (as detailed above) is the same for both embodiments.

<FIG> shows a photograph image <NUM> of a laser receiver configured in accordance with <FIG> incurring an actual laser beam strike. The photograph image <NUM> therefore shows the form of the laser strike. As shown in image <NUM>, the incoming laser beam has illuminated light receptive surface <NUM> to manifest intersection curve <NUM> as described hereinabove.

As detailed above, the various embodiments herein can be embodied in the form of methods and apparatuses for practicing those methods. The disclosed methods may be performed by a combination of hardware, software, firmware, middleware, and computer-readable medium (collectively "computer") installed in and/or communicatively connected to a user device. <FIG> is a high-level block diagram of an exemplary computer <NUM> that may be used for implementing a method for determining laser elevation and/or tilt in accordance with the various embodiments herein. Computer <NUM> comprises a processor <NUM> operatively coupled to a data storage device <NUM> and a memory <NUM>. Processor <NUM> controls the overall operation of computer <NUM> by executing computer program instructions that define such operations. Communications bus <NUM> facilitates the coupling and communication between the various components of computer <NUM>. The computer program instructions may be stored in data storage device <NUM>, or a non-transitory computer readable medium, and loaded into memory <NUM> when execution of the computer program instructions is desired. Thus, the steps of the disclosed method (see, e.g., <FIG> and the associated discussion herein above) can be defined by the computer program instructions stored in memory <NUM> and/or data storage device <NUM> and controlled by processor <NUM> executing the computer program instructions. For example, the computer program instructions can be implemented as computer executable code programmed by one skilled in the art to perform the illustrative operations defined by the disclosed method. Accordingly, by executing the computer program instructions, processor <NUM> executes an algorithm defined by the disclosed method. Computer <NUM> also includes one or more communication interfaces <NUM> for communicating with other devices via a network (e.g., a wireless communications network) or communications protocol (e.g., Bluetooth®). For example, such communication interfaces may be a receiver, transceiver or modem for exchanging wired or wireless communications in any number of well-known fashions. Computer <NUM> also includes one or more input/output devices <NUM> that enable user interaction with computer <NUM> (e.g., camera, display, keyboard, mouse, speakers, microphone, buttons, etc.).

Processor <NUM> may include both general and special purpose microprocessors, and may be the sole processor or one of multiple processors of computer <NUM>. Processor <NUM> may comprise one or more central processing units (CPUs), for example. Processor <NUM>, data storage device <NUM>, and/or memory <NUM> may include, be supplemented by, or incorporated in, one or more application-specific integrated circuits (ASICs) and/or one or more field programmable gate arrays (FPGAs).

Data storage device <NUM> and memory <NUM> each comprise a tangible non-transitory computer readable storage medium. Data storage device <NUM>, and memory <NUM>, may each include high-speed random access memory, such as dynamic random access memory (DRAM), static random access memory (SRAM), double data rate synchronous dynamic random access memory (DDR RAM), or other random access solid state memory devices, and may include non-volatile memory, such as one or more magnetic disk storage devices such as internal hard disks and removable disks, magnetooptical disk storage devices, optical disk storage devices, flash memory devices, semiconductor memory devices, such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), digital versatile disc read-only memory (DVD-ROM) disks, or other non-volatile solid state storage devices.

Input/output devices <NUM> may include peripherals, such as a camera, printer, scanner, display screen, etc. For example, input/output devices <NUM> may include a display device such as a cathode ray tube (CRT), plasma or liquid crystal display (LCD) monitor for displaying information to the user, a keyboard, and a pointing device such as a mouse or a trackball by which the user can provide input to computer <NUM>.

It should be noted that for clarity of explanation, the illustrative embodiments described herein may be presented as comprising individual functional blocks or combinations of functional blocks. The functions these blocks represent may be provided through the use of either dedicated or shared hardware, including, but not limited to, hardware capable of executing software. Illustrative embodiments may comprise digital signal processor ("DSP") hardware and/or software performing the operation described herein. Thus, for example, it will be appreciated by those skilled in the art that the block diagrams herein represent conceptual views of illustrative functions, operations and/or circuitry of the principles described in the various embodiments herein. Similarly, it will be appreciated that any flowcharts, flow diagrams, state transition diagrams, pseudo code, program code and the like represent various processes which may be substantially represented in a computer readable medium and so executed by a computer, machine or processor, whether or not such computer, machine or processor is explicitly shown. One skilled in the art will recognize that an implementation of an actual computer or computer system may have other structures and may contain other components as well, and that a high level representation of some of the components of such a computer is for illustrative purposes.

Claim 1:
A laser receiver comprising:
a light receptive surface (<NUM>) having a fixed geometry;
an image sensor (<NUM>) configured internal to the light receptive surface for detecting an illumination of the light receptive surface
characterized by the illumination of the light receptive surface manifesting as an arc with a fixed radius based on the fixed geometry of the light receptive surface; and
a processor (<NUM>) for determining an elevation using the illumination of the light receptive surface detected by the image sensor.