EP1851583A2 - Audience scanning light projector and associated methods - Google Patents
Audience scanning light projector and associated methodsInfo
- Publication number
- EP1851583A2 EP1851583A2 EP05826155A EP05826155A EP1851583A2 EP 1851583 A2 EP1851583 A2 EP 1851583A2 EP 05826155 A EP05826155 A EP 05826155A EP 05826155 A EP05826155 A EP 05826155A EP 1851583 A2 EP1851583 A2 EP 1851583A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- power
- region
- data elements
- beam power
- spatial coordinates
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
- H04N9/3129—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] scanning a light beam on the display screen
Definitions
- the present invention relates to the field of laser projectors and, more particularly, to a laser projector for projecting patterns and arrays of beams directly into an audience for entertainment display purposes
- Projectors for laser display can generally be categorized into one of three groups: graphics projectors, beam projectors, and audience scanning projectors.
- Graphics projectors are those which project logos, text and other figures onto some projection surface such as a screen.
- these projectors employ an X-Y scanning system, usually consisting of two small mirrors mounted on galvanometer scanners. One mirror scans the beam in one linear direction (for example, horizontally) onto the second mirror, which scans the beam in the perpendicular direction (for example, vertically).
- the combined X-Y motion is normally used to draw outline-type vector images, using a point-by-point "connect the dots" method, according to software commands effected by a programmable controller operably connected with the laser projector.
- the audience views these figures on the screen in the same way that an audience would view a movie being projected onto a screen.
- a beam projector produces beams of light that are projected into mid-air.
- the beams are viewable in mid-air by virtue of fog, dust and moisture that either exists in the air or which is created by the performer or venue.
- the beams are often animated to produce a dynamic effect.
- the beams can be moved and animated in a number of ways.
- an X-Y scanning system is also used.
- the scanning system may be identical to that of graphics projectors (the projector is merely aimed into the air instead of at a screen), or the scanning system may scan more slowly than that of graphics projectors (since complex images may not be required).
- Use of an X-Y scanning system allows flexibility to create both simple placement of the beam to hit target mirrors or objects and also to allow more complex patterns such as circles and shapes to be projected.
- the generated light typically a laser beam
- the light merely travels from the projector to its destination surface, or along an uninterrupted path in mid air.
- Audience scanning projectors typically combine features of both graphics and beam projectors. Audience scanning projectors use X-Y scanners to project geometric figures, patterns and arrays of light beams directly into a viewing audience. As with beam projectors, when the laser is projected toward an audience, its beam also illuminates any fog, dust, and moisture in the air. The beams create dancing sculptures that are very pleasing to audience members and the beam comes in direct contact with the audience. The effect generated creates the illusion of being surrounded by a tunnel of light and by other geometric shapes that are formed by the light. One viewer has compared it to being inside a fireworks display, or at the bottom of a swimming pool filled with light. A typical audience scanning projector, as known in the art, is shown in Figure 4.
- the X-Y signals and beam power level signals are generated by a programmable controller which generally comprises a personal computer having suitable interface hardware, and running software for generating the images, patterns and shapes.
- the hardware generally includes an interface circuit board that connects to the computer. This interface circuit board includes digital-to-analog converters and voltage amplifiers, so that signals can be produced which correspond to X-Y beam positions, and to beam power levels.
- the X-Y beam positions and beam power levels produced by the interface hardware are sometimes referred to as "command signals," since these signals represent the software's intention for the projector to follow.
- the software program generates the X-Y beam positions and beam power level "command signals" and periodically transfers these as digital data to the digital-to-analog converters in the interface circuit board.
- command signals any suitable interface hardware and software may be used to control any of the three projector types mentioned above.
- preferred hardware and software systems include the QuadModTM series of hardware boards and Lasershow DesignerTM series of laser software, both from Pangolin Laser Systems, Orlando, Florida.
- the X and Y beam position signals generated by the X-Y scanners are mathematically differentiated to produce an output equivalent to X and Y beam velocity.
- the X and Y beam velocities are added together to produce the total beam velocity.
- This total beam velocity is monitored (compared to some pre-set minimum allowable velocity) to make sure that the beam velocity is sufficiently high. If the beam were to stop (producing zero velocity) or the velocity were to otherwise drop below some preset threshold, this would be considered a "scanning failure".
- the beam may be completely turned off by the light beam modulator or by a shutter. This type of system is called a "scan-fail monitor".
- a scan-fail monitor is most often implemented in the form of analog signal conditioning components, but may also be implemented with computer hardware and software.
- a typical scan-fail monitor as know in the art is shown in Figure 5. While scan-fail monitors provide some level of protection for the audience, there are a number of problems that still remain. First, a scan-fail monitor does not provide automatic power level control in different regions of the scan field. For example, scan-fail monitors are not capable of allowing a higher power level over the audience's heads or below their eyes. Second, scan-fail monitors can be easily "fooled” into believing that there is a safe condition when there is not, because they only monitor the rate of change of position and do not track the actual position of the beam.
- the scan-fail monitor may allow this condition since the beam is technically scanning.
- a 50% concentration of beam power could be hazardous. Therefore, improvements are still required over the use of a scan-fail monitor alone.
- the actual process of evaluating the show material being projected into an audience is an extremely time consuming task which is prone to error.
- the current state of the art requires a beam power meter capable of measuring irradiance (beam power per unit area), a fast silicon photodiode, an oscilloscope, a scientific calculator, and sufficient skill to use these instruments.
- the beam power meter must be used to measure the "static beam irradiance at the closest point of audience access”.
- the fast silicon photodiode and oscilloscope are used together to measure the pulse characteristics of the scanning light beam.
- the scientific calculator is used to perform calculations using the irradiance and pulse characteristics to evaluate whether the effect is safe or not. While performing an evaluation of the show, each effect must be evaluated for three separate criteria, often termed maximum permissible exposure (MPE) levels, as described in well established safety standards including the IEC 60825-1 and the ANSI Z136.1.
- MPE maximum permissible exposure
- the three criteria are the single pulse MPE, multiple pulse MPE, and average power MPE.
- the scanning effect must not exceed any of these three MPE levels in order to be considered safe.
- single pulse and “multiple pulse” refer to a phenomenon that the human eye perceives due to the scanning action.
- a laser beam scans across the pupil of the viewer's eye, it is said to deliver a pulse of laser light to the viewer's eye. This is because as the beam scans past the viewer's eye, it will only enter the eye for a brief time, depending on the beam diameter and the scan rate.
- This perceived pulse of light created by the scanned beam is similar to a pulse that is created by a beam which is not scanning, but is turned on for only a brief instant.
- the amount of time that the beam is on within the viewer's pupil is called the pulse width. For audience scanning shows, this pulse-width is typically between about 20 to 500 microseconds.
- an audience scanning effect such as a tunnel or sheet scan
- this is done by repeatedly scanning the tunnel or sheet to make it appear solid.
- the beam crosses the viewer's eye, it will generate a pulse of light entering the eye.
- the X-Y scanners will trace this effect many times to make it appear to be solid, the viewer's eye may receive multiple pulses of light if the effect and viewer are stationary.
- the reason why pulses and multiple pulses are important, is that safety standards prescribe a maximum amount of light, that is, a maximum permissible exposure (MPE) that the viewer can be receive for a single pulse, and for multiple pulses.
- MPE maximum permissible exposure
- the current invention completely eliminates the need for manual and tedious evaluation of the scanned laser output. It does this by using a computer algorithm that monitors beam position and beam power, and by generating a correction signal and applying this correction signal to reduce the beam power, if a reduction is needed.
- the present invention makes use of a memory structure so that a minimum of computational power is required to perform these tasks. This allows the system to process the data, generate the correction signal, and reduce the power in real time, while the software is running on currently available personal computers.
- This invention also generates a visual display which can be used to monitor the hazard potential of the scanning beams, thus providing information to the user.
- the information garnered by an operator observing the visual display may be used to change the show so as to reduce or eliminate any original hazard potential, or to create an artistically improved show.
- This invention may be integrated with the same computer that generates the "command signals.”
- the present invention advantageously provides an Intelligent beam power attenuation system which monitors the instantaneous position and instantaneous beam power of a scanning light beam, generates a correction signal, applies this correction signal when needed, and controls the output beam power based on the maximum power allowed at that instantaneous position.
- MPA maximum power allowed
- the present invention additionally provides an intelligent beam power monitoring system which can be used to visually illustrate the accumulated beam power and thus, shows the potential eye hazards that exist in different regions of the scan field.
- This display may be effected as an integral part of the intelligent beam power attenuation process, or as a separate and/or optional process.
- FIG. 1 illustrates an audience scanning projector according to an embodiment of the present invention
- FIG. 2 shows another embodiment of the present invention
- FIG. 3 depicts yet another embodiment of the present invention
- FIG. 4 shows a prior art audience scanning projector employing a scan-fail monitor
- FIG. 5 illustrates a typical scan-fail monitor that exists in the current state of the art
- FIG. 6 shows how three separate lasers can be combined into a single beam for use in the present invention.
- FIG.7 shows the X-Y data points commanded by the programmable controller "command signals" and the circular shape that results by using a connect-the-dots drawing method
- FIG. 8 shows a bitmap memory structure used by one possible embodiment of this invention, and how the position of the X-Y data points correspond to bitmap locations;
- FIG. 9 is a flow diagram depicting a process for creating a visual display of accumulated beam power
- FIG. 10 shows a flow diagram of a process for generating a visual display of average beam power
- FIG. 11 depicts a process for visually displaying a histogram of scanned positions
- FIG. 12 illustrates a process for generating a visual display of pulse width at a predetermined X-Y position
- FIG. 13 shows a process for a simple beam power attenuation system capable of automatically limiting the instantaneous beam power based on X-Y position
- FIG. 14 is a flow diagram showing a process for creating a more complex beam power attenuation system capable of automatically limiting the instantaneous beam power based on the MPE levels and based on X-Y position.
- the term "light beam modulator” is used to describe a device which may be separate from the laser itself and which can control the power of the laser, for example, an acousto-optic modulator.
- the term may also be used to describe one or more laser power supplies if direct laser modulation is used.
- the invention in an apparatus for projecting a high intensity light beam such as a laser beam, provides the ability of monitoring the beam position as well as the beam power of the light beam. Monitoring may be accomplished by directly measuring the beam position and beam power, or indirectly by predicting the probable beam position and beam power using a version of the command signals that will be sent to X-Y scanners and light beam modulators. The "direct measurement” and “indirect prediction” methods are discussed in the next few paragraphs. DIRECT MEASUREMENT OF BEAM POSITION AND POWER
- the light beam is scanned using a pair of galvanometer scanners arranged to scan in an X-Y configuration.
- These galvanometer scanners provide a feedback "position signal" that is directly proportional to the X and Y beam position or angle of incidence currently used by each scanner.
- these position signals may be appropriately scaled and then used as the direct measurement of X and Y Position of the light beam.
- a sample of the modulated laser beam power can be taken using a beam splitter within the projector, so light is directed to a silicon photodiode, cadmium sulfide cell, or other similar detector means.
- the output from these devices serves as a scaled direct measurement of the power of the light beam.
- the position signals and measured beam power are schematically illustrated in FIG. 3.
- the command signals that are used to drive the galvanometer scanners may also be used to predict the X-Y beam position since the command signals and position signals should be almost identical in practice; any difference between these two should be negligible for eye-safety purposes.
- the command signals feeding the light beam modulators may be used to predict the beam power since the command signals and actual light output should be almost identical in practice.
- the only information needed in addition to the command signals is appropriate scaling information which indicates how many meters position signals correspond to, and how many Watts or Watts per square centimeter the beam power command signals correspond to.
- the beam power may be interpreted in terms of radiant power in Watts, or in terms of irradiance in Watts per square centimeter.
- red, green and blue lasers may be combined into a single beam which is then fed to the X-Y scanners.
- the red, green and blue beam power control command signals would be appropriately scaled and then summed to provide an indication of the total beam power.
- these three may be treated as three separate signal entities.
- the prediction may require the use of a digital "filter” since X-Y galvanometer scanners and beam power modulators have limited frequency response characteristics that are generally equivalent to a second-order Bessel filter.
- This Bessel filter can be implemented as a finite impulse response or infinite impulse response digital filter.
- these command signals may be observed in real time, or they may be pre-stored as numbers within a file or other storage mechanism.
- the beam position and beam power must be represented in a numeric form suitable for use by a computer algorithm. If the beam position and beam power are directly measured, then they must be "digitized” to provide this numeric form. Such a system is shown in Figure 3. Note that the digitization process is done periodically, by taking samples of the beam position and beam power. The periodicity of digitization is called the sample rate. If the beam position and beam power are indirectly predicted, they are assumed to already exist in a digital numeric form, either pre-stored within a file, or directly generated by the programmable controller that will output the "command signals" samples for both the X-Y galvanometer scanners and the beam power modulators.
- the sample rate for either method would generally be in the range of 2OkHz to 40OkHz, with 3OkHz being the most common sample rate.
- the beam position would usually exist in the form of X and Y coordinates since these ultimately drive, and are sampled from X-Y galvanometer scanners. However, it is possible for the beam position to be represented in the form of azimuth elevation, magnitude direction, or any other multidimensional coordinate scheme.
- this invention may also produce a graphical display to aid an operator visualize the hazard potential of the beam.
- This graphical display preferably shows the entire X-Y scan field as a rectangular representation that is color coded or intensity coded. For example, the color green could represent a zone of safety, whereas yellow might represent a zone calling for increasing caution and red could represent a danger zone. Black, for example, could be used to represent areas from which the laser beam is absent.
- the display is preferably generated on a computer monitor and is based on calculations performed on the beam position and beam power level. Alternatively, the display could also be formed with LEDs.
- the display may be created as a separate process from the automatic system discussed in the last paragraph, or the display system may be an integral part of the attenuation system, where the display represents a visualization of the correction signal itself.
- a graphical display monitor is very instructive to operators, as it informs them when a hazardous scanning condition exists.
- the automatic system discussed above would reduce the beam powerto a safe level automatically, this reduction may destroy the artistic intention of the scanning effect. Therefore, the operator of the system may use the hazard potential information shown in the visual display as a tool that helps discover whether or not it is necessary to re-program that part of the show so as to maintain or improve artistic integrity.
- a data table is used to store the beam power levels and X-Y positions.
- This data table is preferably what is known in the art as a "bitmap" - that is, a rectangular area of memory, which is easily and directly addressed using the beam position coordinates.
- bitmap a data table
- bitmaps are used to generate computer graphics displays, where each pixel contains a color / intensity level at that X-Y location on a computer monitor.
- a bitmap is used in a novel and non-classical way to hold information about the maximum laser beam power desired, as well as historical trend information on the beam position and beam power level at each "pixel".
- the historical trend information is used along with the current beam position and beam power levels to determine whether or not a correction of the beam power is needed. It is also used to generate a visual display of the hazard potential or other scanning characteristics.
- the bitmap used in this invention comprises a rectangular array of memory.
- the number of pixels within this bitmap may be adjusted to the resolution requirements of the application, but will generally range from approximately 63 pixels horizontally by 63 pixels vertically, to approximately 1023 pixels horizontally by 1023 pixels vertically, with 255 pixels horizontally by 255 pixels vertically being used most often.
- a greater number of pixels may offer a higher-resolution representation of historical trends mentioned above, but this comes at the expense of the greater memory requirements needed to support the larger number of pixels.
- bitmap has been described as a rectangular grid addressed by X-Y beam position coordinates, it is also possible that the bitmap may be a spherical grid addressed by azimuth-elevation coordinates, or magnitude-direction coordinates (both of which may be referred to as polar coordinates). In reality, the bitmap is nothing more than an n-dimensional array of memory elements being addressed by beam position coordinates, no matter how those beam position coordinates are specified, and no matter how the memory elements are organized.
- the present invention is primarily directed to laser projector safety, and especially to laser safety calculations as they pertain to the human eye.
- the MPE levels within safety standards are based on a dark-adapted 7mm pupil diameter.
- the spatial size of one pixel would preferably be at least 7mm wide by 7mm high.
- the spatial size of each pixel may be hard coded into an algorithm, or it may be specified directly by the user, or indirectly by the user inputting values that correspond to the horizontal and vertical size of the audience being evaluated.
- the numeric value of the beam position coordinates are used. At times, these beam position coordinates may have a different numeric range and resolution than the bitmap being used by this invention.
- the X and Y beam position coordinates may be digitized to produce a 16-bit value, providing a 0 to 65535 numeric range for each axis. If the bitmap that is used has a resolution of 255 by 255 pixels, then the numeric value of the X and Y beam position coordinates must be scaled appropriately such that when a number that represents "far left” for the X beam position coordinate, this number will also represent "far left” in the bitmap.
- bitmap pixel coordinate beam position coordinate * (number of bitmap pixels / numeric range of beam position coordinates).
- bitmaps are referred to in the art of computer graphics as a
- pixel aliasing may be undesirable since it sometimes results in images looking rough or jagged.
- pixel aliasing may actually be beneficial since it guarantees that multiple close scans of the laser beam will usually be resolved to the same bitmap pixel, thus helping to reinforce the application of this algorithm in the context of "head space” mentioned above. Even if a close scan of the laser were resolved to a pixel adjacent to pixel coordinate 116, this would not be detrimental in the context of the invention, since it would mean that such a scan was necessarily in a different location and thus, most probably scanning across a different eye-position or different viewer.
- anti-aliasing When anti-aliasing techniques are used, multiple pixels are addressed using a single beam position coordinate, with a weight given to up to four pixels, each weight being based on the fractional component of the pixel address.
- anti-aliasing and the way that it is applied is well known in the art of computer graphics.
- bitmap as disclosed in the present invention simplifies the task of safety evaluation, since the far left of the audience represents far left in the bitmap, and the far right in the audience represents far right in the bitmap, and also since the resolution of the data extracted is solely dependent on the resolution of the bitmap itself.
- the data elements stored in each pixel, and retrieved from each pixel location correspond to the desired brightness level of each pixel.
- These brightness levels may be of three separate colors (red, green and blue) and may also include a transparency (alpha) value.
- a computer program stores desired brightness levels into this bitmap, and later, when it becomes necessary to display the data on a computer monitor, the computer monitor will "scan" (retrieve) each bitmap pixel location and output the red, green and blue values to the Intensity signals on a computer monitor.
- the transparency (alpha) value is not used directly by the computer monitor itself, but instead may be used by computer graphics programs that are storing the red, green and blue brightness level data into the bitmap.
- a computer program that is about to store a red/green/blue brightness level into the bitmap may first read the current transparency level for that pixel, use this transparency level to perform a calculation on the red/green/blue brightness level that is about to be stored, and then finally store the red/green/blue brightness levels into the pixel location.
- each pixel location of the bitmap will generally include the following: • total accumulated beam power at this pixel; average beam power at this pixel; total number of times this pixel has been scanned; average number of times this pixel has been scanned; time when this pixel was first scanned by the beam; • time when this pixel was last scanned by the beam; pulse width experienced at this pixel; and maximum power allowed at this pixel.
- the “total accumulated beam power at this pixel” is computed by simply adding the instantaneous beam power to the current value stored in the "total accumulated beam power at this pixel". This value may be used to monitor and visualize the total power delivered in each area of the audience.
- This data element may also consist of separate data elements for red, green and blue beam power, if it is desired to monitor and attenuate these separately.
- the “average beam power at this pixel” is related to the "total accumulated beam power at this pixel", in that it represents a beam power that is accumulated over time, and it is calculated using the instantaneous beam power as an input.
- the "average beam power at this pixel” requires an additional level of computation in order to produce a value that represents an average overtime. This may be calculated using any number of techniques known in the art of computer programming for calculating a running average, but one simple and effective method is to use what is known as a "leaky bucket” technique, whereby the value stored in this location is periodically decreased by a small predetermined amount, and where the periodicity of this action and the amount of decrease controls the amount of time that is used for the averaging function.
- This value may be used to monitor and visualize the average power that is being delivered to each area of the audience, and this value may also be used for the purposes of "average MPE" calculations.
- These data elements may also include separate data elements for red, green and blue beam power, if it is desired to monitor and attenuate these separately.
- total number of times this pixel has been scanned is computed by simply incrementing this value each time the X-Y pixel coordinate enters this location.
- this value may also be used for visualization purposes to illustrate the frequency with which the beam is directed to this part of the scan field. This value may also be used for the purposes of "multiple pulse MPE" calculations.
- the "average number of times this pixel has been scanned” is computed in a similar way as the “total number of times this pixel has been scanned” and the “average beam power at this pixel”, whereby this value is increased each time the X-Y pixel coordinate addresses this location, and some averaging function is used to produce a time-averaged value. As with the "total number of times this pixel has been scanned", this value may be used for the purposes of visualization, and also for the purposes of "multiple pulse MPE" calculations.
- time when this pixel was first scanned by the beam” and "time when this pixel was last scanned by the beam” are not really computed values, but instead these locations are used to store the "time” value when the X-Y coordinate addressed this pixel location.
- These "time” values may be represented in microseconds, milliseconds, samples, or any other form that is convenient to be observed and consumed by the invention. These time values may be used to form a visual display, or they may be used to aid in the calculation of the pulse width, as required for "single pulse MPE” and “multiple pulse MPE” calculations.
- the "pulse width experienced at this pixel” is the calculated pulse width experienced at this pixel location. Note that, depending on the implementation of the algorithm, this may represent the time it takes for the beam to enter, and then leave the actual pixel's X-Y location (i.e. truly the pulse width experienced by the pixel), or it may be a calculated value of the pulse width experienced by any 7mm pupil within the region of this pixel. Since all of the laser safety standards are based on a 7mm eye pupil, the pulse width across a 7mm pupil must be known at some point in order to perform the "single pulse MPE" evaluation.
- the pulse width experienced by a 7mm pupil may be calculated in one of several ways.
- One other way to calculate the pulse width is by using the beam velocity, and calculating the pulse width from this beam velocity as it scans across a 7mm pupil. This beam velocity can be calculated by using multiple beam position samples.
- the algorithm may not have access to past or future beam position samples, only to the current beam position sample.
- the invention would make handy use of a global variable to store the value of the beam position in a variable called "last beam position". In this way, for each data sample, the algorithm could subtract the current beam position from the last beam position and find the difference (length).
- the "maximum power allowed at this pixel" may be used as an additional form of control over the beam power. This may be used to allow the beam power to be higher than the safety calculations allow, if the user has areas where they know there will not be viewers present (i.e. to allow a higher power over the head of the audience). Or it may be used to reduce the amount of power regardless of the results of the safety calculations (i.e. to forcibly reduce power to zero in very sensitive areas).
- This data element may or may not be used, depending on the complexity of the user interface and the application, but if used, this data element would be input by the user, and usually specified by using a tool like a paint program on a computer, allowing the user to specify (by painting) appropriate power levels for each pixel. This data element may also consist of separate data elements for red, green and blue beam power, if it is desired to monitor and attenuate these separately.
- each pixel location it may be desirable to store other data elements in each pixel location. Some examples include total accumulated pulse time (sum of all pulse widths experienced by the pixel), average pulse width, maximum number of times this pixel has been scanned within a 10 second period of time, last correction signal applied at this pixel, etc. It may also be desirable to compute and store these data elements for the purposes of monitoring and visualization, or for attenuation, depending on the application.
- the algorithm processes this information by computing and storing data elements at each pixel location as described above, and also by performing comparisons to see if the current beam power is above a threshold which is determined either by the maximum power allowed at this pixel data element, and/or by performing safety calculations based on the pulse width-, number of pulses-, and average power-related data elements found at that pixel location. If the current beam power is above the threshold, then a correction signal is calculated. This Correction Signal is proportional to the amount by which the beam power must be reduced.
- the correction signal may be applied directly (mathematically) to the beam power before it is output by the programmable controller (if the algorithm is an integral part of the software within the programmable controller) or this correction signal may be output as a separate electrical signal or data element which may be used to control the laser projector.
- the correction signal may consist of separate values for red, green and blue, if it is desired to monitor and attenuate these separately. Note that, depending on the implementation of the software and programming language used to implement the invention, the correction signal may not exist in the form of an explicit variable, but instead may be implicit within the expression that applies the correction. Examples of each form are shown below:
- beam power maximum power allowed at location
- the correction signal be applied to the beam power at each pixel and each numeric data sample interval, it is also possible that the correction signal may be applied to numerous pixels and/or over numerous data sample periods. When the correction signal is applied in this way, the visual result would be that the power of the entire projected image is reduced in an area, instead of just one small part of the projected image.
- the present invention may be used to create a monitor to visually display any of any of the parameters in the bitmap.
- the visualization may use the average beam power-related data element of each pixel in the bitmap to produce a visual representation on a display screen.
- This representation or visual display might indicate a predetermined color, for example, green, if the average beam power is sufficiently low so it would not create a hazard.
- a second color, perhaps yellow, would indicate that the average beam power is nearing the point of a hazard.
- a third color possibly red, would indicate that the average beam power is hazardously high.
- the average beam power is a very valuable data element for this purpose since it will be illustrative of energy concentrations within the scan field.
- Other data elements in the bitmap may also be monitored and visualized in a similar fashion.
- the visualization may use the pulse width-related data element of each pixel to produce the visual display, where green represents a very short pulse-width, yellow represents a medium-length pulse width, and red represents a very long pulse-width.
- Another example would be to monitor and visualize the correction signal itself, where green represents no correction, yellow represents a moderate correction, and red represents a significant correction.
- the visual representation can be generated in a display screen or computer monitor by evaluating data stored in each pixel in the bitmap described in this invention, performing the necessary conditioning based on the data (example, green - yellow - red) and then placing this conditioned information onto the display screen. Since computer monitors are based on the concept of bitmaps, it will be appreciated that this monitoring and visualization operation is not much more complicated than transferring information from storage in the bitmap of this invention, to display on the bitmap of a the screen display.
- bitmap data elements as well as the green-yellow-red color scheme mentioned above is meant only as exemplary for conceptualizing the invention only, and is not intended to be a limiting factor in this invention. Any one of the data elements stored in the bitmap, or even combinations of data elements may be used to create the displayed visualization, and the visualization may be implemented as any color or intensity scheme.
- the invention discloses a projection system 1 for projecting beams and patterns of light into an audience of viewers 19.
- the projection system 1 includes a programmable controller 4, which produces X-Y beam position coordinates 6 and beam power coordinates 5. These coordinates are produced by reading image data from a file 2, or by synthesizing these coordinates by executing an algorithm to generate abstract imagery 3, or by some combination of the two.
- the X-Y beam position coordinates 6 and beam power coordinates 5 are in a digital numeric form, suitable for processing by software resident in a computer.
- the X-Y beam position coordinates 6 are scaled based on the width of the audience information supplied by the user Interface input 12, and then used to address data stored in table of data elements 11.
- the data elements including information related to the maximum power allowed at that X-Y location, as well as information related to the number of times that data element has been addressed, and accumulated beam power at that X-Y location.
- the programmable controller 4 processes these data using a software program which determines if the beam power coordinate 5 exceeds the maximum power allowed at that location.
- a correction signal 7 is generated and applied to the beam power coordinate 5, resulting in corrected beam power 30.
- the programmable controller 4 sends the X-Y beam position coordinates 6 as well as the corrected beam power coordinate 30 to a digital to analog Interface 8, which supplies command signals 9 to the scanning and light modulation systems described below.
- the beam power portion of the command signals 9 is fed to a light beam modulator 16, which modulates the light beam from the laser 14.
- the beam power portion of the command signals 9 is fed directly to the laser power supply 15 which then directly modulates the power of the laser.
- the X-Y beam position portion of the command signals 9 is fed to an X-Y scanning system 17 which produces scanning beams 18 in the direction of the viewing audience 19.
- FIGS. 1 and 2 a difference between the embodiments shown in FIGS. 1 and 2 resides in the process for modulating the light beam.
- Figure 1 shows an embodiment in which the light beam is modulated by a light beam modulator 16. Such would be the case when the laser 14 is producing a continuous light output as, for example, in a gas laser.
- FIG. 2 shows an embodiment in which the light beam is modulated by its own power supply 15. An example of this type of embodiment would be a solid state laser.
- FIG. 3 discloses a completely different approach.
- the programmable controller monitors the beam power coordinate information and generates the command signals.
- the monitoring software resides external to the programmable controller and runs on a completely separate processor.
- programmable controller 4 produces X-Y beam position coordinates 6 and beam power coordinates 5 by reading image data from a file 2, or synthesizes these coordinates by executing software to generate the abstract imagery 3, or by some combination of the two.
- the programmable controller 4 does not generate or apply any correction to the beam power and instead, it sends the X-Y beam position coordinates 6 as well as the beam power coordinates 5 directly to the digital to analog Interface 8, which supplies command signals 9 to the X-Y scanning system 17 and to the correction signal application circuit 30.
- Light produced by laser 14 passes through light beam modulator 17 and is measured by the photodetector 22 by virtue of a beam splitter 21. This results in measured beam power signal 23.
- the measured beam power signal 23 and the measured position signals 24 from the X-Y scanning system 17 are directed to a digitizing system 25 which periodically digitizes the signals and converts them to digital numeric form required for the algorithm of this invention.
- the X-Y beam position coordinates portion of 26 are scaled based on the width of the audience information supplied by the user interface input 12. They are then used to address data stored in table of data elements 11 , the data elements including information related to the maximum power Allowed at that X-Y location, as well as information related to the number of times the particular data element has been addressed in the past, and accumulated beam power at that X-Y location.
- Processor 27 processes these data through software which determines if the beam power portion of 26 exceeds the maximum power allowed at that location. If it does, then a correction signal 7 is generated and applied to the beam power portion of command signals 9 using an electronic circuit 20, resulting in a corrected beam power signal 30.
- a variety of possible visualizations are shown on a display 10.
- This visual representation is generated using the X-Y position coordinates 6, the corrected beam power coordinates 30, and other information found in the table of data elements 11.
- the visual representation shows the X-Y scan field in the form of a rectangular display, with green portions of the visualization indicating complete safety, yellow portions indicating impending hazard, red portions indicating severe hazard and black portions indicating that no laser light has entered that area. Processes for generating the visual display are shown in the flow diagrams of FIGS. 9-12.
- the present invention may be partially or fully embodied within a computer algorithm.
- this algorithm requires the beam position and beam power, as well as spatial-related information, including the size of the audience, beam diameter, and possibly beam power scale factor (if indirect prediction is used).
- the algorithm processes these data, generates correction signal, and applies this correction signal to the beam power.
- this correction signal is applied directly to the beam power "command signals" that are generated by the programmable controller and then these command signals are output to the laser projector. In this manner, the programmable controller will never output command signals which would result in an unsafe exposure.
- the technique is shown in FIGS. 1 and 2.
- the invention may be embodied as two separate components, whereby one component calculates and generates the correction signal, and a separate component performs the beam power attenuation process.
- the second device may be another beam power modulator, or it may be an electronic circuit which modifies the original beam power "command signals" based on additional criteria. This approach is shown in FIG. 3.
- the invention was characterized in the context of using the beam position (or sampled position signal) coordinates to address a memory table, the table preferably being implemented as a bitmap-like memory structure.
- this table may also be constructed using linear arrays, since bitmaps themselves are essentially linear arrays.
- the table may also be implemented as a linked list or double-linked list or other types of table structures which are well known in the art of data processing, provided that there is an adequate method of identifying data elements within the table using the beam position coordinates.
- This table may also be implemented as a multi-dimensional array whereby not only the beam position coordinates, but also the beam power may be used as a table-addressing coordinate.
- this invention provides that only those table elements that are identified periodically by beam position coordinates may be accessed and modified. It is not necessary to analyze all data elements in the table for the purposes of this invention.
- Pixels may actually be considered "regions", with each region generally being the size of a pupil of a human eye or larger.
- the principles embodied in the invention may also be used in other types of radiant energy beams, and applications where it is desirable to prevent an undesirable level of exposure, particularly if such exposure results in a build-up of power that results from a radiant energy beam repeatedly being directed over a scanning area.
- Such applications include fiber optic switching and selection, materials processing, and flying aircraft avoidance for "guide star" lasers used in astronomy, or even aircraft avoidance for search lights.
- this invention can be easily adjusted to accommodate the requirements of other safety standards or beam power limiting requirements. Some of these adjustments may include removing the single-pulse MPE and multiple-pulse MPE calculations and performing calculations only on the basis of average beam power. This would especially be the case in fiber optic switching and material processing applications. Other possibilities include basing the evaluations and calculations purely on the average or total number of times that the beam scans across each pixel or region (total number of pulses).
- this invention may also be used to evaluate and correct prestored data samples as well.
- the pre-stored data samples would be samples of the beam position and beam power, stored within a file or other storage means. Such a file is shown in FIGS. 1-4.
- the correction signal may be applied directly to correct the data and then store the corrected data.
- the correction signal may be stored itself as a separate entity that may be applied later, when the prestored data is consumed.
Abstract
Description
Claims
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US65028305P | 2005-02-04 | 2005-02-04 | |
PCT/US2005/040418 WO2006052961A2 (en) | 2004-11-05 | 2005-11-07 | Audience scanning light projector and associated methods |
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EP1851583A2 true EP1851583A2 (en) | 2007-11-07 |
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EP05826155A Withdrawn EP1851583A2 (en) | 2004-11-05 | 2005-11-07 | Audience scanning light projector and associated methods |
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AU (1) | AU2005304657B2 (en) |
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CN110023834A (en) * | 2016-12-01 | 2019-07-16 | 奇跃公司 | Projector with scanning array light engine |
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US7301558B2 (en) * | 1996-02-27 | 2007-11-27 | Media Technologies Licensing, Llc | Imaging system and method |
US6583772B1 (en) * | 1998-08-05 | 2003-06-24 | Microvision, Inc. | Linked scanner imaging system and method |
US6919892B1 (en) * | 2002-08-14 | 2005-07-19 | Avaworks, Incorporated | Photo realistic talking head creation system and method |
US6867753B2 (en) * | 2002-10-28 | 2005-03-15 | University Of Washington | Virtual image registration in augmented display field |
EP2408192A3 (en) * | 2004-04-16 | 2014-01-01 | James A. Aman | Multiple view compositing and object tracking system |
US7576757B2 (en) * | 2004-11-24 | 2009-08-18 | General Electric Company | System and method for generating most read images in a PACS workstation |
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- 2005-11-07 AU AU2005304657A patent/AU2005304657B2/en active Active
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Cited By (3)
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CN110023834A (en) * | 2016-12-01 | 2019-07-16 | 奇跃公司 | Projector with scanning array light engine |
CN110023834B (en) * | 2016-12-01 | 2021-09-14 | 奇跃公司 | Projector with scanning array light engine |
US11599013B2 (en) | 2016-12-01 | 2023-03-07 | Magic Leap, Inc. | Projector with scanning array light engine |
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WO2006052961A2 (en) | 2006-05-18 |
AU2005304657B2 (en) | 2011-11-17 |
AU2005304657A1 (en) | 2006-05-18 |
WO2006052961A3 (en) | 2008-05-29 |
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