Patent Publication Number: US-2023162583-A1

Title: Operating a scanning smoke detector

Description:
PRIORITY INFORMATION 
     This application is a continuation of U.S. application Ser. No. 17/513,316, filed Oct. 28, 2021, the contents of which are incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to apparatuses, methods, and computer-readable media for operating a scanning smoke detector. 
     BACKGROUND 
     Smoke detection methods, devices, and systems can be implemented in indoor environments (e.g., buildings) or outdoor environments to detect smoke. As an example, a Light Detection and Ranging (LiDAR) smoke detection system can utilize optical systems, such as laser beam emitters and light receivers, to detect smoke in an environment. Smoke detection can minimize risk by alerting users and/or other components of a fire control system of a fire event occurring in the environment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a block diagram of an example apparatus in accordance with one or more embodiments of the present disclosure. 
         FIG.  2    illustrates an example apparatus in accordance with one or more embodiments of the present disclosure. 
         FIG.  3    illustrates another example apparatus in accordance with one or more embodiments of the present disclosure. 
         FIG.  4    illustrates another example apparatus in accordance with one or more embodiments of the present disclosure. 
         FIG.  5 A  is a top view of an area including an apparatus in accordance with one or more embodiments of the present disclosure. 
         FIG.  5 B  is a top view of the area including the apparatus for detecting smoke and an object in accordance with one or more embodiments of the present disclosure. 
         FIG.  5 C  is another top view of the area including the apparatus for detecting smoke and an object in accordance with one or more embodiments of the present disclosure. 
         FIG.  6    illustrates a method for operating a scanning smoke detector in accordance with one or more embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Apparatuses, methods, and computer-readable media for operating a scanning smoke detector are described herein. One or more embodiments include a laser emitter configured to emit a beam of light, a rotational component configured to rotate the emitter such that the beam periodically scans across an area, and a light receiver configured to receive a reflected portion of the beam of light and determine a presence of smoke particles in the area based on the reflected portion, wherein the smoke detection apparatus is configured to operate at a first power level, decrease the beam to a second power level responsive to a determination that an object in the area is in a path of the beam, and increase the beam to the first power level responsive to a determination that the object is no longer in the path of the beam. 
     Certain smoke detection systems may use one or more laser beam emitters in conjunction with one or more light receivers to detect smoke. For example, a smoke detection system may use Light Detection and Ranging (LiDAR) technology to detect smoke. When a beam of laser light is emitted in an indoor environment, it may encounter an object, substance, or material (e.g., smoke particles) and light may be reflected and/or scattered to the light receiver. If no object, substance, or material is present in the path of the laser, the light will instead reflect and/or scatter off a wall of the indoor environment and back to the light receiver. The smoke detection system can determine the difference between a received light signal that has been reflected and/or scattered off a wall or light reflected off another object, substance, or material, because the intensity of the received light signal will be considerably greater if it has been reflected and/or scattered off a wall as opposed to reflecting and/or scattering off a substance such as smoke. Additionally, a light signal that has passed through smoke will be slightly attenuated. 
     As such, by rotating a laser beam emitter and light receiver of a scanning smoke detector while emitting pulses of light from the laser beam emitter, an indoor environment can be scanned to detect smoke. In one example, such a scanning smoke detector may be positioned in a corner of an area (e.g., room) and rotated from zero to 90 degrees to scan the entire area for smoke. In another example, such a scanning smoke detector may be positioned on a wall of an area and rotated from zero to 180 degrees to scan the entire area for smoke. In another example, such a scanning smoke detector may be hung from a ceiling of an area and rotated 360 degrees to scan the entire area for smoke. By recording the alignment, position, and orientation of the scanning smoke detector at the time that the smoke is detected, the approximate location of the smoke can also be determined. 
     Scanning smoke detectors can operate to detect smoke in relatively large areas. For instance, in some cases, scanning LiDAR smoke detectors can have an effective range of up to 100 meters, making them particularly effective for use in large open indoor spaces such as warehouses, airports, sports facilities, etc. The smoke detection sensitivity provided at longer range allows a single product installation to replace more of the spot detectors conventionally used. In a large open area, the number of spot detectors that can be replaced by a single LiDAR system increases with the square of the range. For example, a 100-meter range LiDAR scanning detector could replace four times as many spot detectors as a 50-meter range unit, at substantially the same installed cost. 
     The laser source used in such a detector can produce a beam made up of repeated pulses of laser light repeated at an interval. For example, a five nanosecond pulse can be repeated every 600 nanoseconds. These pulses are produced at a power level sufficient to cause the light scattered backwards from a plume of smoke to be economically detected. Because smoke may be of relatively low concentration, dark in color, and distant from the emitter/receiver, the instantaneous laser power used may be relatively high (e.g., in the order of tens of Watts). 
     However, high powered laser light presents the risk that the pulses could be damaging to human eyes. Even though a scanning smoke detector may be located at an elevation where the presence of people is relatively rare (e.g., near a ceiling), the risk of eye damage is nontrivial. A user performing maintenance or engaging in other tasks may place themselves in the path of a scanning smoke detector. Laser systems that are of insufficient power to cause eye damage are classified as “Class 1” according to the classification system as specified by the International Electrotechnical Commission (IEC) 60825-1 standard. Under this standard, class 1 systems are allowed to be operated in locations where people are present without special precautions, such as the permanent attendance of a trained operator. “Class 1” is therefore the preferred classification for any laser system that operates autonomously. 
     Previous approaches may employ mitigation techniques to avoid the potential for eye damage from high power lasers. Some previous mitigation techniques allowing laser systems to operate at a higher power include the use of optical lensing to cause the laser beam to be significantly wider than the diameter of the pupil of the human eye. Standards in force for laser eye safety are complex but may be generally considered to operate under the assumption that the human pupil may dilate to up to seven millimeters. Thus, a system may be considered generally “eye safe” (e.g., not damaging to the human eye) if the net power entering the eye via the pupil is within a defined limit. Laser systems using such techniques are classified as “Class 1M,” where the “M” signifies that the system may not be “eye safe” if magnifying optics are in use. If a person is using an optical magnifier, such as binoculars, then the effective aperture for light to enter the eye is much wider and, consequently, the total power focused on the person&#39;s retina could be damaging. 
     Embodiments of the present disclosure can provide Class 1 smoke detection by protecting people from the potentially damaging effects of powerful laser light, even if those people are using magnifying optics. For instance, some embodiments provide a safety “interlock” system that uses the LiDAR signal itself to determine if a solid object (e.g., a person) has entered the current path of the beam. In some embodiments, an initial eye-safe low-power “exploratory” pulse can be produced to determine the presence of a solid object. Embodiments herein can thereafter avoid generating subsequent high-power and potentially eye-damaging pulses until the obstruction has been removed. The response time for power reduction can be in the order of 1 micro-second, so embodiments of the present disclosure can prevent a person using binoculars or the like to align them before the interlock system has reacted. This may permit a commercially advantageous classification for the system as Class 1 rather than Class 1M. 
     In the following detailed description, reference is made to the accompanying drawings that form a part hereof. The drawings show by way of illustration how one or more embodiments of the disclosure may be practiced. 
     These embodiments are described in sufficient detail to enable those of ordinary skill in the art to practice one or more embodiments of this disclosure. It is to be understood that other embodiments may be utilized and that process, electrical, and/or structural changes may be made without departing from the scope of the present disclosure. 
     As will be appreciated, elements shown in the various embodiments herein can be added, exchanged, combined, and/or eliminated so as to provide a number of additional embodiments of the present disclosure. The proportion and the relative scale of the elements provided in the figures are intended to illustrate the embodiments of the present disclosure and should not be taken in a limiting sense. 
     The figures herein follow a numbering convention in which the first digit or digits correspond to the drawing figure number and the remaining digits identify an element or component in the drawing. Similar elements or components between different figures may be identified by the use of similar digits. For example, 201 may reference element “01” in  FIG.  1   , and a similar element may be referenced as  201  in  FIG.  2   . 
     As used herein, “a”, “an”, or “a number of” something can refer to one or more such things, while “a plurality of” something can refer to more than one such things. For example, “a number of components” can refer to one or more components, while “a plurality of components” can refer to more than one component. Additionally, the designator “N”, as used herein particularly with respect to reference numerals in the drawings, indicates that a number of the particular feature so designated can be included with a number of embodiments of the present disclosure. This number may be the same or different between designations. 
     As described herein, a fire control system may be any system designed to detect and/or provide a notification of fire events. For example, a fire control system may include smoke detection apparatuses and/or devices (e.g., apparatuses  100 ,  200 ,  300 ,  400 , and/or  500 ) that can sense a fire occurring in the facility, alarms (e.g., speakers, strobes, etc.) that can provide a notification of the fire to the occupants of the facility, fans and/or dampers that can perform smoke control operations (e.g., pressurizing, purging, exhausting, etc.) during the fire, and/or sprinklers that can provide water to extinguish the fire, among other components. A fire control system may also include a control unit such as a physical fire control panel (e.g., box) installed in the facility that can be used by a user to directly control the operation of the components of the fire control system. In some embodiments, the fire control system can include a non-physical control unit or a control unit located remotely from the facility. 
       FIG.  1    is a block diagram of an example apparatus  100  in accordance with one or more embodiments of the present disclosure. As shown in  FIG.  1   , the apparatus  100  includes a light emitter  101 , a receiver  105 , a rotational component  106 , a processor  108 , and a memory  110 . The light emitter  101  (sometimes referred to herein as “emitter  101 ”) can be any device, system, or apparatus configured to emit light. As used herein, the terms “light” or “beam” can include any type of radiation beam, such as a beam of laser light. These terms can also include pulses of light. The light emitted can be pulses, such as pulses of lasers. In some embodiments, the emitter  101  is a LiDAR transmitter. The emitter  101  can operate at different power levels, as described below. 
     The receiver  105  can include a sensor, detector, lens, or combination thereof configured to receive light and/or to convert light into a form that is readable by an instrument. In some embodiments, the receiver  105  is a LiDAR receiver or an electro-optical sensor. In some embodiments, the receiver  105  includes a clock or processing resources. The receiver  105  can be configured to measure the time taken for a pulse of light to travel from the emitter  101 , reflect and/or scatter off an object, substance, or material, and travel back to the receiver  105 . 
     As used herein, the term “reflected” may be used to refer to light that is not only reflected but may be reflected and/or scattered. For example, the light may be reflected off a surface at an angle of incidence equaling the angle of reflection. Light that is incident on a surface or material can also be scattered in a multitude of directions in accordance with embodiments of the present disclosure. The receiver  205  can be configured to receive a reflected portion of a beam of light emitted by the emitter  201  and determine a presence of smoke particles in the area based on the reflected portion. 
     The rotational component  106  is a component configured to rotate the light emitter  101 . In some embodiments, the rotational component  106  rotates the emitter such that the beam periodically scans across an area (discussed further below). The rotational component  106  can be mechanical and/or electrical. It may be configured to rotate the emitter  101  at a particular speed and/or over a given range. For example, if the apparatus  100  is positioned in a corner of a room, the rotational component  106  may alternately rotate the emitter  101  from 0 degrees to 90 degrees and from 90 degrees to 0 degrees. If the emitter  101  emits pulses periodically as the rotational component  106  moves, the apparatus  100  can scan an entire area for smoke. In some embodiments, the rotational component  106  rotates the receiver  105  and the emitter  101  together. For instance, the rotational component can be a rotary platform or table driven by a motor. 
     The memory  110  can be any type of storage medium that can be accessed by the processor  108  to perform various examples of the present disclosure. For example, memory  110  can be a non-transitory computer readable medium having computer readable instructions (e.g., computer program instructions) stored thereon that are executable by the processor  108  to perform aspects of one or more embodiments of the present disclosure. 
     Memory  110  can be volatile or nonvolatile memory. Memory  110  can also be removable (e.g., portable) memory, or non-removable (e.g., internal) memory. For example, memory  110  can be random access memory (RAM) (e.g., dynamic random access memory (DRAM) and/or phase change random access memory (PCRAM)), read-only memory (ROM) (e.g., electrically erasable programmable read-only memory (EEPROM) and/or compact-disk read-only memory (CD-ROM)), flash memory, a laser disk, a digital versatile disk (DVD) or other optical disk storage, and/or a magnetic medium such as magnetic cassettes, tapes, or disks, among other types of memory. 
     Further, although memory  110  is illustrated as being located in the apparatus  100 , embodiments of the present disclosure are not so limited. For example, memory  110  can also be located internal to another computing resource (e.g., enabling computer readable instructions to be downloaded over the Internet or another wired or wireless connection). The apparatus  100  can include hardware, firmware, and/or logic that can perform a particular function. As used herein, “logic” is an alternative or additional processing resource to execute the actions and/or functions, described herein, which includes hardware (e.g., various forms of transistor logic, application specific integrated circuits (ASICs)), as opposed to computer executable instructions (e.g., software, firmware) stored in memory  110  and executable by a processing resource (e.g., processor  108 ). 
     Processor  108  can execute the executable instructions stored in memory  110  in accordance with one or more embodiments of the present disclosure. For example, processor  108  can execute the executable instructions stored in memory  110  to decrease the beam to a second power level responsive to a determination that an object in the area is in a path of the beam. 
       FIG.  2    illustrates an example apparatus  200  in accordance with one or more embodiments of the present disclosure. As shown in  FIG.  2   , the apparatus  200  may include a light emitter  201  configured to emit a beam  203 . For example, the light emitter  201  may be a laser emitter, and the beam  203  may be a laser beam. In some embodiments, the light emitter  201  may be a photodiode or a laser diode. Although the beam  203  is illustrated in  FIG.  2    as a single beam of light, in some embodiments, the light emitter  201  may emit pulses of light. For example, the light emitter  201  may emit a beam  203  at a particular time interval. 
     As illustrated in  FIG.  2    the beam  203  may illuminate smoke particles (sometimes referred to simply as “smoke”)  217 . The smoke  217  (e.g., the presence of the smoke  217 ) may be detected by the apparatus  200  when the light forming the beam  203  is reflected from the smoke  217  to a light receiver  205  of the apparatus  200 . The light receiver  205  may be configured to receive reflected light as a result of the beam  203  encountering an object, substance, or material (e.g., smoke  217 ). In some embodiments, the light receiver  205  may be, for example, a LiDAR receiver (e.g., a LiDAR sensor). 
     The apparatus  200  can be configured to detect smoke based on light received through the light receiver  205 . For instance, the apparatus  200  may determine whether reflected light indicates the presence of smoke. The apparatus  200  may do so, for example, by measuring and analyzing the intensity of reflected light received by the receiver  205 . If the intensity of the reflected light is below a certain level, the processor may determine that smoke  217  is present. For example, the apparatus  200  may compare the intensity level of the reflected light to that which would be expected for light reflected against a wall or another hard object; if the comparison indicates the intensity level of the reflected light is less than the expected intensity, the apparatus  200  can determine that smoke  217  is present. 
     The apparatus  200  may also determine the location of the smoke  217 . For example, the apparatus  200  may be able to determine the location (e.g., the exact location) of the smoke  217  with respect to the light receiver  205  by measuring the amount of time between when the laser beam  203  pulse was emitted and when the reflected light was received by the light receiver  205 . 
     The apparatus  200  may also be configured to then take an action in response to detecting smoke. For example, although not illustrated in  FIG.  2    for clarity and so as not to obscure embodiments of the present disclosure, upon detecting smoke, the apparatus  200  may be configured to transmit a signal to a cloud, control panel, central monitoring system, user, or other device of a fire control system indicating the smoke has been detected. The apparatus  200  may also be configured to transmit data, such as motion of the emitter  201  and/or location of the smoke  217 , to any of the foregoing examples. Data may be transmitted from the apparatus  200  with a unique identifier for the area (e.g., a room) in which the apparatus  200  is located. The apparatus  200  may have embedded software for analyzing and transmitting data and/or for detecting smoke  217 . 
     The light receiver may include a first (e.g., primary) receiver lens  207  and a second (e.g., secondary) receiver lens  209 . The primary receiver lens  207  and the secondary receiver lens  209  may be, for example, Fresnel lenses. In some embodiments, the sizes of lenses  207  and  209  may be proportional to the size of the area to be monitored for smoke (e.g., the larger the area to be monitored for smoke, the greater the sizes of lenses  207  and  209 ). The secondary receiver lens  209  may be designed to collect light reflected from smoke  217  that is much closer to apparatus  200  than light reflected from smoke that is further away from apparatus  200  and within the field of view of the primary receiver lens  207 . Accordingly, the secondary receiver lens  209  may be significantly smaller in size than the primary receiver lens  207 . 
     In some embodiments, the primary receiver lens  207  may be a Fresnel lens of, for example, 90-110 mm in diameter. One or both receiver lenses  207  and  209  may be molded from clear plastic. The receiver lenses  207  and  209  may be disc-shaped with multiple concentric, grooved rings. This may allow the receiver lenses  207  and  209  to collect light and direct it to a photo-sensitive element within the light receiver  205 . In some embodiments, the secondary receiver lens  209  may be constructed by molding a small part of the primary receiver lens  207  at an angle to the remainder of the receiver lens  207 . This would effectively make the secondary lens  209  a smaller lens within the primary receiver lens  207 . 
     As shown in  FIG.  2   , the light emitter  201  and the light receiver  205  may be non-coaxial. For example, light emitter  201  may be positioned at an angle with respect to light receiver  205 , and the laser beam  203  emitted by light emitter  201  and the fields of view  211  and  213  of the primary and secondary receiver lenses  207  and  209 , respectively, may not be parallel, as illustrated in  FIG.  2   . As such, although the field of view  211  of the primary receiver lens  207  may include at least a portion of the beam  203  (e.g., field of view  211  partially overlaps the beam  203 ), a portion of beam  203  may be outside field of view  211  but not outside field of view  213 , such that the beam  203  may also illuminate smoke  217  that is positioned outside of the field of view  211  of the primary receiver lens  207 , but is not outside the field of view  213  of secondary receiver lens  209 . It is noted that while non-coaxial embodiments may be discussed herein, such discussion is not intended to be taken in a limiting sense. Embodiments of the present disclosure do not limit the particular arrangement and/or configuration of the optical elements of a scanning smoke detector. 
     In some embodiments, the secondary receiver lens  209  may be attached to the primary receiver lens  207 . For example, the secondary receiver lens  209  may be molded within the primary receiver lens  207 . Further, the secondary receiver lens  209  may be positioned at an angle with respect to the primary receiver lens  207 . As such, the field of view  211  of the primary receiver lens  207  may differ from the field of view  213  of the secondary receiver lens. Accordingly, the secondary receiver lens  209  may expand an overall field of view of the light receiver  205 . 
     The field of view  213  of the secondary receiver lens  209  may at least partially overlap with the field of view  211  of the primary receiver lens  207 . The field of view  213  of the secondary receiver lens  209  may include at least a portion of the beam  203 . For instance, field of view  112  may include portions of the beam  203  that may not be within the field of view  211  of the primary receiver lens  207 . Furthermore, the field of view  213  of the secondary receiver lens  209  may include (e.g., cover) a region  215  between an edge  211 - 1  of the field of view  211  of the primary receiver lens  207  and light emitter  201 . The edge  211 - 1  may be between the laser beam  203  and the second receiver lens  209 . Accordingly, the combined fields of view  211  and  213  of the primary and secondary receiver lenses, respectively, may capture the entire, or nearly the entire, beam  203 . 
     The angle at which the primary receiver lens  207  is positioned with respect to the secondary receiver lens  209  may correspond to how much of beam  203  can be captured. This angle may be determined based on, for example, a distance between the emitter  201  and the receiver  205 , an angle of the beam  203  with respect to the field of view  211  of the primary receiver lens  207 , and/or an angle of the field of view  213  (e.g., angle of view) of the secondary receiver lens  209 . 
       FIG.  3    illustrates another example apparatus  300  in accordance with one or more embodiments of the present disclosure. Some portions and/or elements of smoke detection apparatus  300  can be analogous to smoke detection apparatus  200  as shown and described in connection with  FIG.  2   . For example, field of view  311 , and field of view edge  311 - 1 , of primary receiver lens  307  can be analogous to field of view  211 , and filed of view edge  211 - 1 , respectively, of primary receiver lens  207  previously described in connection with  FIG.  2   . However, rather than a single light emitter (e.g., as shown in  FIG.  2   ), smoke detection apparatus  300  may include multiple light emitters  301 - 1  and  301 - 2 , wherein each light emitter  301 - 1  and  301 - 2  emits a different beam (laser beams  303 - 1  and  303 - 2 , respectively). Each light emitter  301 - 1  and  301 - 2  may be positioned on an opposite side of light receiver  305 , wherein the light receiver  305  is configured to receive light reflected by the beams  303 - 1  and  303 - 2  off of objects, substances, and materials, such as smoke  317 - 1  and  317 - 2 . 
     Further, the light receiver  305  of the smoke detection apparatus  300 , rather than including a primary receiver lens and a single secondary receiver lens (e.g., as shown in  FIG.  2   ), can include a primary receiver lens  307  and a number of secondary receiver lenses  309 - 1  and  309 - 2 . Secondary receiver lens  309 - 2  can ensure that smoke, such as smoke  317 - 2 , can still be detected, even if it is outside of the fields of view  311  and  313 - 1  of the primary receiver lens  307  and other secondary receiver lens  303 - 1 , and the emitter  301 - 2  can be non-coaxial with the light receiver  305 . 
     In some embodiments, the emitter  301 - 2  can be positioned outside of the region  315  between the first edge  311 - 1  of the field of view  311  of the primary receiver lens and emitter  301 - 1 . The field of view  313 - 2  of the emitter  301 - 2  can include at least a portion of the beam  303 - 2  emitted by the emitter  301 - 2 . Additionally, the field of view  311  of receiver lens  307  may include at least a portion of the beam  303 - 2 . 
     Secondary receiver lens  309 - 2  can have a field of view  313 - 2  which includes a region  321  between an edge  311 - 2  of the field of view  311  of the primary receiver lens  307  and the emitter  301 - 2 . This can allow additional smoke, such as smoke  317 - 2 , that is located outside the field of view  311  of the primary receiver lens  307  and the field of view  313 - 1  of the other secondary receiver lens  309 - 1  to be detected. 
       FIG.  4    illustrates another example apparatus  400  in accordance with one or more embodiments of the present disclosure. Apparatus  400  may include a light emitter  401  which is configured to emit a beam  403  and positioned vertically above or below a light receiver  405 . The beam  403  may illuminate smoke  417 . However, all of or a portion of the beam  403  may be outside of the field of view of the light receiver  405  (e.g., field of view  211  shown in  FIG.  2    and field of view  311  shown in  FIG.  3   ). As such, the light receiver may include a first receiver lens  407  and a second receiver lens  409 . The second receiver lens  409  may be positioned at an angle with respect to the primary receiver lens  407  such that the field of view  413  of the second receiver lens overlaps with portions of the beam  403  that do not overlap with the field of view of the first receiver lens  407 . 
       FIG.  5 A  is a top view of an area  518  including an apparatus in accordance with one or more embodiments of the present disclosure.  FIG.  5 B  is a top view of the area  518  including the apparatus for detecting smoke and an object in accordance with one or more embodiments of the present disclosure.  FIG.  5 C  is another top view of the area  518  including the apparatus for detecting smoke and an object in accordance with one or more embodiments of the present disclosure.  FIGS.  5 A,  5 B, and  5 C  may be cumulatively referred to as “ FIG.  5   .” 
     As shown in  FIG.  5   , the area  518  includes a plurality of walls: a north wall  518 - 1 , an east wall  518 - 2 , a south wall  518 - 3 , and a west wall  518 - 4 . It is noted that embodiments of the present disclosure are not limited to the layout or the shape of the area  518 . A smoke detecting apparatus  500 , which may be analogous to a number of the apparatuses previously described in  FIGS.  1 - 4   , is shown positioned in a corner of the area where the west wall  518 - 4  meets the south wall  518 - 3 . 
     As shown in  FIG.  5   , the apparatus  500  emits a beam  503  across the area  518 . In some embodiments, the beam is more than 7 millimeters in diameter. For instance, in some embodiments the beam exceeds 25 millimeters. The apparatus can emit the beam  503  at a first power level while the emitter rotates such that the beam  503  periodically scans across the area  518 . Scanning the area  518  with the beam  503  can include passing the beam  503  from the south wall  518 - 3 , along the east wall  518 - 2 , to the west wall  518 - 4 . A “scan” of the beam  503  can refer to a rotation of the emitter such that the beam begins at an initial angular position and ends at a terminal angular position. For example, a scan of the area  518  can include the beam moving from an angle substantially parallel to the south wall  518 - 3  (e.g., 0 degrees) to an angle substantially parallel to the west wall  518 - 4  (e.g., 90 degrees). A scan (e.g., a subsequent scan) can include the beam moving from an angle substantially parallel to the west wall  518 - 4  (e.g., 90 degrees) to an angle substantially parallel to the south wall  518 - 3  (e.g., 0 degrees). 
     The apparatus  500  can undergo a commissioning phase wherein the area  518  is scanned and the shape and nature of the area  518  is determined by the apparatus  500 . Any fixed objects in the area  518  may be mapped during this phase. 
     It should be appreciated that the location of the apparatus  500  in the area  518  dictates the nature of the scanning performed by the apparatus  500 . For example, an apparatus mounted on a straight wall, rather than in a corner, may scan a region of 180 degrees rather than 90 degrees. An apparatus hung from a ceiling may continually rotate, scanning 360 degrees. 
     The first power level, as described herein, is a “high” power level. In some embodiments, the first power level is between 30 and 50 Watts. In some embodiments, the first power level is between 35 and 45 Watts. In some embodiments, the first power level is between 39 Watts and 41 Watts. In some embodiments, the first power level is approximately 40 Watts. The first power level is a level at which the apparatus  500  can detect smoke in the area  518  in a manner as discussed above, for instance. The apparatus  500  can continue to periodically scan the area  518  for smoke at the first power level until an object enters a path of the beam  503  (e.g., as shown in  FIG.  5 B ). 
     As shown in  FIG.  5 B , an object  520  (e.g., a person) in the area has entered the path of the beam  503 . The presence of the object  520  can be determined using a receiver, as described herein. For instance, the receiver can be configured to measure the time taken for a pulse of light to travel from the emitter, reflect off the object  520  and travel back to the receiver. Embodiments herein can determine that the object  520  is in the path of the beam  503  and, responsive thereto, decrease the beam to a second power level. In some embodiments, the decrease in power is carried out in less than one microsecond. The second power level is a power level that is insufficient to cause damage to a human eye. In some embodiments, the second power level is between 5 and 15 watts. In some embodiments, the second power level is between 9 Watts and 11 Watts. In some embodiments, the second power level is approximately 10 Watts. 
     In the example illustrated in  FIG.  5 B , the apparatus  500 , while scanning northward, determines that the object  520  is in the path of the beam  503  while the emitter is at a first angular position  522 - 1  and reduces to the second power level. The apparatus  500  can continue to scan northward at the second power level until the object  520  is no longer in the path of the beam  503 , which it determines while the emitter is at a second angular position  522 - 2 . Responsive to the determination that the object  520  is no longer in the path of the beam  503 , the power level is increased back to the first power level and scanning continues at the first power level. The apparatus  500  can determine the first angular position  522 - 1  and the second angular position  522 - 2  using an angle measuring sensor, for instance, and store the first angular position  522 - 1  and the second angular position  522 - 2  in memory. 
     As shown in  FIG.  5 B , an angle between the first angular position  522 - 1  and the second angular position  522 - 2  defines a sector  524 . During another scan subsequent to the determination of the object  520  (in this example a southward scan), the apparatus  500  can operate at the first power level outside of the sector  524  and operate at the second power level inside of the sector  524 . Stated differently, embodiments herein can reduce power on subsequent scans preemptively (e.g., without redetermining the presence of the object  520 ). In some embodiments, such as the example discussed in connection with  FIG.  5 C , the size of the sector  524  can be increased to provide an additional measure of safety and/or allow for movement of the object  520 . 
     In some embodiments, this preemptive reduction in power can continue for a particular period of time. In some embodiments, this preemptive reduction in power can continue for a particular quantity of scans. In some embodiments, this preemptive reduction in power can continue until a determination is made that the object  520  is no longer in the path of the beam  503  when the emitter is between the first angular position  522 - 1  and the second angular position  522 - 2 . For example, in some embodiments, the second power level is sufficient to determine whether the object  520  is still in the path of the beam  503 . If the object  520  remains in the path of the beam  503  for a period of time exceeding a time threshold, some embodiments include providing a notification (e.g., an alarm). 
     In some embodiments, such as the example discussed in connection with  FIG.  5 C , the size of the sector can be increased to provide an additional measure of safety and/or allow for movement of the object  520 . Stated differently, the portion of the scan during which power is reduced to the second power level can be increased in size beyond the determined edges of the object. As shown in  FIG.  5 C , a third angular position  522 - 3  and a fourth angular position  522 - 4  define a second sector  526 . As shown, the second sector  526  can share a common centerline  528  with the sector  524 . The second sector  526  can be larger than the sector  524  by a particular amount and/or proportion. In some embodiments, for instance, the second sector  526  can be between 1% and 100% larger than the sector  524 . In some embodiments, the second sector  526  can be between 2 degrees and 10 degrees wider than the sector  524 . 
       FIG.  6    illustrates a method  630  for operating a scanning smoke detector in accordance with one or more embodiments of the present disclosure. The method  630  can include, at  632 , operating a laser emitter to emit a beam of light at a first power level while rotating the laser emitter such that the beam periodically scans across an area. The method  630  can include, at  634 , receiving a reflected portion of the beam of light using a light receiver configured to determine a presence of smoke particles in the area based on the reflected portion. 
     The method  630  can include, at  636 , decreasing the beam to a second power level responsive to determining that an object in the area is in a path of the beam when the emitter is at a first angular position. The method  630  can include, at  638 , increasing the beam to the first power level responsive to determining that the object is no longer in the path of the beam when the emitter is at a second angular position. 
     In some embodiments, the method  630  includes operating the laser emitter to emit the beam of light at the second power level between the first angular position and the second angular position for a particular period of time after determining that the object is no longer in the path of the beam when the emitter is at the second angular position. In some embodiments, the method  630  includes operating the laser emitter to emit the beam of light at the first power level responsive to determining that the object is no longer in the path of the beam when the emitter is between the first angular position and the second angular position. In some embodiments, the method  630  includes decreasing the beam to the second power level responsive to determining that the object or a different object in the area is in the path of the beam when the emitter is at a third angular position and increasing the beam to the first power level responsive to determining that the object or the different object is no longer in the path of the beam when the emitter is at a fourth angular position. 
     Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art will appreciate that any arrangement calculated to achieve the same techniques can be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments of the disclosure. 
     It is to be understood that the above description has been made in an illustrative fashion, and not a restrictive one. Combination of the above embodiments, and other embodiments not specifically described herein will be apparent to those of skill in the art upon reviewing the above description. 
     The scope of the various embodiments of the disclosure includes any other applications in which the above structures and methods are used. Therefore, the scope of various embodiments of the disclosure should be determined with reference to the appended claims, along with the full range of equivalents to which such claims are entitled. 
     In the foregoing Detailed Description, various features are grouped together in example embodiments illustrated in the figures for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the embodiments of the disclosure require more features than are expressly recited in each claim. 
     Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.