Patent Publication Number: US-2020300974-A1

Title: Compact chip scale lidar solution

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/248,948, filed on Jan. 16, 2019, which is a continuation of U.S. patent application Ser. No. 14/947,249, filed on Nov. 20, 2015, (now U.S. Pat. No. 10,215,846) the entirety of both are hereby incorporated herein by reference. 
    
    
     BACKGROUND 
     IDAR is a system that measures the distance to a target object by reflecting a laser pulse off of the target and analyzing the reflected light. More specifically, LIDAR systems typically determine a time of flight (TOF) for the laser pulse to travel from the laser to the target object and return. The distance to the target object then may be determined based on the TOF. These systems may be used in many applications including: geography, geology, geomorphology, seismology, transport, and remote sensing. For example, in transportation, automobiles may include LIDAR systems to monitor the distance between the vehicle and other objects (e.g., another vehicle). The vehicle may utilize the distance determined by the LIDAR system to, for example, determine whether the other object, such as another vehicle, is too close, and automatically apply braking. Conventional LIDAR systems may require multi-chip solutions in which the driver circuitry for the laser and the timing circuitry to determine the TOF are separate circuits. 
     SUMMARY 
     The problems noted above are solved in large part by systems and methods for determining distances to target objects utilizing a monolithic LIDAR transceiver. In some embodiments, a LIDAR system includes a static monolithic LIDAR transceiver, a collimating optic, and a first rotatable wedge prism. The static monolithic LIDAR transceiver is configured to transmit a laser beam and receive reflected laser light from a first target object. The collimating optic is configured to narrow the transmitted laser beam to produce a collimated laser beam. The first rotatable wedge prism is configured to steer the collimated laser beam in a direction of the first target object based on the first rotatable wedge prism being in a first position. 
     Another illustrative embodiment is a method that comprises transmitting, by a monolithic LIDAR transceiver, a laser beam in a first direction. The method may also comprise refracting, by a first wedge prism in a first position and a second wedge prism in a second position, the laser beam in a second direction. The method may also comprise reflecting the laser beam off of a first target object to produce a first reflected light beam in a direction opposite the second direction. The method may also comprise refracting, by the first wedge prism and the second wedge prism the first reflected light beam in a direction opposite the first direction. The method may also comprise receiving, by the monolithic LIDAR transceiver, the first reflected light beam. 
     Yet another illustrative embodiment is a monolithic LIDAR transceiver comprising a laser and a photodiode coupled to the laser in a single integrated circuit. The laser is configured to generate a laser beam and transmit the laser beam in a first direction to a first rotatable wedge prism and a second rotatable wedge prism. The first and second rotatable wedge prisms are configured to steer the laser beam in a second direction. The photodiode is configured to receive a first reflected light beam. The first reflected light beam comprises the laser beam reflected off of a first target object in a direction opposite the second direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a detailed description of various examples, reference will now be made to the accompanying drawings in which: 
         FIG. 1  shows a block diagram of a system for determining distances to a target object in accordance with various embodiments; 
         FIG. 2  shows a block diagram of a LIDAR system in accordance with various embodiments; 
         FIG. 3  shows a block diagram of a LIDAR system in accordance with various embodiments; 
         FIG. 4  shows a monolithic LIDAR transceiver in accordance with various embodiments; 
         FIG. 5  shows a flow diagram of a method for determining distances to target objects in accordance with various embodiments; and 
         FIG. 6  shows a flow diagram of a method for determining distances to target objects in accordance with various embodiments. 
     
    
    
     NOTATION AND NOMENCLATURE 
     Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices and connections. The recitation “based on” is intended to mean “based at least in part on.” Therefore, if Xis based on Y, X may be based on Y and any number of other factors. 
     DETAILED DESCRIPTION 
     The following discussion is directed to various embodiments of the invention. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment. 
     LIDAR systems may determine distances to various target objects utilizing the time of flight (TOF) of a laser pulse (i.e., drive pulse) to the target object and its reflection off a target object back to the LIDAR system (return pulse). These systems may be used in many applications including: geography, geology, geomorphology, seismology, transport, and remote sensing. For example, in transportation, automobiles may include LIDAR systems to monitor the distance between the vehicle and other objects (e.g., another vehicle). The vehicle may utilize the distance determined by the LIDAR system to, for example, determine whether the other object, such as another vehicle, is too close, and automatically apply braking. 
     In a conventional LIDAR system, a photodiode receives the return pulse (i.e., the reflected laser light from the target object) and converts the photons in the return pulse to a current. This current then is utilized by timing circuitry to determine TOF. Additional processing then may allow the LIDAR system to determine the distance to the target object. Because the photodiode that receives the return pulse requires a large gain so that the timing circuitry can identify the TOF, conventional LIDAR systems utilize multi-chip solutions in which the driver circuitry for the laser and the photodiode, and its associated timing circuitry, are separate circuits. However, a multi-chip solution is less efficient than a single chip solution. Thus, it is desirable to produce a photodiode that is integrated into a single integrated circuit with the driver circuitry and laser so as to efficiently determine distance to target objects utilizing LIDAR. 
     A monolithic LIDAR transceiver may include a photodiode that is integrated with the driver circuitry and laser. The monolithic LIDAR transceiver may be coupled to a series of wedge prisms to steer the laser pulse (laser beam) to target objects. This system allows the photodiode to generate a sufficient gain such that the timing circuitry may accurately time the return pulse. Therefore, the LIDAR transceiver may be a single integrated circuit producing greater efficiencies than a multi-chip LIDAR solution. 
       FIG. 1  shows a block diagram of a system  100  for determining distances to a target object in accordance with various embodiments. The system  100  for determining distances to a target object may include a LIDAR system  102  and target objects  104   a - n.  The ellipsis between the target objects  104   a  and  104   n  indicates that there may be any number of target objects  104 , although, for clarity, only two are shown. In some embodiments, the LIDAR system  104  is configured to be mounted to an automobile, such as on and/or in the front and/or rear bumper of the automobile, on the roof of the automobile, and/or on the side of the automobile. In other embodiments, the LIDAR system  104  may be mounted in any location on an automobile or any other object. 
     The LIDAR system  104  is configured to generate and transmit a laser beam  106  (i.e., a drive pulse) and steer (i.e., direct) the laser beam  106  to a target object, such as target object  104   a.  In some embodiments, the laser beam  106  is a relatively short light pulse. The laser beam  106  reflects off of target object  104   a  as reflected laser light beam  108  (i.e., a return pulse). The reflected laser light beam  108  is received by LIDAR system  102 . The LIDAR system  102  then may be configured to identify the distance from the LIDAR system  102  to the target object  104   a  based on a time of flight (TOF) of the laser beam  106  and reflected laser light beam  108 . More specifically, the LIDAR system  102  may determine the time between the transmission of the laser beam  106  and the receipt by the LIDAR system  102  of the reflected laser light beam  108  (i.e., the TOF). Utilizing this elapsed time and knowing the speed of light, the LIDAR system  102  may calculate and identify the distance to the target object  104   a.    
     In a similar way, the LIDAR system  102  may determine the distance to any number of other target objects  104 . For example, LIDAR system  102  may generate a second laser beam  110  (i.e., a second drive pulse) and steer the laser beam  106  to target object  104   n.  The laser beam  110  reflects off of target object  104   n  as reflected laser light beam  112  (i.e., a second return pulse). The reflected laser light beam  112  is received by LIDAR system  102 . The LIDAR system  102  then may calculate and identify the distance from the LIDAR system  102  to the target object  104   n  based, in some embodiments, on the TOF of the laser beam  110  and the reflected laser light beam  112 . 
       FIG. 2  shows a block diagram of LIDAR system  102  in accordance with various embodiments. In an embodiment, LIDAR system  102  includes monolithic transceiver  202 , collimating optic  204 , rotatable wedge prisms  206  and  208 , motors  210  and  212 , controller  214 , data port/power connection  216 , and housing  218 . Monolithic transceiver  202  is configured to transmit a laser beam, such as laser beam  106 , and receive reflected laser light, such as reflected laser light beam  108 , from a target object, such as target object  104   a.  In some embodiments, the monolithic transceiver  202  is static. In other words, the monolithic transceiver  202  may be configured such that it does not move in relation to other components of the LIDAR system  102 . Therefore, while the monolithic transceiver  202  may move along with, for example, an automobile that the LIDAR system  102  is mounted, the monolithic transceiver  202  may not move in relation to the collimating optic  204 , the motors  210  and  212  and the housing  218 . Thus, the monolithic transceiver  202  may always transmit laser beams, such as laser beam  106  and  110 , in the same direction relative to the collimating optic  204  and housing  218 . 
     Collimating optic  204  is an optic that is configured to narrow the transmitted laser beam, such as laser beam  106 , to produce a collimated laser beam. In other words, the collimating optic  204  is configured to cause the direction of motion of the particles of the transmitted laser beam to become more aligned in the direction of the transmission by monolithic transceiver  202 . Thus, the collimated laser beam is the transmitted laser beam with parallel rays. 
     The collimated laser beam (i.e., the transmitted laser beam with parallel rays) then may pass through wedge prisms  206  and  208 . The wedge prisms  206  and  208  are rotatable and configured to steer, by refracting, the collimated laser beam in the direction of a first target object, such as target object  104   a.  The wedge prisms  206  and  208  may work as a Risley prism pair. In other words, by rotating wedge prism  206  in relation to wedge prism  208 , the collimated laser beam may be steered due to the refraction of the collimated laser beam when it passes through the wedge prisms  206  and  208 . For example, if wedge prism  206  is angled in the same direction as wedge prism  208 , the angle of refraction becomes larger; however, if wedge prism  206  is angled in an opposite direction from wedge prism  208 , then the angle of refraction is reduced, in some cases to the point where the collimated laser beam passes straight through the wedge prisms  206  and  208 . Thus, by rotating the wedge prisms  206  and  208 , the collimated laser beam may be steered. 
     Motor  210  is coupled to wedge prism  206  and may be configured to rotate the wedge prism  206 . Motor  212  is coupled to wedge prism  208  and may be configured to rotate the wedge prism  208 . Motors  210  and  212  may be any type of motor that is capable of rotating the wedge prisms  206  and  208 . In some embodiments, motors  210  and  212  are servomotors. In other embodiments, the motors  210  and  212  are stepper motors or any other type of electric motor. Controller  214  is coupled to motors  210  and  212  and may act to provide control signals to the motors  210  and  212 . Controller  214  may receive control instructions, in some embodiments, from a processor outside of LIDAR system  102  through data port/power connection  216 . The control instructions then may act to control the motors  210  and  214  so that the wedge prisms  206  and  208  are positioned to steer the collimated laser beam to the target object  104 . For example, the control instructions may cause controller  214  to send a control signal to motors  210  and  212  to rotate the wedge prisms  206  and  208  to a position such that the target object  104  is illuminated by the collimated laser beam. Housing  218  may be a rigid casing that encloses and protects the remaining components of LIDAR system  102 . In the embodiment depicted in  FIG. 2 , the housing  218  has an opening in line with the direction of the transmission of laser beam  106  plus or minus 30 degrees. Thus, the laser beam  106  may be steered in any direction that is within 30 degrees of the direction of the transmitted laser beam  106 . 
     For example, the LIDAR system  102  may be configured to scan directly in front of a moving automobile plus or minus 30 degrees for objects and determine the distance to any object within plus or minus 30 degrees of the direction the automobile is facing. In this example, controller  214  may receive control instructions that instruct the motors  210  and  212  to rotate the wedge prisms  206  and  208 . The monolithic LIDAR transceiver  202  may transmit a laser beam  106  (i.e., drive pulse) through the collimating optic  204  in a first direction and the wedge prisms  206  and  208 . Due to the relative positions (in terms of rotation) of the wedge prisms  206  and  208 , the laser beam  106  (as a collimated laser beam) is refracted. Thus, wedge prism  206  may be in a first position while wedge prism  208  is in a second position. This causes the wedge prisms  206  and  208  to steer the laser beam  106  in a second direction. Once the laser beam  106  reaches target object  104   a,  reflected laser light beam  108  (i.e., return pulse) returns in a direction opposite (i.e., 180 degrees from) the second direction (i.e., the direction opposite the direction the laser beam  106  was travelling immediately after being refracted by wedge prisms  206  and  208 ) to the LIDAR system  102 . The wedge prisms  206  and  208 , maintaining their positions, then act to refract the reflected laser light beam  108  in a direction opposite (i.e., 180 degrees from) the first direction (i.e., the direction opposite the direction laser beam  106  travelled when transmitted). Thus, the wedge prisms  206  and  208  act as both the transmission and return path of the laser beam  106  and reflected laser light beam  108 . This causes the reflected laser light beam  108  to be received by the monolithic transceiver  202 . The monolithic transceiver  202  then may identify the distance to the target object  104   a based on the TOF.    
       FIG. 3  shows a block diagram of LIDAR system  102  in accordance with various embodiments. In this embodiment, LIDAR system  102  includes monolithic transceiver  202 , collimating optic  204 , rotatable wedge prisms  206  and  208 , motors  210  and  212 , controller  214 , data port/power connection  216 , housing  318  and cone mirror  320 . Therefore, the LIDAR system depicted in  FIG. 3  is the same as the LIDAR system depicted in  FIG. 2  except for housing  318  and the addition of cone mirror  320 . Housing  318  may be a rigid casing that encloses and protects the remaining components of LIDAR system  102 . In the embodiment depicted in  FIG. 3 , the housing  318  has an opening at a right angle with the direction of the transmission of laser beam  106  plus or minus 30 degrees. Cone mirror  320  may be any mirror that is in the shape of a cone that is configured to reflect a laser beam, such as laser beam  106 , in some embodiments, in a direction at a right angle plus or minus 30 degrees from the direction of transmission of the laser beam  106 . 
     For example, the LIDAR system  102  may be configured to scan a 360 degree panorama around a moving automobile and determine the distance to any object within the panorama. In this example, controller  214  may receive control instructions that instruct the motors  210  and  212  to rotate the wedge prisms  206  and  208 . The monolithic LIDAR transceiver  202 , which in this example may be directed directly up, may transmit a laser beam  106  (i.e., drive pulse) through the collimating optic  204  in a first direction and the wedge prisms  206  and  208 . Due to the relative positions (in terms of rotation) of the wedge prisms  206  and  208 , the laser beam  106  (as a collimated laser beam) is refracted. Thus, wedge prism  206  may be in a first position while wedge prism  208  is in a second position. This causes the wedge prisms  206  and  208  to steer the laser beam  106  in a second direction. The laser beam  106  then may reflect off of the cone mirror  320  in the direction of target  104   a.  The reflection off the cone mirror  320  may cause the laser beam  106  to travel in a third direction, a direction at a right angle plus or minus thirty degrees from the first direction (i.e., the direction laser beam  106  travelled when transmitted). In this example, because the laser beam  106  is transmitted directly up by the monolithic transceiver  202 , the laser is reflected by the cone mirror  320  approximately horizontal (parallel to the roof of the automobile) plus or minus 30 degrees. Once the laser beam  106  reaches target object  104   a,  reflected laser light beam  108  (i.e., return pulse) returns in a direction opposite (i.e., 180 degrees from) the third direction (i.e., the direction opposite the direction the laser beam  106  was travelling immediately after being reflected off of cone mirror  320 ) to the LIDAR system  102 . The reflected laser light beam  108  then reflects off the cone mirror  329  in a direction directly opposite (i.e., 180 degrees from) the second direction (i.e., the direction opposite the direction the laser beam  106  was travelling immediately after being refracted by wedge prisms  206  and  208 ). The wedge prisms  206  and  208 , maintaining their positions then act to refract the reflected laser light beam  108  in a direction opposite (i.e., 180 degrees from) the first direction (i.e., the direction opposite the direction laser beam  106  travelled when transmitted). Thus, the wedge prisms  206  and  208  and cone mirror  320  act as both the transmission and return path of the laser beam  106  and reflected laser light beam  108 . This causes the reflected laser light beam  108  to be received by the monolithic transceiver  202 . The monolithic transceiver  202  then may identify the distance to the target object  104   a  based on the TOF. Thus, the laser beam  106  may be steered in any direction that is within 30 degrees of a right angle of the direction of the transmitted laser beam  106 . This allows for a 360 degree scan by the LIDAR system  102  mapping the distance to various target objects within the field of the scan. 
       FIG. 4  shows monolithic LIDAR transceiver  202  in accordance with various embodiments. Monolithic LIDAR transceiver  202  may comprise a laser  402 , a photodetector circuit/pulse shifter circuit  404 , a coincidence timing circuit  406 , a timing circuit  408 , a processing circuit  410 , and a bias/pulse driver circuit  412  in a single integrated circuit. Laser  402  may be any device that emits light through amplification based on stimulated emission of radiation. In some embodiments, laser  402  is any type of laser diode. More particularly, in an embodiment, the laser  402  is a vertical-cavity surface-emitting laser (VCSEL) operating in pulse mode while in other embodiments, the laser  402  is a double heterostructure laser, a quantum well laser, a quantum cascade laser, a separate confinement heterostructure laser, a distributed Bragg reflector laser (DBR), a distributed feedback laser (DFB), or a vertical-external-cavity surface-emitting laser (VECSEL). Laser  402  may operate at any operating power, and in some embodiments, operates at 2-5 mW. The bias/pulse driver circuit  412  is hardware that causes forward electrical bias across the laser  402  to power the laser  402 . Additionally, the bias/pulse driver circuit  412  may be configured to set the pulse width of the laser beam  106 ,  110  generated by laser  402 . In some embodiments, the pulse width of the laser beams  106  and  110  is less than 30 ns. Thus, the bias/pulse driver circuit  412  may cause the laser  402  to transmit laser beams  106  and  110 , each with a pulse duration of less than 30 ns. 
     The photodetector circuit/pulse shaper  404  may include a photodiode  414  that is configured to absorb photons received from the reflected laser light beams  108  and  112  into current to be processed by other components of the monolithic LIDAR transceiver  202 . In some embodiments, the photodiode  414  is an avalanche photodiode (APD). Photodetector circuit/pulse shaper  404  may also be configured to pulse shape the transmitted laser beam  106 , 110  and/or the received reflected laser light beams  108  and  112 . Coincidence timing circuit  406  includes hardware that determines coincidence timing of the received reflected laser light beams  108  and  112 . Timing circuit  408  includes hardware that determines the TOF of the laser light beams  106  and  110  and their corresponding reflected laser light beams  108  and  112 . Processing circuit  410  is configured to determine the distance to the target object  104  based on the TOF determined by timing circuit  408 . Processing circuit  410  may be any type of processor including a digital signal processor. 
       FIG. 5  shows a flow diagram of a method  500  for determining distances to target objects, such as target objects  104 , in accordance with various embodiments.  FIG. 6  shows a flow diagram of a method  600  for determining distances to target objects, such as target objects  104 , in accordance with various embodiments. Though depicted sequentially as a matter of convenience, at least some of the actions shown in methods  500  and  600  can be performed in a different order and/or performed in parallel. Additionally, some embodiments may perform only some of the actions shown or may perform additional actions. In some embodiments, at least some of the operations of the methods  500  and  600 , as well as other operations described herein, can be performed by LIDAR system  102 , including monolithic transceiver  202 , collimating optic  204 , controller  214 , wedge prisms  206  and  208 , motors  210  and  212 , and/or cone mirror  320 , implemented by a processor executing instructions stored in a non-transitory computer readable storage medium or a state machine. 
     The method  500  begins in block  502  with transmitting a first laser beam, such as laser beam  106 , in a first direction utilizing a monolithic LIDAR transceiver, such as monolithic LIDAR transceiver  202 . In block  504 , the method  500  continues with refracting the transmitted first laser beam in a second direction utilizing two wedge prisms, such as wedge prisms  206  and  208 . In an embodiment, the rotational position of the two wedge prisms with respect to one another determines the direction of the refraction. In some embodiments, the laser beam may be refracted by the two wedge prisms in any direction that is within 30 degrees of the direction of the transmitted laser beam. The method  500  continues in block  506  with reflecting the transmitted laser beam off a first target object, such as target object  104   a,  producing a reflected laser light beam, such as first reflected laser light beam  108 . The first reflected laser light beam may travel in a direction opposite the second direction (i.e., 180 degrees from the direction of travel of the first laser beam immediately prior to reflecting off of the first target object). In block  508 , the method  500  continues with refracting the reflected light beam in a direction opposite the first direction utilizing the two wedge prisms (i.e., 180 degrees from the direction of travel of the first laser beam as transmitted by the monolithic LIDAR transceiver). The method  500  continues in block  510  with receiving the first reflected laser light beam by the monolithic LIDAR transceiver. In block  512 , the method  500  continues with identifying the distance to the first target object. In some embodiments, the distance to the first target object may be identified based on the amount of time between the transmitting of the first laser beam by the monolithic LIDAR transceiver and the receiving of the first reflected laser light beam by the monolithic LIDAR transceiver (i.e., the TOF). 
     The method  500  continues in block  514  with rotating both of the wedge prisms. In an embodiment, one or more motors, such as motors  210  and  212  may rotate the two wedge prisms in response to a control signal received from controller  214 . In block  516 , the method  500  continues with refracting a second laser beam, such as laser beam  110  in a third direction utilizing the two wedge prisms. The second laser beam may be transmitted by the monolithic LIDAR transceiver in the same direction relative to the two wedge prisms as the first laser beam. In an embodiment, the rotational position of the two wedge prisms with respect to one another determines the direction of the refraction. In some embodiments, the second laser beam may be refracted by the two wedge prisms in any direction that is within 30 degrees of the direction of the transmitted second laser beam. The method  500  continues in block  518  with reflecting the second laser beam off a second target object, such as target object  104   n,  which produces a second reflected laser light beam, such as reflected laser light beam  112 . The second reflected laser light beam may travel in a direction opposite the third direction (i.e., 180 degrees from the direction of travel of the second laser beam immediately prior to reflecting off of the second target object). In block  520 , the method  500  continues with refracting the second reflected light beam in a direction opposite the first direction utilizing the two wedge prisms (i.e., 180 degrees from the direction of travel of the second laser beam as transmitted by the monolithic LIDAR transceiver). The method  500  continues in block  522  with receiving the second reflected laser light beam by the monolithic LIDAR transceiver. In block  524 , the method  500  continues with identifying the distance to the second target object. In some embodiments, the distance to the second target object may be identified based on the amount of time between the transmitting of the second laser beam by the monolithic LIDAR transceiver and the receiving of the second reflected laser light beam by the monolithic LIDAR transceiver (i.e., the TOF). 
       FIG. 6  shows a flow diagram of a method  600  for determining distances to target objects, such as target objects  104 , in accordance with various embodiments. The method  600  begins in block  602  with transmitting a laser beam, such as laser beam  106 , in a first direction utilizing a monolithic LIDAR transceiver, such as monolithic LIDAR transceiver  202 . In block  604 , the method  600  continues with refracting the transmitted laser beam in a second direction utilizing two wedge prisms, such as wedge prisms  206  and  208 . In an embodiment, the rotational position of the two wedge prisms with respect to one another determines the direction of the refraction. In some embodiments, the laser beam may be refracted by the two wedge prisms in any direction that is within 30 degrees of the direction of the transmitted laser beam. The method  600  continues in block  606  with reflecting the laser beam in a third direction utilizing a cone mirror, such as cone mirror  320 . In some embodiments, the cone mirror may reflect the laser beam in a direction at a right angle plus or minus 30 degrees from the direction of transmission of the laser beam. In block  608 , the method continues with reflecting the transmitted laser beam off a target object, such as target object  104   a,  producing a reflected laser light beam, such as reflected laser light beam  108 . The reflected laser light beam may travel in a direction opposite the third direction (i.e., 180 degrees from the direction of travel of the laser beam immediately prior to reflecting off of the first target object). The method continues in block  610  with reflecting the reflected laser light beam off the cone mirror in a direction opposite the second direction (i.e., 180 degrees from the direction of travel of the laser beam immediately after being refracted by the two wedge prisms). In block  612 , the method  600  continues with refracting the reflected light beam in a direction opposite the first direction utilizing the two wedge prisms (i.e., 180 degrees from the direction of travel of the laser beam as transmitted by the monolithic LIDAR transceiver). The method  600  continues in block  614  with receiving the reflected laser light beam by the monolithic LIDAR transceiver. In block  616 , the method  600  continues with identifying the distance to the first target object. In some embodiments, the distance to the first target object may be identified based on the amount of time between the transmitting of the laser beam by the monolithic LIDAR transceiver and the receiving of the reflected laser light beam by the monolithic LIDAR transceiver (i.e., the TOF). 
     The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.