EXHIBIT C 

Case 3:17-cv-00939-WHA Document 1-3 Filed 02/23/17 Page 1 of 14
US009086273B1 

(12) United States Patent (10) Patent No.: US 9,086,273 B1 

Gruver et al. (45) Date of Patent: Jul. 21, 2015 

(54) MICROROD COMPRESSION OF LASER o 52- . ~ * }. o ; i. egnan BEAM IN COMBINATION WITH TRANSMIT 7,255,275 B2 8/2007 Gurevich et al. 

LENS 7,688,348 B2 3/2010 Lubard et al. 

7,701,558 B2 4/2010 Walsh et al. 

(71) Applicant: Google Inc., Mountain View, CA (US) 7,710,545 B2 5/2010 Cramblitt et al. 

7,969,558 B2 6/2011 Hall - e - 2005/0237519 A1 * 10/2005 Bondurant et al. ........ 356/241.1 

(72) Inventors: Daniel Gruver, San Francisco, CA 2007/02684.74 A1 :}; 1 1/2007 Omura et al. ------------------- 355/67 

(US); Pierre-Yves Droz. Mountain 2008/0100820 A1* 5/2008 Sesko ......... ... 356/4.01 View, CA (US); Gaetan Pennecot, San 2009/0059183 A1* 3/2009 Tejima ............................ 353/69 

Francisco, CA (US); Zachary Morriss, 2009/01472.39 A1 6/2009 Zhu et al. 

San Francisco, s CA (US); s Dorel Ionut !o. 2011/0216304 A1 A 3: 9/2011 Ha osal or 356/338 

Iordache, Walnut Creek, CA (US) 2011/0255070 A1* 10/2011 Phillips et al. ............... 356/4.01 

2013/0114077 A1* 5/2013 Zhang ........................... 356/328 (73) Assignee: Google Inc., Mountain View, CA (US) OTHER PUBLICATIONS 

(*) Notice: Subj ect to any o the o: OSRAM Opto Semiconductors GmbH, Datasheet for SPL DL90 3 

o o: e 20. adjusted under Nanostack Pulsed Laser Diode, Mar. 24, 2009. -- - *--> - y ays. 

* cited by examiner 

(21) Appl. No.: 13/790,251 y 

- Primary Examiner – Isam Alsomiri 

(22) Filed: Mar. 8, 2013 Assistant Examiner – Samantha KAbraham 

(51) Int. Cl (74) Attorney, Agent, or Firm — McDonnell Boehnen 

Goic 30s (2006.01) Hulbert & Berghoff LLP 

G0IC 3/02 2006.01 (52) U.S. Cl ( ) (57) ABSTRACT 

Croo. Goic 3/02 (2013.01) A LIDAR device may transmit light pulses originating from 

(58) Field of Classification Search one or more light sources and may receive reflected light 

CPC G01S 17/10: G01S 7/497: G01S 17/89: pulses that are detected by one or more detectors. The LIDAR - - - - - - - - - Gois 7487. Goid 308 device may include a lens that both (i) collimates the light 

USPC ......... 356,301,401,407, soil sojo,62s o the one or o lightsourcesto o o light S lication file f let h history. Or TrainSIII.1SS1011 1DIO all enviro?lineIII OT IIle eV1Ce 

ee application IIIe Ior complete searcn n1story and (ii) focuses the reflected light onto the one or more detec 

(56) References Cited tors. Each light source may include a respective laser diode 

|U.S. PATENT DOCUMENTS 

3,790,277 A 2/1974 Hogan 

4,700,301 A 10/1987 Dyke 

4,709,195 A 11/1987 Hellekson et al. 

4,801.201 A 1/1989 Eichweber 

5,202,742 A 4/1993 Frank et al. 

6,108,094 A * 8/2000 Tani et al. ..................... 356/417 

and cylindrical lens. The laser diode may emit an uncolli 

mated laserbeam that diverges more in a first direction than in 

a second direction. The cylindrical lens may pre-collimate the 

uncollimated laser beam in the first direction to provide a 

partially collimated laser that diverges more in the second 

direction than in the first direction. 

20 Claims, 6 Drawing Sheets 

100 

 

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VI. ?un61-I 

 

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U.S. Patent US 9,086,273 B1 

 

 

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U.S. Patent 

FIG. 2A 

FIG. 2C 

Jul. 21, 2015 Sheet 3 of 6 US 9,086,273 B1 

2– 

210 

206 } 208 

210 

212 

<– 200 

<!— 200 

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400 

Figure 4 

 

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U.S. Patent Jul. 21, 2015 Sheet 6 of 6 US 9,086,273 B1 

602 Emit an uncollimated laser beam from a laser diode, 

in which the uncollimated laser beam has a first 

divergence in a first direction and a second divergence 

in a second direction, with the first divergence being 

greater than the second divergence 

Pre-Collimate the uncollimated laser beam in the first 

direction to provide a partially collimated laser beam that 

has a third divergence in the first direction and a fourth 

divergence in the second direction, with the third divergence 

being less than the fourth divergence and fourth divergence 

being substantially equal to the second divergence 

604 

606 

Collimate, by a lens, the partially collimated laser beam 

to provide a collimated laser beam 

608 

Transmit the Collimated laser beam into an environment 

610 

Collect object-reflected light, in which the object-reflected 

light includes light from the collimated laser beam that has 

reflected from one or more objects in the environment 

612 

Focus, by the lens, the object-reflected light through a 

focusing path onto a detector 

Figure 6 

 

 

 

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US 9,086,273 B1 

1 

MICROROD COMPRESSION OF LASER 

BEAM IN COMBINATION WITH TRANSMIT 

LENS 

BACKGROUND 

Unless otherwise indicated herein, the materials described 

in this section are not prior art to the claims in this application 

and are not admitted to be prior art by inclusion in this section. 

Vehicles can be configured to operate in an autonomous 

mode in which the vehicle navigates through an environment 

with little or no input from a driver. Such autonomous 

vehicles can include one or more sensors that are configured 

to detect information about the environment in which the 

vehicle operates. The vehicle and its associated computer 

implemented controller use the detected information to navi 

gate through the environment. For example, if the sensor(s) 

detect that the vehicle is approaching an obstacle, as deter 

mined by the computer-implemented controller, the control 

ler adjusts the vehicle’s directional controls to cause the 

vehicle to navigate around the obstacle. 

One such sensor is a light detection and ranging (LIDAR) 

device. A LIDAR actively estimates distances to environmen 

tal features while scanning through a scene to assembly a 

cloud of point positions indicative of the three-dimensional 

shape of the environmental scene. Individual points are mea 

sured by generating a laser pulse and detecting a returning 

pulse, if any, reflected from an environmental object, and 

determining the distance to the reflective object according to 

the time delay between the emitted pulse and the reception of 

the reflected pulse. The laser, or set of lasers, can be rapidly 

and repeatedly scanned across a scene to provide continuous 

real-time information on distances to reflective objects in the 

scene. Combining the measured distances and the orientation 

of the laser(s) while measuring each distance allows for asso 

ciating a three-dimensional position with each returning 

pulse. A three-dimensional map of points of reflective fea 

tures is generated based on the returning pulses for the entire 

scanning zone. The three-dimensional point map thereby 

indicates positions of reflective objects in the scanned scene. 

SUMMARY 

A LIDAR device may transmit light pulses originating 

from one or more light sources and may receive reflected light 

pulses that are detected by one or more detectors. The LIDAR 

device may include a lens that both collimates the light from 

the one or more light sources and focuses the reflected light 

onto one or more detectors. Each light source may include a 

laser diode that emits an uncollimated laser beam that 

diverges more in a first direction than in a second direction 

and a cylindrical lens that pre-collimates the uncollimated 

laser beam in the first direction to provide a partially colli 

mated laser beam. 

In a first aspect, example embodiments provide a LIDAR 

device that includes at least one laser diode, at least one 

cylindrical lens, at least one detector, and an objective lens. 

The at least one laser diode is configured to emit an uncolli 

mated laser beam that includes light in a narrow wavelength 

range. The uncollimated laser beam has a first divergence in a 

first direction and a second divergence in a second direction. 

The first divergence is greater than the second divergence. 

The at least one cylindrical lens is configured to pre-collimate 

the uncollimated laser beam in the first direction to provide a 

partially collimated laser beam that has a third divergence in 

the first direction and a fourth divergence in the second direc 

tion. The third divergence is less than the fourth divergence, 

10 

15 

20 

25 

30 

35 

40 

45 

50 

55 

60 

65 

2 

and the fourth divergence is substantially equal to the second 

divergence. The at least one detector is configured to detect 

light having wavelengths in the narrow wavelength range. 

The objective lens is configured to (i) collimate the partially 

collimated laser beam to provide a collimated laser beam for 

transmission into an environment of the LIDAR device and 

(ii) focus object-reflected light onto the at least one detector. 

The object-reflected light includes light from the collimated 

laser beam that has reflected from one or more objects in the 

environment of the LIDAR device. 

In a second aspect, example embodiments provide a 

LIDAR device that includes a plurality of light sources, in 

which each light source is configured to emit partially colli 

mated light, a plurality of detectors, in which each detector is 

associated with a respective light source in the plurality of 

light sources, a lens, and a mirror. The lens is configured to (i) 

collimate the partially collimated light from the light sources 

to provide collimated light for transmission into an environ 

ment of the LIDAR device and (ii) focus onto each detector 

any object-reflected light from the detector’s associated light 

source that has reflected from one or more objects in the 

environment of the LIDAR device. The mirror is configured 

to rotate about an axis and, while rotating, reflect the colli 

mated light from the lens into the environment and reflect any object-reflected light from the environment into the lens. 

In a third aspect, example embodiments provide a method. 

The method involves emitting an uncollimated laser beam 

from a laser diode. The uncollimated laser beam has a first 

divergence in a first direction and a second divergence in a 

second direction. The first divergence is greater than the sec 

ond divergence. The method further involves pre-collimating 

the laser beam in the first direction to provide a partially 

collimated laser beam. The partially collimated laser beam 

has a third divergence in the first direction and a fourth diver 

gence in the second direction. The third divergence is less 

than the fourth divergence, and the fourth divergence is sub 

stantially equal to the second divergence. The method also 

involves collimating, by a lens, the partially collimated laser 

beam to provide a collimated laser beam and transmitting the 

collimated laser beam into an environment. In addition, the 

method involves collecting object-reflected light and focus 

ing, by the lens, the object-reflected light through a focusing 

path onto a detector. The object-reflected light includes light 

from the collimated laser beam that has reflected from one or 

more objects in the environment. 

In a fourth aspect, exemplary embodiments provide a 

LIDAR device that includes means for transmitting an uncol 

limating laser beam that has a first divergence in a first direc 

tion and a second divergence in a second direction, in which 

the first divergence is greater than the second divergence. The 

LIDAR device further includes means for pre-collimating the 

uncollimated laser beam in the first direction to provide a 

partially collimated laser beam that has a third divergence in 

the first direction and a fourth divergence in the second direc 

tion, in which he third divergence is less than the fourth 

divergence and the fourth divergence is substantially equal to 

the second divergence. In addition, the LIDAR device 

includes means for collimating the partially collimated laser 

beam, means for transmitting the partially collimated laser 

beam into an environment of the LIDAR device, means for 

collecting object-reflected light that includes light from the 

collimated laser beam that has reflected from one or more 

objects in the environment, and means for focusing the 

object-reflected light onto a detector. 

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3 

BRIEF DESCRIPTION OF THE DRAWINGS 

FIG. 1A is a top schematic view of a LIDAR device, in 

accordance with an example embodiment. 

FIG. 1B is a side schematic view of a portion of the LIDAR 

device of FIG. 1A, in accordance with an example embodi 

ment. 

FIG. 1C is a front schematic view of a portion of the 

LIDAR device of FIG. 1A, in accordance with an example embodiment. 

FIG. 2A is a view of a laser diode, in accordance with an 

example embodiment. 

FIG. 2B is a view of the laser diode of FIG. 2A in combi 

nation with a cylindrical lens, in accordance with an example 

embodiment. 

FIG. 2C is another view of the laser diode and cylindrical 

lens combination of FIG. 2B, in accordance with an example 

embodiment. 

FIG. 3 is schematic diagram of the LIDAR device of FIG. 

1A transmitting a collimated laser beam, in accordance with 

an example embodiment. 

FIG. 4 is a view of an aperture of a lens in the LIDAR 

device of FIG. 1A, in accordance with an example embodi 

ment. 

FIG. 5A illustrates a scenario in which LIDAR device 

scanning an environment that includes two objects, in accor 

dance with an example embodiment. 

FIG. 5B illustrates a point cloud for the two objects 

scanned in the scenario illustrated in FIG. 5A, in accordance 

with an example embodiment. 

FIG. 6 is a flow chart of a method, in accordance with an 

example embodiment. 

DETAILED DESCRIPTION 

A LIDAR device may transmit light pulses originating 

from one or more light sources and may receive reflected light 

pulses that are detected by one or more detectors. The LIDAR 

device may include a transmit/receive lens that both colli 

mates the light from the one or more light sources and focuses 

the reflected light onto the one or more detectors. By using a 

transmit/receive lens that performs both of these functions, 

instead of a transmit lens for collimating and a receive lens for 

focusing, advantages with respect to size, cost, and/or com 

plexity can be provided. 

Each light source may include a respective laser diode and 

cylindrical lens. The laser diode may emit an uncollimated 

laser beam that diverges more in a first direction than in a 

second direction. The cylindrical lens may pre-collimate the 

uncollimated laser beam in the first direction to provide a 

partially collimated laser beam, thereby reducing the diver 

gence in the first direction. In some examples, the partially 

collimated laser beam diverges less in the first direction than 

in the second direction. The transmit/receive lens receives the 

partially collimated laser beams from the one or more light 

sources via a transmission path and collimates the partially 

collimated laser beams to provide collimated laser beams that are transmitted into an environment of the LIDAR device. 

The collimated light transmitted from the LIDAR device 

into the environment may reflect from one or more objects in 

the environment to provide object-reflected light. The trans 

mit/receive lens may collect the object-reflected light and 

focus the object-reflected light through a focusing path onto 

the one or more detectors. The transmission path through 

which the transmit/receive lens receives the light from the 

light sources may include a reflective element, such as a plane mirror or prism, that partially obstructs the focusing path. 

10 

15 

20 

25 

30 

35 

40 

45 

50 

55 

60 

65 

4 

However, by providing partially collimated laser beams that 

diverge primarily in one direction, the beam widths of the 

partially collimated laser beams can be made relatively small 

in comparison to the aperture of the transmit/receive lens, as can the dimensions of the reflective element that accommo 

dates the beam widths of the partially collimated laser beams. 

FIGS. 1A, 1B, and 1C illustrate an example LIDAR device 

100. In this example, LIDAR device 100 includes light 

sources 102, 104, and 106 and detectors 108, 110, and 112. 

Each of light sources 102, 104, and 106 emits light in a 

wavelength range that can be detected by detectors 108, 110, 

and 112. The wavelength range could, for example, be in the 

ultraviolet, visible, and/or infrared portions of the electro 

magnetic spectrum. In some examples, the wavelength range 

is a narrow wavelength range, such as provided by lasers. In 

addition, the light emitted by light sources 102,104, and 106 

could be in the form of pulses. 

The light that is emitted by light sources 102,104, and 106 

is collimated by a lens 114. The collimated light is then 

transmitted into an environment of LIDAR device 100 via a 

mirror 116. The light transmitted from LIDAR device 100 

could be reflected by one or more objects in the environment. 

The light reflected from such objects may reach mirror 116 

and be reflected into lens 114. Lens 114 may then focus the 

object-reflected light onto one or more of detectors 108, 110, 

and 112. 

Within LIDAR device 100, light sources 102,104, and 106 

could be located in a different area than detectors 108, 110, 

and 112. As shown in FIG.1B, detectors 108, 110, and 112 are 

arranged vertically in a focal plane 120 of lens 114. As shown 

in FIG. 1C, light sources 102, 104, and 106 are arranged vertically in a separately-located focal plane 122 of lens 114. 

Thus, as a top view of LIDAR device 100, FIG. 1A shows 

light source 102 as the top-most light source in focal plane 

122 and shows detector 108 as the top-most detector in focal 

plane 120. 

To reach lens 114, the light emitted from light sources 102, 

104, and 106 may travel through a transmission path defined 

by one or more reflective elements, such as a plane mirror 

124. In addition, light sources 102, 104, and 106 can be 

arranged to emit light in different directions. As shown in 

FIG. 1C, light sources 102, 104, and 106 emit light toward 

plane mirror 124 in directions indicated by rays 132a, 134a, 

and 136a, respectively. As shown in FIG. 1B, rays 132a, 

134a, and 136a, are reflected by plane mirror 124, as rays 

132b, 134b, and 136b, respectively. Rays 132b, 134b, and 

136b then pass through lens 114 and are reflected by mirror 

116. FIG. 1A shows that ray 132bis reflected by mirror 116 as 

ray 132c. Rays 134b and 136b may be similarly reflected by 

mirror 116 but in different vertical directions. In this regard, 

the vertical arrangement of light sources 102, 104, and 106, 

results in rays 132b, 134b, and 136b being incident upon 

mirror 116 at different vertical angles, so that mirror 116 

reflects the light from light sources 102, 104, and 106 in 

different vertical directions. 

Light from one or more of light sources 102,104, and 106 

transmitted by LIDAR device 100 via mirror 116 can be 

reflected back toward mirror 116 from one of more objects in 

the environment of LIDAR device 100 as object-reflected light. Mirror 116 can then reflect the object-reflected light 

into lens 114. As shown in FIG. 1B, lens 114 can focus the 

object-reflected light onto one or more of detectors 108, 110, 

and 112, via respective focusing paths 138, 140, and 142, 

depending on the angle at which lens 114 receives the object 

reflected light. The angle of the object-reflected light received by lens 114 

may depend on which of light sources 102,104, and 106 was 

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US 9,086,273 B1 

7 

slow axis. When this type of laser diode is used in light 

sources 102, 104, and 106, lens 114 could be an aspherical 

lens with a focal length of about 100 mm. It is to be under 

stood that this specific example is illustrative only. Laser 

diode 202 could have a different configuration, different aper 

ture sizes, different beam divergences, and/or emit different 

wavelengths. 

As shown in FIGS. 2B and 2C, cylindrical lens 204 may be 

positioned in front of aperture 206 with its cylinder axis 214 

generally parallel to slow axis 210 and perpendicular to fast 

axis 208. In this arrangement, cylindrical lens 204 can pre 

collimate laser beam 212 along fast axis 208, resulting in 

partially collimated laser beam 216. In some examples, this 

pre-collimation may reduce the divergence along fast axis 

208 to about one degree or less. Nonetheless, laser beam 216 

is only partially collimated because the divergence along slow 

axis 210 may be largely unchanged by cylindrical lens 204. 

Thus, whereas uncollimated laser beam 212 emitted by laser 

diode has a higher divergence along fast axis 208 than along 

slow axis 210, partially collimated laser beam 216 provided by cylindrical lens 204 may have a higher divergence along 

slow axis 210 than along fast axis 208. Further, the diver 

gences along slow axis 210 in uncollimated laser beam 212 

and in partially collimated laser beam 216 may be substan 

tially equal. 

In one example, cylindrical lens 204 is a microrod lens with 

a diameter of about 600 microns that is placed about 250 

microns in front of aperture 206. The material of the microrod 

lens could be, for example, fused silica or a borosilicate 

crown glass, such as Schott BK7. Cylindrical lens 204 could 

also be used to provide magnification along fast axis 208. For 

example, if the dimensions of aperture 206 are 10 microns by 

200 microns, as previously described, and cylindrical lens 

204 is a microrod lens as described above, then cylindrical lens 204 may magnify the shorter dimension (corresponding 

to fast axis 208) by about 20 times. This magnification effec 

tively stretches out the shorter dimension of aperture 206 to 

about the same as the longer dimension. As a result, when 

light from laser beam 216 is focused, for example, focused 

onto a detector, the focused spot could have a substantially 

square shape instead of the rectangular slit shape of aperture 

206. 

FIG. 3 illustrates a scenario in which light sources 102, 

104, and 106 in LIDAR device 100 are each made up of a 

respective laser diode and cylindrical lens, for example, as 

shown in FIGS. 2A-2C. As shown, light source 102 emits a 

partially collimated laser beam 350 that is reflected by plane 

mirror 124 into lens 114. In this example, partially collimated 

laser beam 350 has less divergence in the horizontal plane (the 

drawing plane of FIG. 3) than in the vertical plane. Thus, the 

laser diode in light source 102 may be oriented with its fast 

axis in the horizontal plane and its slow axis in the vertical 

plane. For purposes of illustration, partially collimated laser 

beam 350 is shown in FIG. 3 with no divergence in horizontal 

plane. It is to be understood, however, that some amount of divergence is possible. 

Lens 114 collimates partially collimated laser beam 350 to 

provide collimated laser beam 352 that is reflected by mirror 

116 into the environment of LIDAR device 100. Light from 

collimated laser beam 352 may be reflected by one or more 

objects in the environment of LIDAR device 100. The object 

reflected light may reach mirror 116 and be reflected into lens 

114. Lens 114, in turn, focuses the object-reflected light 

through focusing path 138 onto detector 108. Although FIG. 

3 shows a partially collimated laser beam from only light 

source 102, it is to be understood that light sources 104 and 

106 could also emit partially collimated laser beams that are 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

55 

60 

65 

8 

collimated by lens 114 to provide collimated laser beams that 

are transmitted from LIDAR device 100 via mirror 116. Thus, 

object-reflected light from the collimated laser beams origi 

nating from one or more of light sources 102, 104, and 106 

may reach mirror 116 and be reflected into lens 114, which 

focuses the object-reflected light onto one or more of detec 

tors 108, 110, and 112, respectively. 

As shown in FIG. 3, the transmission path through which 

partially collimated laser beam 350 reaches lens 114 includes 

a plane mirror 124 that partially obstructs focusing path 138. 

However, the obstruction created by plane mirror 124 can be 

minimized by having the dimensions of plane 124 correspond 

to the dimensions of partially collimated laser beam 350 

incident upon it. As shown, partially collimated laser beam 

350 has a beam width 354 in the horizontal plane. Partially 

collimated laser beam 350 also has a beam width in the 

vertical plane (not shown), which could be substantially 

larger than beam width 354 due to the greater divergence in 

the vertical plane. To minimize obstruction of focusing path 

138, plane mirror 124 could have horizontal and vertical 

dimensions that are just large enough to accommodate the 

horizontal and vertical beam widths of partially collimated 

laser beam 350, as well as the horizontal and vertical beam 

widths of the partially collimated laser beams emitted by light 

sources 104 and 106. As a result, plane mirror 124 could have 

a larger cross-section in the vertical plane than in the hori 

zontal plane. 

To illustrate how the dimensions of plane mirror 124 may 

compare to the dimensions of lens 114 in order to minimize 

the obstruction of focusing path 138, FIG. 4, shows a view 

from mirror 116 of lens 114 and plane mirror 124 behind it. 

For purposes of illustration, lens 114 is shown with a gener ally rectangular aperture having a horizontal dimension 400 

and a vertical dimension 402. Of course, other aperture shapes are possible as well. In this example, plane mirror 124 

has a vertical dimension 404 that is the same or similar to 

vertical dimension 402 of lens 114, but plane mirror 124 has a horizontal dimension 406 that is much smaller than the 

horizontal dimension 400 of lens 114. By having horizontal 

dimension 406 of plane mirror 124 be only a fraction of 

horizontal dimension 400 of horizontal dimension 400 of lens 

114, plane mirror 124 may obstruct only a fraction of the 

aperture of lens 114. 

FIGS. 5A and 5B illustrate an example application of a 

LIDAR device 500, which could have the same or similar 

configuration as LIDAR device 100 shown in FIG. 1. In this 

example application, LIDAR device 500 is used to scan an 

environment that includes a road. Thus, LIDAR device 500 

could be in a vehicle, such as an autonomous vehicle, that is 

traveling on the road. The environment of LIDAR device 500 

in this example includes another vehicle 502 and a road sign 

504. To scan through the environment, LIDAR device 500 

rotates a scanning element, which could be the same or simi 

lar to mirror 116, according to motion reference arrow 506 

with angular velocity w. While rotating, LIDAR device 500 

regularly (e.g., periodically) emits pulsed laser beams, such 

as laser beam 508. Light from the emitted laser beams is 

reflected by objects in the environment, such as vehicle 502 

and sign 504, and are detected by one or more detectors in 

LIDAR device 500. Precisely time-stamping the receipt of the 

reflected signals allows for associating each reflected signal 

(if any is received at all) with the most recently emitted laser 

pulse and measuring the time delay between emission of the 

laser pulse and reception of the reflected light. The time delay 

provides an estimate of the distance to the reflective feature 

based on the speed of light in the intervening atmosphere. 

Combining the distance information for each reflected signal 

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US 9,086,273 B1 

with the orientation of scanning element in LIDAR device 

500 for the respective pulse emission allows for determining 

a position of the reflective feature in three-dimensions. 

FIG. 5B symbolically illustrates a point cloud resulting 

from LIDAR device 500 scanning the environment shown in 

FIG. 5A. For purposes of illustration, the scan is assumed to 

be in an x-y plane that is generally horizontal (e.g., parallel to 

the surface of the road). It is to be understood, however, that 

the scan could include a vertical component (z-dimension) as 

well. In this example, the point cloud includes spatial points 

512 corresponding to reflections from vehicle 502 and spatial points 514 corresponding to reflections from sign 504. Each 

spatial point in the point cloud has a line of sight (“LOS”) 

distance from LIDAR device 500 and an azimuthal angle p in 

the x-y plane. In this way, the scanning by LIDAR 500 can 

provide information regarding the locations of reflective 

objects in its environment. 

FIG. 6 is a flow chart of an example method 600 of oper 

ating a LIDAR device, such as LIDAR device 100. Method 

600 involves emitting an uncollimated laser beam from a laser 

diode, in which the laser beam has a first divergence in a first 

direction and a second divergence in a second direction, with 

the first divergence being greater than the second divergence 

(block 602). The laser diode could be configured as shown in 

FIGS. 2A-2C with a fast axis and a slow axis. Thus, the first 

direction could correspond to the fast axis and the second 

direction could correspond to the slow axis. 

Method 600 further involves pre-collimating the uncolli 

mated laser beam in the first direction to provide a partially collimated laser beam that has a third divergence in the first 

direction and a fourth divergence in the second direction, with 

the third divergence being less than the fourth divergence and 

the fourth divergence being substantially equal to the second 

divergence (block 604). The pre-collimation could be 

achieved by transmitting the laser beam through a cylindrical 

lens, as shown in FIGS. 2B and 2C and described above. 

Thus, the cylindrical lens could reduce the divergence along 

the fast axis so that it becomes less than the divergence along 

the slow axis, while keeping the divergence along the slow 

axis substantially the same. 

A lens, such as lens 114 shown in FIGS. 1A and 1B, 

collimates the partially collimated laser beam to provide a 

collimated laser beam (block 606). The lens could be an 

aspherical lens or a spherical lens. The collimated laser beam 

is then transmitted into an environment (block 608). Trans 

mitting the collimating laser beam into the environment could 

involve a rotating mirror, such as mirror 116, reflecting the 

collimated laser beam from the lens into the environment. 

Method 600 also involves collecting object-reflected light, 

in which the object-reflected light includes light from the 

collimated laser beam that has reflected from one or more 

objects in the environment (block 610). Collecting the object 

reflected light could involve a rotating mirror, such as mirror 

116, reflecting the object-reflected light from the environ 

ment into the lens used to collimate the laser beam. The lens 

may also focus the object-reflected light through a focusing 

path onto a detector (block 612). In some examples, the lens 

may receive the partially collimated laser beam via a reflec 

tive element, such as a plane mirror or prism, that partially 

obstructs the focusing path. However, as discussed above, the 

obstruction can be minimized by having the dimensions of the 

reflective element match the dimensions of the partially col 

limated laser beam. 

Although method 600 has been described with respect to 

one laser diode, it is to be understood that multiple laser 

diodes could be used, each emitting a respective laser beam 

that is transmitted into the environment as a collimated laser 

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beam. The collimated laser beams could be transmitted 

simultaneously or sequentially. Further, the collimated laser 

beam could be transmitted in different direction. The object 

reflected light that is collected could include light from any of 

the transmitted collimated laser beams. 

While various example aspects and example embodiments 

have been disclosed herein, other aspects and embodiments 

will be apparent to those skilled in the art. The various 

example aspects and example embodiments disclosed herein 

are for purposes of illustration and are not intended to be 

limiting, with the true scope and spirit being indicated by the 

following claims. 

What is claimed is: 

1. A light detection and ranging (LIDAR) device, compris 

1ng: 

at least one laser diode, wherein the at least one laser diode 

is configured to emit an uncollimated laser beam com 

prising light in a narrow wavelength range, wherein the 

uncollimated laser beam has a first divergence in a first 

direction and a second divergence in a second direction, 

and wherein the first divergence is greater than the sec 

ond divergence; 

at least one cylindrical lens, wherein the at least one cylin drical lens is configured to pre-collimate the uncolli 

mated laser beam in the first direction to provide a par tially collimated laserbeam that has a third divergence in 

the first direction and a fourth divergence in the second 

direction, wherein the third divergence is less than the 

fourth divergence and the fourth divergence is substan 

tially equal to the second divergence; 

at least one detector, wherein the at least one detector is 

configured to detect light having wavelengths in the 

narrow wavelength range; and 

an objective lens, wherein the objective lens is configured 

to (i) collimate the partially collimated laser beam to 

provide a collimated laser beam for transmission into an 

environment of the LIDAR device and (ii) focus object 

reflected light onto the at least one detector, wherein the 

object-reflected light comprises light from the colli 

mated laser beam that has reflected from one or more 

objects in the environment of the LIDAR device. 

2. The LIDAR device of claim 1, wherein the objective lens 

receives the partially collimated laser beam via a transmission 

path and focuses the object-reflected light through a focusing 

path, and wherein the transmission path includes a reflective 

element that partially obstructs the focusing path. 

3. The LIDAR device of claim 2, wherein the reflective 

element comprises a plane mirror. 

4. The LIDAR device of claim 1, wherein the at least one 

laser diode comprises a plurality of laser diodes, the at least 

one detector comprises a plurality of detectors, and the at least 

one cylindrical lens comprises a plurality of cylindrical 

lenses, such that each cylindrical lens in the plurality of cylin 

drical lenses is associated with a corresponding laser diode in 

the plurality of laser diodes. 

5. The LIDAR device of claim 4, wherein each laser diode 

is configured to emit a respective uncollimated laser beam in 

a respective direction, and wherein each cylindrical lens is 

configured to pre-collimate the uncollimated laser beam pro 

duced by its corresponding laser diode to provide a corre 

sponding partially collimated laser beam that is then colli 

mated by the objective lens to provide a corresponding 

collimated laser beam. 

6. The LIDAR device of claim 5, wherein each detector in 

the plurality of detectors is associated with a corresponding 

laser diode in the plurality of laser diodes, and wherein the 

objective lens is configured to focus onto each detector a 

Case 3:17-cv-00939-WHA Document 1-3 Filed 02/23/17 Page 13 of 14
US 9,086,273 B1 

11 

respective portion of the object-reflected light that comprises 

light from the detector’s corresponding laser diode. 

7. The LIDAR device of claim 6, wherein each laser diode 

has a rectangular aperture that has a short dimension and a 

long dimension, and wherein each cylindrical lens is config 

ured to magnify the short dimension of the aperture of its 

corresponding laser diode such that the light from the laser 

diode that is focused onto the laser diode's corresponding detector has a substantially square shape. 

8. The LIDAR device of claim 1, wherein the at least one 

cylindrical lens comprises at least one microrod lens. 

9. The LIDAR device of claim 1, wherein the narrow wave 

length range includes wavelengths of about 905 nanometers. 

10. The LIDAR device of claim 1, wherein the objective lens is an aspherical lens. 

11. The LIDAR device of claim 1, further comprising a 

mirror, wherein the mirror is configured to reflect the colli 

mated laser beam from the objective lens into the environ 

ment and to reflect the object-reflected light from the envi 

ronment into the objective lens. 

12. The LIDAR device of claim 11, wherein the mirror 

rotates about a vertical axis. 

13. The LIDAR device of claim 12, wherein the mirror 

comprises a plurality of reflective surfaces, each reflective 

surface having a different tilt with respect to the vertical axis. 

14. A light detection and ranging (LIDAR) device, com 

prising: 

a plurality of light sources, wherein each light source is 

configured to emit partially collimated light; 

a plurality of detectors, wherein each detector in the plu rality of detectors is associated with a respective light 

source in the plurality of light sources; 

a first mirror, wherein the first mirror is configured to 

reflect the partially collimated light from the light sources; 

a second mirror, wherein the second mirroris configured to 

rotate about an axis; and 

a lens, wherein the lens is configured to (i) receive, via the 

first mirror, the partially collimated light from the light 

sources, (ii) collimate the partially collimated light from 

the light sources to provide collimated light, wherein the 

second mirror is configured to reflect the collimated 

light from the lens into an environment of the LIDAR 

device, and (iii) focus, via a focusing path, onto each 

detector any object-reflected light from the detector’s 

associated light source that has reflected from one or 

more objects in the environment of the LIDAR device, 

wherein the second mirror is configured to reflect the 

object-reflected light from the environment into the lens, 

wherein the first mirror partially obstructs the focusing path. 

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15. The LIDAR device of claim 14, wherein each light 

source in the plurality of light sources comprises a respective 

laser diode and a respective cylindrical lens. 

16. The LIDAR device of claim 14, wherein the second 

mirror comprises a plurality of reflective surfaces, each 

reflective surface having a different tilt with respect to the 

axis. 

17. A method comprising: 

emitting an uncollimated laser beam from a laser diode, 

wherein the uncollimated laser beam has a first diver 

gence in a first direction and a second divergence in a 

second direction, and wherein the first divergence is 

greater than the second divergence; 

pre-collimating the uncollimated laser beam in the first 

direction to provide a partially collimated laser beam, 

wherein the partially collimated laser beam has a third 

divergence in the first direction and a fourth divergence 

in the second direction, and wherein the third divergence 

is less than the fourth divergence and the fourth diver 

gence is substantially equal to the second divergence; 

collimating, by a lens, the partially collimated laser beam 

to provide a collimated laser beam; 

transmitting the collimated laser beam into an environ 

ment; 

collecting object-reflected light, wherein the object-re 

flected light comprises light from the collimated laser 

beam that has reflected from one or more objects in the 

environment; and 

focusing, by the lens, the object-reflected light through a 

focusing path onto a detector, wherein the lens receives 

the partially collimated laser beam via a plane mirror 

that partially obstructs the focusing path. 

18. The method of claim 17, wherein pre-collimating the 

uncollimated laser beam in the first direction to provide a 

partially collimated laser beam comprises transmitting the 

uncollimated laser beam through a cylindrical lens. 

19. The method of claim 17, wherein transmitting the col 

limated laser beam into an environment comprises a rotating 

mirror reflecting the collimated laser beam from the lens into 

the environment, and wherein collecting object-reflected light comprises the rotating mirror reflecting the object-re 

flected light from the environment into the lens. 

20. The method of claim 17, further comprising: rotating an optical assembly about an axis while transmit 

ting the collimated laser beam into the environment and 

collecting object-reflected light, wherein the optical 

assembly includes the laser diode, the lens, the detector, 

and the plane mirror. 

Case 3:17-cv-00939-WHA Document 1-3 Filed 02/23/17 Page 14 of 14