This guide aims to list every laser sight that players can find in every official campaign. Please, feel free to help me out if you have a screenshot of the laser guide spot that I don’t.
 
 
The followings are three guaranteed location for laser sights, while the rest within this guide are only potential:
 
Dead Center, chapter 2 (c1m2): Inside Whitaker’s Gun Shop.
 
Cold Stream, chapter 2 (c14m2): Before the explosive barrels that causes panic event.
 
Cold Stream, chapter 3 (c14m3): Under the bridge, next to the M60 gun.
 
 

Spot Counts in L4D2 Maps

—Dead Center—
 

c1m1_hotel	zero
c1m2_streets	3 potential + 1 guaranteed
c1m3_mall	zero
c1m4_atrium	zero

Total: 4 (four)
 
 
—Dark Carnival—
 

c2m1_highway	7
c2m2_fairgrounds	33
c2m3_coaster	47
c2m4_barns	zero
c2m5_concert	zero

Total: 87 (eighty-seven)
 
 
—Swamp Fever—

c3m1_plankcountry	10
c3m2_swamp	8
c3m3_shantytown	8
c3m4_plantation	zero

Total: 26 (twenty-six)
 
 
—Hard Rain—
 

c4m1_milltown_a       c4m4_milltown_b       c4m5_milltown_escape	11
c4m2_sugarmill_a       c4m3_sugarmill_b	2

Total: 13 (thirteen)
 
 
—The Parish—
 

c5m1_waterfront	zero
c5m2_park	zero
c5m3_cemetry	6
c5m4_quarter	17
c5m5_bridge	zero

Total: 23 (twenty-three)
 
 
—The Passing—
 

c6m1_riverbank	11
c6m2_bedlam	14
c6m3_port	14

Total: 39 (thirty-nine)
 
 
 

Potential spots, L4D2 maps

Dark Carnival, chapter 1 (c2m1):
 
(a) Next to the extinguished campfire.
 
(b) On the motel after hunting rifle. (Credit to jakethenoob – [gamespot.com] )
 
 

 
Dark Carnival, chapter 2 (c2m2):
 
(a) Next to the target bottles and cute, cuddly crocodile plushies; near the start safe room.
 
 

 
Dark Carnival, chapter 2 (c2m2):
 
(b) Next to the slightly-menacing-yet-cuddly snake plush in front of the REFRESHMENTS stand.
 
 

 
 
Hard Rain, chapter 1 and 4 (c4m1 & c4m4):
 
In a house. (Credit to
 

 
)
 
 

 
 
The Parish, chapter 3 (c5m3):
 
(a) In a corner just before dropping through the wall hole.
 
 

 
 
The Parish, chapter 3 (c5m3):
 
(b) On top of the van.
 
 
 

Potential spots, L4D1 maps

 
 
The Sacrifice, chapter 2 (c7m2)
 
Inside the small one-room building in conjunction to the lake.
 
 

 
 
No Mercy, chapter 2 (c8m2):
 
(a) In a corner between two trainwrecks, next to the collapsed wall.
 
 

 
No Mercy, chapter 2 (c8m2):
 
(b) “After generator event, go upstairs, hit the ammo, then go to hallway. Second door on the right, check the shelf,” credit to stewprime – [gamespot.com] 
 
 

 
 
No Mercy, chapter 3 (c8m3):
 
Inside the restroom between two sinks.
 
 
Crash Course, chapter 1 (c9m1):
 
(a) Downstairs near the start point.
 
(b) In the open room after which Zoey confesses that she loooves steam/Steam.
 
 

 
Crash Course, chapter 2 (c9m2):
 
Inside the building across the safe room.
 
 
Death Toll, chapter 3 (c10m3):
 
In a small open shelter, to the left after exiting the safe room.
 
 

 
 
Dead Air, chapter 2 (c11m2):
 
In one of the corners in the office.
 
 
Blood Harvest, chapter 2 (c12m2):
 
Next to the first batch of tier-two guns.
 
 
The Last Stand, chapter 2 (c14m2):
 
In the truck, after dropping down from the tower.
 
 

 
 
I hope you enjoy the Guide we share about Left 4 Dead 2 – Detailed Guide for All Laser Sight Locations in Game – Map Guide; if you think we forget to add or we should add more information, please let us know via commenting below! See you soon!