this is a brilliant sequrity device,a lazer sequrity alarm is used to catch hold of some nasty thieves who clme in your house and steal your goods. In my lazer sequrity alarm i just made a non - sensitive light detector and a lazer pointed towards the ldr whenever anyone crosses the lazer line the path of lazer towards is blocked and the circuit activates a buzzer.

Step 1: Materials and Tools Required-

(VERY SORRY FOR THE LACK OF PHOTOS)
electrical requirements-
transistor 2n2222
resistors- 56 ohms×2
1 k ohm ×1
ldr (light dependant resistor)
battery cap ×2
9v battery ×2
lazer diode
buzzer or a relay switch

tools required-
soldering iron
soldering wire
nipper
wet sponge
multimeter
etc

extra -
solder fume extractor
and at last your brain!

Step 2: Circuit Diagram-

Step 3: Lets Begin !!!

add a battery cap to your lazer diode in the correct polarity
and connect it to a 9v high ampere battery.

Step 4: Lets Make the Circuit !

(VERY VERY SORRY FOR THE LACK OF PHOTOS )

now at first take your 2n2222 transistor and inser it in your pcb, then solder a 56 ohm resistor and a 1 k ohm resistor in series with the collector of the transisitor now one end of the transistor was soldered to the collector now solder the left out wire to the base of the transisitor
then solder one leg of the ldr to the point where the resisitor and base of the transisitor is soldered and then soder the left out leg of the ldr to the negative terminal of the battery cap, and solder the possitive terminal to the point where the resistor series and collector of the transisitor are soldered,now solder the possitive terminal of the buzzer to the emitter of the transistor and the negative one to the point where the negative terminal of the battery cap and ldr are soldered.

Step 5: Enjoy!!!

now align the lazer pointer to the ldr and connect batteries to the circuits and sequre your surroundings.
(AGAIN VERY SORRY FOR THE LACK OF DETAILED PHOTOS)
now you may connect a relay swith in place of the buzzer and operate something else
one circuit , Infinite possibilities.

thanks for viewing !