The lasers themselves take 3 LR44 batteries (Small 1.5 V batteries) to function.
The 3 batteries will be in series, giving a total of 3*1.5 = 4.5V. This is below the voltage supplied by the Arduino's 5V pin, so that could feasibly be used to supply the power.
However, first you will need to know the current draw of the lasers. I would recommend removing the batteries and connecting them somehow with wires so you can connect an ammeter in series with them to measure the current draw when the laser is on. Only then will you be able to determine if the Arduino is capable of providing the power.
If the total current draw for ALL the lasers together is greater than a hundred milliamps or so then I would forget it - the voltage regulator on the Arduino, while rated at 800mA, would struggle to dissipate the heat and will get hot.
In this case an external power supply will be required (either the existing batteries, or a wall wart that can provide 4.5V).
If the current is low enough, you can use Ohm's law to calculate the resistance per laser to use to drop the 0.5v from the 5v supply to 4.5v.