Originally Posted by Zarf4

For video I've recorded the output of near-IR laser diodes using an old CCD-pickup video camera (mini-DV tape). Like others have said you need something to reflect/refract some of the photons in the air to your pickup. Dust or chalk will work but can be messy -- In a darkened room I used a ultrasonic cold mist humidifier to cover a larger area with a fine mist spray bottle of water to highlight different areas along the beam to show the divergence.