6A60.10-Blackboard optics – lenses

6a6010blackboard optics lenses-1 6a6010-2
Description: This demonstration shows how a concave and convex lens works.


  • Blackboard optics laser
  • Laser power adapter
  • Convex lens
  • Concave lens
  • Blackboard clamp
  • Clay

Setup Procedure:

  1. Place the laser on the blackboard and plug in the power adapter.
  2. Remember to collect the laser off the blackboard (common mistake!)

Demonstration Procedure:

  1. Attach the convex lens to the blackboard clamp and place it on the blackboard.
  2. Turn on the laser (press down and over).
  3. Note that the laser light converges when it leaves the lens at the focal point (see first picture).
  4. Take off the convex lens and attach the concave lens to the blackboard clamp.
  5. Note that the laser light diverges when it leaves the lens (see second picture).
  6. When finished, turn off the laser.
  7. If you wish to block any of the laser’s during this demonstration, use the provided clay as shown in the pictures.

Laser Light Laser Light
Do not stare at the laser beam. Do not point the laser at students.

Note: To help students see the laser light, put some chalk on the chalk board.