Examples of stereoscopic viewing equipment:

 

red & green (blue) glasses
-the other eye sees the red image, the other sees the green

polarised glasses
-the images are filtered through lenses polarised in different directions

mirror apparatus'
-the images are directed to the same apparent spot by mirrors

Viewmaster-type equipment
-small slides are magnified and sharpened by appropriate lenses to be viewed from a short distance

LCD shutter glasses
-the glasses cover each eye in turn very rapidly; the images are swapped on the monitor in the same frequency

data helmets or glasses
-the images are located into small computer monitors placed very near to the eyes; lenses are used to focus the images