Adding the envelope - the extra dimension of glass and light

I find it very interesting to try and photograph glass as if it had a fourth dimension; so that we see it in its 'material' 3-dimensional sense,  and at the same time, its caustic counterpart or envelope of light added in to the image.  Here are a few examples I have captured recently:

'Reaching in' 

'Spaces within spaces'

'Spin off'