How can I insert glass into an interior hollow core door?

Hi Jean, you can. Here's some ideas

https://www.instructables.com/id/Fit-glass-panel-to-hollow-core-door/

This isn't exactly what you want, but I was able to replace a hollow core door with an interior french door for a reasonable price (and it was easier than cutting the existing door). Good luck!

Thank you. I will look at the cost of replacement doors. Annie: the instructions to replace with glass was exactly what I was looking for. I need to find out the cost of tempered glass though. There are children in the house. Thanks

Would probably look much nicer if you replaced with a door with glass in it already. If you are dealing with a dark hallway why not go with the fake window idea?

Solution: place a large mirror on a wall. Glue molding vertically and horizontally on mirror to make it look like a window. Install decorative curtain rod above and hang a pair of stylish drapes to finish the look. Basement lighting will bounce off the mirror (window) and reflect back into the room giving the illusion of a real window.

Hi, Jean!

I live in a mobile home and actually cut holes in my exterior doors to add glass panels. The tutorial can be found here, and should work with hollow interior doors, as well. Hope this helps...

These are really good suggestions. Lots of things I had never thought of. Great bunch of people. Thank you.

You could try your local Habitat for Humaity ReStore shop or another salvage type store, see if they have doors already with glass in them. Tempered glass can be quite expensive.