Need a quick screen to shield sleeping baby from light.

2tall backed chairs. Drape blanket over chairs. The chairsp don't have to be right beside each othe

Put some decorative non-adhesive window film on the window to diffuse the light. https://www.amazon.com/s/ref=nb_sb_ss_i_1_18?url=search-alias%3Daps&field-keywords=decorative+non-adhesive+window+film&sprefix=decorative+non-adh%2Caps%2C237&crid=220PSXZCZ8C3U

There are screens that attach to windows with suction cups that can be used in-home or for traveling. Visit the baby sections in the stores that you shop at or stop at a local DIY for suggestions.

where or what is the light source and where is the baby sleeping?

If you're needing to block light from a window use curtains or shades. If for use in a car you can get window shades are at auto stores. For a play pen secure a blanket with giant clothes pins or spring wood clamps.

Is it a window? They make light block curtains, I use them in my sons room!! I got mine at Target!

Get a large cardboard box from appliance store. Cut and fold into zig-zag so it will stand up like a privacy screen. You can cover with fabric or contact paper. Easy to toss out when baby outgrows need for it. Good luck and hug baby for me!