For safety reason I would like to replace laser LED with standard LED with low radiation angle. What LED would you recommend?

See "Easy Arduino Cat laser Toy Project | NO Soldering DIY"

 

No LED will give you a beam like you'd get from a laser diode without using lenses.

If "standard LED" means through hole, use a 3mm ultra-bright with a non-diffused lens with lenses to focus the light.

 

For safety reason I would like to replace laser LED with standard LED with low radiation angle. What LED would you recommend?

See "Easy Arduino Cat laser Toy Project | NO Soldering DIY"

The cat seems way more distracted by the buzz of the servo motor than entertained by the laser.

 

You might be able to find one like the LED described in the attached file.
It is green 30,000 to 60,000 millicandelas with a 15° beam. The are listed for 10¢each (US) but the minimum order is five. If found this one at my favorite distributor in Bangkok. There should be something similar at other distributors.

Other colors are available in this package -green just happens to have the highest rated light output because us humans are most sensitive around 550 nm. Not sure about cats.

I have never heard of anybody or any cat being injured by one those low powered red laser pointers.

 

You can get 5mm LEDs down to beam angles as low as 4 degrees. Vishay VLCS5830 is an example, rated at up to 65,000mcd at 50mA. Bear in mind that LED beam angles are the angle where intensity drops to 50% of on-axis intensity, so there is beam spill outside of that angle. You will probably still need a lens or deep reflector to tighten up the beam a bit more if you want a small dot at any reasonable distance.

 

You can get 5mm LEDs down to beam angles as low as 4 degrees. Vishay VLCS5830 is an example, rated at up to 65,000mcd at 50mA. Bear in mind that LED beam angles are the angle where intensity drops to 50% of on-axis intensity, so there is beam spill outside of that angle. You will probably still need a lens or deep reflector to tighten up the beam a bit more if you want a small dot at any reasonable distance.

It looks great with 4° only. Any advice where to buy focusing lens for it?

 

It looks great with 4° only. Any advice where to buy focusing lens for it?

You can get the LED from TME in Poland, they also have a couple of small reflectors designed to fit 5mm LEDs, they may also have suitable lenses. You would have to go through their catalogue.

 

Mouser lists LEDs with half angles down to 2.5°

Below 4, they are expensive.

 

FLV-104 was suggested for a "laser simulator" project back in the '80s. It did produce that characteristic twinkling laser illumination effect when shone on a rough surface.
This page says 4 degrees:
http://www.ledmuseum.net/1980.htm