One of the most common questions we answer at OFH is: 'What size lens do I need to create the needed beam angle?' Using the calculator below will give you a rough estimate. Enter the size of your LED chip ( or select from one of the defaults we have entered) and the desired lens size to calculate the achievable beam angle. Note that estimate works for LEDs with Lambertian beam angular profile. Most of LEDs produce Lambertian beam.

Calculate beam angle of TIR lens

Lens diameter, mm:


LED source size, mm:

LED has round source shape

FWHM is full width of beam angle profile measured at half maximum of luminous intensity center peak. A typical profile for TIR (total internal reflection) lens is shown above. The example shows a beam half angle of around 7-8 degrees

Calculate beam angle of reflector

Reflector diameter, mm:


Reflector height, mm:


LED source size, mm:

LED has round source shape

 
How to measure size of round shaped LED source

How to measure size of round shaped LED source

Reflectors produce uncontrolled or 'spill' light around main spot. A typical profile for reflector is shown above, compared to the TIR image you will notice more light power at angles above the target angle.

 

 

How to measure size of LED with square chip

How to measure size of LED with square chip