This calculator will calculate typical beam intensity min/max ranges for an **ILT Light Measurement System** you may be interested in purchasing based on your intended measurement distance to help determine if it will meet your measurement specifications/requirements. This calculator may also be used to calculate the min/max measurement ranges in beam intensity as well as new sensitivity factors to measure directly in beam intensity based on your existing systems sensitivity factor in foot-candles/lux.

**Beam Candela**

Beam Candela, not to be confused with Mean Spherical Candela (which must be measured in an integrating sphere) is the measure of the lumens per steradian at the peak intensity of the beam and samples only a very narrow angle of the beam. The sampling angle need not be defined.

**PLEASE NOTE:** This calculator uses a simplified version of the Blondel-Rey-Douglas equation to calculate the min/max ranges for flashing light sources. This calculator assumes that the pulse duration is 10ms or faster. Pulses slower than 10 ms start to introduce significant error into the calculation.

**Instructions to calculate TYPICAL Beam Intensity Measurement Ranges**

STEP 1:Enter the intendedMEASUREMENT DISTANCEin this box. This number can be entered in decimal format (i.e. "0.000341") or in scientific notation (i.e. "3.41e-04"). Select whether the distance you are working with is in meters or in feet. If you are measuring in units less than meters or feet (i.e. millimeters or inches) you will have to convert these numbers up to meters or feet first.

STEP 2:Select whichILT Radiometer/Light Meteryou are using or intend to purchase.Please Note:The ILT1400A cannot be used with flashing light sources.

STEP 3:Select whichinput opticyour detector is equipped with or the input optic of the system you are interested in purchasing. The L30 is our high-gain lens and is generally used for intensity measurements at distances greater than 25 feet (7.62 meters). Our H hood is generally used for intensity measurements at distances under 25 feet (7.62 meters). If your existing detector does not have one of these input optics, this calculator cannot be used and you will need to contact our technical support department for assistance.

OUTPUT:These are the typicalMINIMUM & MAXIMUM MEASUREMENT RANGESin beam candela (cd) at the specified distance. The ranges are given for both steady sources and for flashing sources (ILT1700 only).

**Instructions to calculate CUSTOM Beam Intensity Measurement Ranges and Sensitivity Factors**

STEP 1:This is theORIGINALsensitivity factor from your detectors calibration certificate. This number is normally shown on the certificate in scientific notation (i.e. "3.41e-04") and includes optical units such as "(amps)(m2)(lm-1)". For the purpose of this calculator, you only need to enter the number in scientific notation here not the optical units.

STEP 2:Select whichILT Radiometer/Light Meteryou are using.Please Note:The ILT1400 cannot be used with flashing light sources.

STEP 3:Enter the intendedMEASUREMENT DISTANCEin this box. This number can be entered in decimal format (i.e. "0.000341") or in scientific notation (i.e. "3.41e-04"). Select whether the distance you are working with is in meters or in feet. If you are measuring in units less than meters or feet (i.e. millimeters or inches) you will have to convert these numbers up to meters or feet first.

OUTPUT:These are your detectorsMINIMUM & MAXIMUM MEASUREMENT RANGESin beam candela (cd) at the specified distance. The ranges are given for both steady sources and for flashing sources (ILT1700 only). Also displayed areNEWcalculated sensitivity factorsthat may be used in place of the existing sensitivity factor given in Step 1 to measure directly in Candela for steady sources or Effective Candela for flashing sources (ILT1700 only) at the specified measurement distance.