Updated February 4, 2000
General Science Department
I. Test Purpose
This test is used to determine the power, intensity, & spectral emission of visible light dental resin curing lights.
II. Summary of Test Method
A reasearch radiometer, integrating sphere, & scanning monochromator, calibrated within the last 12 months, are used for all measurements. Power is measured using an integrating sphere. Intensity is calculated by dividing the power by the light tip area (or spot size). Spectral emission is measured from 350 - 1100 nm, with detailed measurements from 350 - 550 nm.
III. Equipment and Materials
1. curing light
2. IL1500 research radiometer (International Light)
3. INS250 integrating sphere with detector (International Light)
4. IL587 scanning monochromator with detector (International Light)
5. calculator
6. digital calipers
7. timer
8. ADC data acquisition system (National Instruments, LabPC+)
9. ring stand with clamps
IV. Test method
A. Power:
1. Using ring stand with clamps, position light tip in user port of sphere, with tip surface tangent to inner surface of sphere.
2. Connect detector of sphere to radiometer.
3. Connect radiometer output to data acquisition system.
4. Warm up light by activating for several curing cycles.
5. Start data acquisition system.
6. Activate light for desired curing cycle.
7. Stop data acquisition.
8. Save data to file.
9. Analyze power data using Microsoft Excel or comparable software. Possible parameters to evaluate include: initial power, final power, average power, change in power in ramp or step modes, etc. Record power as P, in milliwatts.
B. Intensity:
1. Measure the effective diameter of the light tip, in millimeters, using the digital calipers. Record as d.
2. Calculate the effective area of the light tip. Record as A, in square centimeters. A = p (d/20)2.
3. Calculate the approximate intensity by dividing the power by the area of the light guide. Record as I, in milliwatts per square centimeter. I = P/A.
4. The intensity calculation is an approximation since you are assuming that the power is uniformly distributed over the light tip area. If there is an obvious "hot spot" on the surface of the light tip, a better approximation may be to divide the power by the area of the hot spot.
C. Spectral Emission:
1. Connect detector of monochromator to radiometer.
2. Connect radiometer output to data acquisition system.
3. Set sensitivity factor on radiometer to 1.
4. Using ring stand with clamps, position light tip in front of SW-1 diffuser window on monochromator, just touching window & centered over quartz diffuser.
5. Set vernier dial to 300 nm.
6. Activate light.
7. Simultaneously start data acquisition & begin scanning with monochromator.
8. Scan wavelengths from 300 to 1100 nm. Reactivate light as necessary.
9. Stop data acquisition.
10. Save data to file.
11. Analyze spectral data using Microsoft Excel or comparable software.
12. Some lights will not stay on for more than a few seconds, making scans impossible. Instead, collect the spectral measurements every 5 nm between 350 & 550 nm, advancing the monochromator by hand using the vernier dial, & activating the light for each measurement.