I made some rough measurements, using the setup I had used for CCD calibration, to get an idea of how good of a Lambertian scatterer the white paper is. Following are the values I got:
| Angle (degrees) |
Photodiode reading (V) |
Ps (W) |
BRDF (per str) |
% error |
| 12 |
0.864 |
2.54E-06 |
0.334 |
20.5 |
| 24 |
0.926 |
2.72E-06 |
0.439 |
19.0 |
| 30 |
1.581 |
4.65E-06 |
0.528 |
19.0 |
| 41 |
0.94 |
2.76E-06 |
0.473 |
19.8 |
| 49 |
0.545 |
1.60E-06 |
0.423 |
22.5 |
| 63 |
0.371 |
1.09E-06 |
0.475 |
28 |
Note: All the measurements are just rough ones and are prone to larger errors than estimated.
I also measured the transmittance of the white paper sample being used (it consists of 2 white papers wrapped together). It was around 0.002 |