Philips DVDR3320V/01 Service Manual page 175

Appendix. How to measure optical power
Optical power measurement is measuring actual optical power coming out from an object lens with LD turned on.
thus, In order to measure optical power, LD should to be turned on and environment need to be dark enough.
If necessary, Cover the top side of the sensor with black paper or hand when measuring.
Generally, fluorecent light is about 50 µW, sun light is about 100 mW. so, If this is ignored, optical power setting may not be
set correctly.
Optical power mesurement procedure
1. Adjust optical power meter's λ(wave length) to DVD. (Generally 660 nm)
2. Turn DVD LD on.
3. Place sensor less than 3mm apart from pick-up object lens, perpendicular to lens.
Adjust position so that the center of object lens match to
4. Read monitor's value. (Read Maximum value as moving position slightly)
(Check working unit. Unit should be mW. When LD is dead, µW or nW unit may not be read correctly.)
5. Multiply monitor's value by 100, round off to the nearest integer, then write constant part.
6. Adjust optical power meter's λ (wave length) to CD. (Generally 780 nm)
7. Turn CD LD on.
8. Repeat step 3~5 above.
L mark on the sensor.
5-50
L Display Part