To determine if the LED lamp was compatible with the fluorescent, the light output was measured at fixed intervals. Both the fluorescent lamp and the LED lamp were attached at a fixed height. Then two degree increments were marked on the floor using the simple tan law. Light was measured with an illuminance meter. Four tests were performed using this method. The first was a measurement of the fluorescent lamp. The second was a measurement of the LED lamp undiffused. Following this test it was determined that the light should be diffused to ensure that the room was evenly lit. The third test was the diffused LED lamp. Then a test was performed with the diffuser over the fluorescent lamp to determine the efficiency of it.
[Source] LED Ideas