Tools

Optical Power Measurements.

Procedure

  1. Turn on the optical power meter and the HeNe Laser. Wait for about 15 minutes in order for the HeNe laser output to stabilize.
  2. Align the Laser and the power meter for maximum meter reading. This gives the value of Pi in dBm, record it in table 1. [Take extra care not to move the laser source or the power meter after you take this reading].
  3. Insert the glass slide (the glass slide marked with 8 circles) between the laser source and the power meter. The slide should be positioned so that the laser beam passes through circle number 1. [The glass slide must be kept clean, by holding the slide on the sides only].
  4. Record the power meter reading in table 1 in the column marked Po.
  5. Repeat step 5, when the light passes through circles number 2 through 8.
  6. Calculate and record the power loss in dB (dBLoss=Pi-Po) for each of the 8 cases.
  7. Calculate the average experimental dB loss and record its value in table.
  8. Plot the dBLoss versus circle number.
  9. Compare the experimental results obtained in table 1 with the theoretical range of the dB power loss. Are the results within the predicted range?
  10. Compare the average theoretical and average experimental dB power losses.
  11. Discuss the results, write comments and some conclusions.

Figure 1: Set up for Optical Power Measurements