Overview of RM9-PD Radiometer:

User 's Manual

The RM9-PD radiometer is a calibrated sensor for measuring the power of femtowatt CW or quasi CW lasers and light sources. The RM9-PD uses a photodiode sensor in conjunction with an 18Hz chopper (not included, use RMC1 or other chopper). The sensor's power range is from 300fW (femtowatt) to 300nW (nanowatt). It has an 8mm aperture and covers the spectral range from 0.2μm to 1.1μm.

RM9-PD Product drawings

Main parameter：

Problem summary：

How to Use RM9 Radiometer to Improve Measurement Accuracy？

RM9 is only sensitive to signals chopped at 18 Hz, so placing the chopper as close to the laser source as possible can greatly reduce stray light entering the chopper and being read as part of the signal. The noise specification is based on a 10 second moving average. Set the power meter to the average of the measured values for better performance.

Why does the chopper have a defined direction？

A typical chopper has the same type of surface on both sides: metal, low radiation or black, high radiation. When the laser beam is blocked, the metal surface will reflect or scatter most of the laser power, which may cause stray reflection to reach the sensor. The black surface solves this problem, but if the chopper is close to the RM9 or RM9-THz sensor, they will receive the thermal signal from the chopper blade. The stray reflection and thermal signal from the blade will affect the measurement accuracy, so it is necessary to define the direction.