THORLABS LD2000R, Руководство пользователя

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OEM Laser Diode Driver Chapter 4: LD2000R Overview
Page 6 0187-D01
4.4. Theory of Operation
The LD2000R uses the internal monitor photodiode provided on most low power
diode lasers for feedback when operating in the Constant Power Mode. The
following figure is a block diagram of the LD2000R laser driver.
Figure 2 LD2000R Simplified Block Diagram
The laser power is regulated through an integrating feedback loop. The setpoint of
the feedback is determined by the PWR LIMIT control trimpot and the OUTPUT
ADJUST knob (in external modulation mode, the external voltage is used in place
of the OUTPUT ADJUST). An internal transimpedance amplifier converts the laser
feedback current to a voltage that is used as the error signal for the feedback loop.
Since all analog signal levels are based on a 2.5 V internal reference, we will use
this to derive the feedback gain setting resistor value: