Bias current control of laser diode instrument to reduce power consumption of the instrument

1. A method of operating a laser diode driver comprising:

producing a bias current comprising a pulse width modulated (PWM) signal having a duty cycle that is less than 100%, the PWM signal having a current level that is less than a threshold current for turning on a laser diode;

applying the bias current to the laser diode, whereby the laser diode remains dark when being driven by the bias current;

producing a main drive current; and

applying the main drive current to the laser diode, wherein the sum of the current level of the bias current and a current level of the main drive current exceeds the threshold current for turning on the laser diode, wherein producing the main drive current includes receiving a trigger signal, and in response to receiving the trigger signal, producing a current pulse, and wherein the current pulse is narrower than a first pulse of the bias current and has a falling edge that coincides with a falling edge of the first pulse of the bias current.

2. The method of claim 1 , wherein the main drive current is the current pulse.

3. The method of claim 1 , wherein the main drive current is the current pulse and is synchronized with respect to the bias current.

4. The method of claim 1 , wherein the main drive current is the current pulse, and wherein the current pulse has a rising edge that is delayed by the time period T DELAY relative to a rising edge of the first pulse of the bias current.

5. The method of claim 4 , wherein the time period T DELAY is less than twenty milliseconds.

6. The method of claim 1 , wherein producing the bias current includes receiving a second trigger signal, and wherein the bias current is based on the second trigger signal.

7. A method of operating a laser diode driver circuit comprising:

producing a first current pulse having a duration of time t1;

driving an output terminal of the laser diode driver circuit with the first current pulse, whereby a laser diode that is connected to the output terminal is driven by the first current pulse, an amplitude of the first current pulse being insufficient to turn on the laser diode;

producing a second current pulse;

driving the output terminal with the second current pulse during the period of time t1 in addition to driving the output terminal with the first current pulse, wherein an amplitude of the second current pulse plus the amplitude of the first current pulse being sufficient to turn on the laser diode; and

receiving a trigger signal, wherein producing the first current pulse is performed responsive to receiving the trigger signal.

8. The method of claim 7 , wherein the first current pulse has a first rising edge, wherein the second current pulse has a second rising edge, and wherein the second rising edge occurs a time period T DELAY after the first rising edge.

9. A method of operating a laser diode driver circuit comprising:

producing a first current pulse having a duration of time t1;

driving an output terminal of the laser diode driver circuit with the first current pulse, whereby a laser diode that is connected to the output terminal is driven by the first current pulse, an amplitude of the first current pulse being insufficient to turn on the laser diode;

producing a second current pulse;

driving the output terminal with the second current pulse during the period of time t1 in addition to driving the output terminal with the first current pulse, wherein an amplitude of the second current pulse plus the amplitude of the first current pulse being sufficient to turn on the laser diode; and

receiving a trigger signal, wherein producing the second current pulse is performed responsive to receiving the trigger signal.

10. The method of claim 9 , wherein a pulsewidth of the second current pulse is less than a pulsewidth of the first current pulse.

11. The method of claim 9 , wherein the first current pulse is part of a pulse width modulated signal having a duty cycle less than 100%.

12. The method of claim 9 , wherein the laser diode turns on in response to a rising edge of the second current pulse.

13. The method of claim 9 , wherein the first current pulse has a first rising edge, wherein the second current pulse has a second rising edge, and wherein the second rising edge occurs a time period T DELAY after the first rising edge.

14. The method of claim 13 , wherein the time period T DELAY is less than twenty milliseconds.

15. A method of operating a laser diode driver circuit comprising:

producing a first current pulse having a duration of time t1;

driving an output terminal of the laser diode driver circuit with the first current pulse, whereby a laser diode that is connected to the output terminal is driven by the first current pulse, an amplitude of the first current pulse being insufficient to turn on the laser diode;

producing a second current pulse;

driving the output terminal with the second current pulse during the period of time t1 in addition to driving the output terminal with the first current pulse, wherein an amplitude of the second current pulse plus the amplitude of the first current pulse being sufficient to turn on the laser diode;

receiving a first trigger signal, wherein producing the first current pulse is performed responsive to receiving the first trigger signal; and

receiving a second trigger signal, wherein producing the second current pulse is performed responsive to receiving the second trigger signal.