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| d2:laser_controller [2020/05/04 19:02] – Michael Radunsky | d2:laser_controller [2020/05/29 21:47] – Michael Radunsky |
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| <WRAP center round tip 80%> | <WRAP center round tip 80%> |
| If the LED indicator does not turn on when the Laser ON-OFF/Reset switch is flipped up, make sure both interlocks are engaged and that the COARSE CURRENT knob is turned up at least half a turn. If the current is set to 0 mA when you engage the Laser ON switch, the system detects an open circuit (no current flowing) and indicates an error. Due to the "soft start" circuitry employed in the current source, you may safely leave the current at its operating setpoint when engaging and disengaging the Laser ON switch. | If the LED indicator does not turn on when the Laser ON-OFF/Reset switch is flipped up, make sure both interlocks are engaged and that the COARSE CURRENT knob is turned up at least half a turn. If the current is set to 0 mA when you engage the Laser ON switch, the system detects an open circuit (no current flowing) and indicates an error. Due to the "soft start" circuitry employed in the current source, you may safely leave the current at its operating setpoint when engaging and disengaging the Laser ON switch. The soft start limits the ramp time of the current to the set point to >300 ms. |
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| If the LED indicator turns on for ~5 seconds and then turns off, check your laser diode connection to see if it is open (or if the diode is backwards). | If the LED indicator turns on for ~5 seconds and then turns off, check your laser diode connection to see if it is open (or if the diode is backwards). |
| ====User Control of the Poles and Gain==== | ====User Control of the Poles and Gain==== |
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| If you remove the right side panel on the Laser Controller, for each stage of temperature control, you will see the panel shown in <imgref side_adjustb>. The set of click switches labeled "Integral" controls the PI (ω<sub>1</sub>) pole. <color black/yellow>Clicking the first switch, labeled "proportional," into the on position removes the integral gain (but not the differential gain).</color> If the "proportional" switch is in the off position (integral gain is now on), then the sum of the times for all switches in the on position gives the RC time-constant for the PI pole. For example, if the 2<sup>nd</sup> (0.47s) switch and the 4<sup>th</sup> (2.2s) switch are in the on position (and the rest off), then the time constant is 2.7s and ω<sub>1</sub> = 1/2.7s = 0.37 Hz. | If you remove the right side panel on the Laser Controller, for each stage of temperature control, you will see the panel shown in <imgref side_adjustb>. The set of click switches labeled "Integral" controls the PI (ω<sub>1</sub>) pole. <color black/yellow>Clicking the first switch, labeled "proportional," into the on position removes the integral gain (but not the differential gain). If the "proportional" switch is in the off position (integral gain is now on), then the sum of the times for all switches in the on position gives the RC time-constant for the PI pole.</color> For example, if the 2<sup>nd</sup> (0.47s) switch and the 4<sup>th</sup> (2.2s) switch are in the on position (and the rest off), then the time constant is 2.7s and ω<sub>1</sub> = 1/2.7s = 0.37 Hz. |
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| Similarly, the switches labeled "Differential" control the D (ω<sub>2</sub>) pole. If the first switch, labeled "Diff On" is in the off position, then there is no differential pole. If the "Diff On" switch is on, then the D pole has an RC time-constant given by the sum of the times of all the switches in the on position, same as with the Integral bank of switches. | Similarly, the switches labeled "Differential" control the D (ω<sub>2</sub>) pole. If the first switch, labeled "Diff On" is in the off position, then there is no differential pole. If the "Diff On" switch is on, then the D pole has an RC time-constant given by the sum of the times of all the switches in the on position, same as with the Integral bank of switches. |
