Advanced Laser Engine Features

Setting K-Clock Delay

The k-clock delay can be adjusted depending on the length of the fiber used between the engine and the balanced receiver. The k-clock delay can be adjusted between 28.285 ns and 65.58 ns in 0.575 ns intervals (Refer to the OCT Host k-clock delay section for detailed instructions on how to set the clock delay).

Selection of the appropriate delay is dependent on the length of fiber used between the balanced receiver and the Engine. An example detailed drawing of the system configuration is shown below.

The orange plus red path should be matched to the green path plus the electronic delay to achieve transform limited signal reconstruction. To best make use of the full electronic delay, it is best to match the red plus orange paths to the green path plus the mid electronic delay.

28 ns correspond to 8394 mm in air or 5721 mm in fiber. 54 ns correspond to 19186 mm in air or 13078 mm in fiber. Mid range is 9400 mm in fiber.

Example:

(Orange path + Red Path) - Green Path = 13083 mm - 2610 mm = 10473 mm in fiber.

10473 mm in fiber * 1.47 fiber refractive index = 15395 mm in air.

Dividing by speed of light in air: 15.395 m / (299 792 458 m / s) = 51.3 ns

The delay between the clock and the signal is 51.3 ns

Calculating the optical clock delay value that to be set: (51.3 – 28.3) / 0.575 = 40

Operating the Laser Interlock

A hardware interlock exists on every unit to stop the laser emission when Pin 2 of the interlock is disconnected from 3.3 V. (Details on the Interlock electrical pin out can be found here.) The driver board is designed to NOT automatically re-enable laser emission if the interlock pin 2 is reconnected back to 3.3 V. To re-enable laser emission, the interlock pin 2 needs to be maintained at 3.3 V and the laser emission ON command can be done via software (startscan() in API or Run in OCTHost application) or via toggling the digital input to on the Interlock Pin 1.

Switching Configurations

Multiple configurations can be offered with some laser engines. Configurations can vary between dummy clocks ON/OFF and various speeds. These configurations need to be set at the factory or can be done remotely via Tech Support. Refer to switching configurations section for more details.

Operating a Variable Delay Line (VDL)

Refer to these instructions if your Engine includes optional VDL control capabilities.