External Triggering of Spectral Confocal Sensors

2021-09-15

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How do spectral confocal sensors achieve external triggering and scanning? One application of spectral confocal sensors is to measure the thickness of multiple layers of transparent materials. Unlike other measurement methods, when measuring such objects, spectral confocal sensors only need to probe once to complete the measurement. The sensors measure the reflected light on the front and back sides of the measured object to obtain layer thickness information.

Synchronization of spectral confocal sensors and external scanning devices is an important issue in some applications. The CCS-100 can serve in both a "master" and "slave".

Spectral confocal sensor synchronous sensor and other devices

Often, it is necessary to synchronize sensors with external devices, such as encoders, motion controllers, or photocells, which can indicate the path of moving objects on a conveyor belt.

This task is very simple when the external device to which the spectral confocal sensor is synchronized is a digital code, as it is automatically synchronized by the CCS-100.

Synchronization of other types of devices (analog encoders, motion controllers) can be achieved using synchronization signals and triggers. The CCS-100 can synchronize with other devices as a "master" (with a "sync out" TTL signal), as a "slave" (with a "sync in" TTL signal), or in mixed mode (both types are used).

The trigger mode specifies how the sensor responds to the rising or falling edge of the Syncin signal. Common to all trigger modes is that the sensor stops measuring as it waits for a "valid" edge on the "sync" interface. Trigger modes can be enabled and disabled in the "Trigger" interface of the CCSmanager software, or can be controlled via DLL or low-level instructions. By default, all trigger modes are turned off, and data is transferred without interruption as soon as the sensor is activated. When the trigger mode is not enabled, the rising and falling edges of the "Syncin" signal are ignored.

Start Trigger Mode for Spectral Confocal Sensors

A simpler trigger mode is "Startonedge". It is initiated by sending the "$TRG" command, which can be initiated from the command terminal or the CCSManager program trigger page.

After receiving the command, the spectral confocal sensor waits for a trigger signal. The measurement starts when a starting (rising or falling) edge is detected at the syncin input. The repetition reliability (jitter) is less than 1 μs.

A typical application for this trigger mode is to start a continuous line scan in a 2D scan of a sample: stable repetition ensures that there is no jitter on the initial continuous scan line.