Laser Mode Selection And Signal Selection

Common Modes

The commonly used modes of the laser are mainly divided into four types:

• Mode 1: First pulse with suppression and indication light controlled internally.

• Mode 2: First pulse without suppression and indication light controlled internally.

• Mode 13: First pulse with suppression and indication light controlled externally.

• Mode 15: First pulse without suppression and indication light controlled externally.

The differences between these four common modes can be summarized into two points:

1. Internal control or external control.

2. First pulse with suppression and indication light. First pulse without suppression and indication light.

01 Internal Control

Internal control means that the laser's frequency and power coefficient (duty cycle) are generated internally by the laser, and the laser's output frequency and power can be controlled via the laser's host computer software or by sending serial port commands.

In internal control mode, the laser is set to output light at low voltage [i] and turn off the light at high voltage [ii] through the GATE interface by default when leaving the factory. Therefore, in internal control mode, if the GATE interface is floating, the laser can directly output strong light.

At the same time, in internal control mode, the laser's output light level can also be inverted by sending a serial port command (GTR=1), switching the GATE interface to output light at a high voltage and turning off the light at a low voltage.

[i] Low voltage is defined as 0-0.4V
[ii] High voltage is defined as 3.7-5V

02 External Control

External control means that the laser's switch and output frequency and power are determined by an external PWM signal. By adjusting the frequency and duty cycle of the PWM signal, the laser's output frequency and power can be controlled.

In external control mode, the laser is set to output light when the TRIG interface receives the PWM signal by default. Under constant frequency, the greater the duty cycle of the PWM signal, the greater the laser's output power. Additionally, it is necessary to ensure that the TRIG interface remains at a low voltage when the laser is off.

At the same time, in external control mode, the PWM signal’s high and low voltage duty cycle can be inverted by sending a serial port command (PTR=1), making the output power of the laser decrease as the duty cycle of the PWM signal increases. Again, it is necessary to ensure that the TRIG interface remains at a high voltage when the laser is off.

03 First Pulse Suppression and Indication Light

The first pulse and the laser's indication light have an inverse relationship. For example, in MOD13, there is indication light, but the first pulse is the smallest; in MOD15, there is no indication light, and the first pulse is the largest.

GATE and TRIG Signal Differences and Matching

01 GATE Signal

The laser's GATE signal corresponds to a TTL level signal, often referred to as the switch gate signal. By default, the laser is set to turn off at high voltage and turn on at low voltage.

There are only these two states in its operational mode: either high voltage or low voltage.

02 TRIG Signal

The laser's TRIG signal corresponds to a PWM pulse width modulation signal, often referred to as a repetition frequency signal. The PWM signal can be tuned by changing the pulse period and adjusted by modifying the pulse width (duty cycle).

The TRIG signal always has a periodic frequency in its working state. The greater the duty cycle, the greater the voltage. By default, the laser’s TRIG signal stores energy at a high voltage, with the light output occurring at the falling edge.

*INNO Laser is a highly trusted and closely partnered laser supplier for ARGUS laser marking equipment.