Laser driver design puts safety first

[Les] From [Les’ Lab] Designed a driver for a laser diode up to 10 watts, and decided to show us how it works, what we should keep in mind when designing such a driver and talk about laser safety in general. This design is based on the LM350A, an adjustable current regulator capable of delivering power up to 10 watts at about 2 volts – which requires its diode. Such vague requirements are not easily met by commonly available PSUs, which is why a custom design was called for.

He told us how he approached us to plan the stability of the current regulation circuit, the requirements of the PCB design, and the user interface for such drivers. However, this is only part of the battle – it is important to control the current properly, but to minimize the risk of accidental injury. Thus, he talked extensively about designing driver circuits with safety in mind – using a variety of interlocks, such as a latching relay circuit to prevent power from being applied as soon as it is applied.

Showing the front panel of the laser driver, voltmeter display, laser connector, three LEDs for operation mode, a dial to adjust the current and a key switch.Of course, safety concerns go beyond the characteristics of the driver, and so on [Les], Feeling that we should know what goes into such a laser handling of energy. He explains the importance of choosing appropriate safety glasses for the wavelength involved – what the different relevant numbers mean and how to use these numbers to choose the glasses that can protect you from being blinded in an accident. It is also said to mount everything tightly – you don’t want the laser to accidentally move away from the way you want it to shine, because even reflection can be quite dangerous.

In the end, [Les] Shows the driver in action with a laser diode and generates enough smoke that we are legally obliged to consider it a ‘smoke test’ – a success! He has big plans for those diodes and we can’t wait to see them succeed.

[Les]Its YouTube channel has videos on all types of electronics-related DIY builds, and if laser-related topics are of interest to you, it’s a must watch. We’ve covered a few of its builds in the past, including a raspberry pie-based spectrometer and a high-voltage switch from a simple spark gap.

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