Hamamatsu develops diode-pumped pulsed laser that delivers 117J

01 May 2019

Helium-cooled source suited to industrial applications, promising “new areas of laser processing,” says firm.

Hamamatsu Photonics has established a technique for efficiently helium-cooling a laser medium and consequently developed an industrial pulsed laser system that produces a pulse energy of 117 joules. The company says this output is “the world’s highest among laser-diode-pumped lasers.”

This newly developed laser system made its public debut last week at the International Congress on Optics & Photonics 2019 (“OPIC”) held in Pacifico Yokohama (Nishi-ku, Yokohama, Japan). Hamamatsu commented that the new source is set to “further enhance the laser peening effect for hardening the surfaces of metal materials used in aircraft and automobiles.”

“This laser system will also prove a powerful assist for new laser processing applications such as laser forming for shaping metal materials and paint removal.”

Explaining some of the laser’s design features that have enhanced laser output energy, Hamamatsu said, “Our newly developed laser has vastly improved cooling efficiency achieved by circulating helium gas through the laser amplification chamber, which cools both sides of the laser medium."

Stable cooling

The technical description continues, “The helium gas is maintained at a pressure of 5 atmospheres and a temperature of -100 degrees Celsius for stable cooling. Moreover, in the optical window through which the laser passes, we employed a material resistant to low temperature and high pressures as well as a structural design with high durability.”

To make the laser medium store more energy with higher efficiency than conventional devices, Hamamatsu designed large-diameter ceramic discs optimized to easily absorb light and incorporated six of these discs as the laser medium.

“We also developed a unique amplifier design while mounting our compact yet high power LD modules as pumping sources and in this way succeeded in downsizing the system. This means we can now provide a LD-pumped pulsed laser system capable of producing the world’s highest output energy, even with a device footprint equivalent to LD-pumped pulsed lasers developed overseas.”

The new laser system was developed by the Research and Development of Next Generation Laser Processing Technology project, supported by the New Energy and Industrial Technology Development Organization, a national research and development agency in Japan.

Market pull

“Pulsed lasers with an output energy of around 10 joules are starting to appear on production lines,” added Hamatsu’s launch statement.

“For these tasks there is now increasing demand for higher energy pulsed laser systems that can irradiate a wide area and apply a shock wave deep into materials to further boost the laser peening effect.

“Our newly developed laser is an industrial pulsed laser system capable of boosting the pulse energy of seed light of 5 joules up to 117 joules by using two amplifiers, each equipped with four pumping LD modules that we manufacture in-house.”

The company concluded that it will continue developing new laser media and cooling techniques to further boost the laser output energy: “In cooperation with the TACMI Consortium and, along with member companies and other companies involved in laser processing, we will open up new laser processing applications by continually creating practical laser processing technology.”