Frequently asked questions

If you have any additional questions not answered below, please feel free to email us or give us a call!

•• Are laser diode systems polarized? If so, what type of polarization?
All of Power Technology's systems are linearly polarized. Index guided diodes typically have a polarization ratio between 50:1 and 100:1. For wide stripe diodes, the polarization ratio is typically 30:1 or greater. Our diode-pumped Nd:YAG systems have a ratio of 100:1.

•• On systems with line generators, what is the thickness of the line?
Typically, the thickness is 1mm at 30.5cm [12 inches]. However, the thickness can be altered to meet your needs.

•• Why would I want to order a 635nm laser when 670nm is cheaper?
If the system you are building is intended for viewing by the human eye, 635nm will appear approximately five times brighter than 670nm at the same output power. Likewise, several of our diode-pumped Nd:YAG laser modules and systems emit at 532nm and appear much brighter than even 635nm at the same power. Because of their apparent brightness, these systems are widely used in medical applications whereby only a small amount of laser radiation can be pointed into the human eye.

•• What is the exit beam size for the optical system?
For circular beams, the diameter is between 1mm and 4mm, depending on the optics. For elliptical beams, it ranges from 0.3mm x 1.3mm to 1.9mm x 5.5mm.

•• What is the beam divergence?
Beam divergence varies widely depending on the laser diode system and the optics used within the system. Ask your sales representative which lens is best for your specific needs.

•• What is the wavelength stability for either the APM or PPM?
Both modules can maintain wavelength stability within 0.15nm, and both can tune the wavelength to a maximum of 7.5nm below and 3.0nm above the diode manufacturer's specified wavelength.

•• What is the temperature stability for either the APM or PPM?
Both modules can maintain temperature stability within 0.5°C. They also can adjust the diode temperature 25° Celcius below and 15° Celcius above the case temperature.

•• Why does the output power of my line generating laser module measure only a fraction of what I ordered?
The total power of the laser is spread out all along the line. Power measurements are taken through a 7mm aperature and only capture a small part of the laser's power. To measure the total output power from a laser with a line generator, the measurement must be taken with an optical power meter coupled into an integrating sphere.

•• Who is CDRH, and what does it do?
CDRH (Center For Devices and Radiological Health) is a division of the FDA (Food and Drug Administration) that regulates all radiation-emitting products in the USA. The address is

See our safety page for more information, or visit CDRH on the Web at http://www.fda.gov/cdrh/.

•• When I vary the input voltage on one of your laser modules, why does the optical output power remain the same?
Power Technology builds its laser modules for a wide range of input voltages. The internal voltage regulation designed into the modules will provide constant power to the laser over the specified operating voltage range.

•• What type of power source should I use with your modules?
The correct choice of power supply depends on two things: your application and the type of laser module you have. In addition to choosing the correct voltage, make sure that the supply you select is rated to provide the amount of current required by the module. You can find the maximum current rating for each of our laser modules on its respective specification page within this site. For OEM applications, a power source is generally readily available. If one is not available, we suggest the use of a linear type power supply, such as those manufactured by Power-One. These power supplies are readily available in most Digi-Key catalogs or from your local electronics parts supplier. Switching power supplies are not recommended for several reasons. First, the unstable nature of some switchers at very low currents can potentially blow the diode. Second, switchers are not as quiet as a linear power supply and may introduce noise into the laser. If your application does not require integration into a product, you may want to use a battery or a regulated wall transformer to supply the power you need. One brand of wall transformer that works well for us is CUI STACK, available in most Digi-Key catalogs. For laboratory use, PTI recommends a bench-top power supply. Several companies have proven to provide a good quality power supply, most notably Agilent (formerly Hewlett Packard).