Beware of "cheap repairs"

When we begin in 2005, we have been the only lab in the world for alternative Noritsu laser repair. But today there is a number of companies and few individuals who advertise similar services. All of them could be splitted on three groups:

• 1. Those who are our partners. They ship laser units to us.
• 2. Those who plays with second hand minilabs, scrapping them. They take gun from one unit, put to another one, and so on. We call them chess players. Sometime they are successfull, sometime no, but at least they can't spoil lasers, because they don't touch the things which they don't understand.
• 3. Few companies and individuals who perform repairs themselves. We can't talk about all of them, but such people mostly still learn the matter and stay at the same point, where we have been before 2008, walking again into the same water.

In fact every 8th to 10th laser we have here for repair came to us after unsuccessful attempts of repair. Looking on what and how other people do this work, we confirm that we are far forward from their experience. Our service is not cheap, right, other do cheaper. But we really do when the other people the only try to do. We decided to post below one reviewed example of such cheap unreliable repair, completed by unknown person February 7, 2010, and delivered to our lab April 24, 2010 for qualified repair.

Here is QSS30 laser unit Type B s/n A4900387. The owner informed us that he has got both GREEN and BLUE noise. Well, let us open this unit and understand whit's wrong with it? The electric current of BLUE laser diode is fine but 249 mA for GREEN is extremely low. Noritsu never put electric current less than 450 mA, because of possible risk of hindrances.

Here we can see the noise of BLUE laser (picture on the left) and GREEN laser (picture on the right) on the screen of analog oscilloscope:

Next step is to open the gun and look what part has been used to pump it? There is no surprise to see cheap poor quality LD instead of precise original part:

In fact cheap badly manufactured laser diodes can not be used in SLM (single longitudinal mode) laser guns, because such diodes have more than one peak near basic wavelength. Every such peak tries to build his own mode of coherent light creating a mess in chrystal area. This why finally we have got huge optical noise. First of all we have to put original LD instead of existing one to eliminate this problem:

We have got 542 mA (which is perfect for Green gun) after completion of all required calibrating procedures and checking the parameters of this particular LD:

Result is as doctor prescribed. Noise is no longer exist. Will do the same for Blue gun too.