So in short, there are actually 2 types of calibration, power and quality/distortion/coil/etc. of received data.
In long, resistors are responsible for power output of laser hence if laser is dying adjusting them will give results to some degree and in general is not advised to mes around unless you have oscilloscope and can actually interpret data coming out during this phase of calibration. Now secondly about quality, you see all lasers are not equal and there are some distortion in reading data, this data is stored in QR code and during manufacturing process while bench test each laser like focus/distortion/coil power etc this data is later read decrypted and added to chipset as binary data and encrypted again. There is much much more to this tale, however if you interested in this you can read about xbox360 drive it's a must for basic understanding and ps2 drive how to pair and calibrate laser unit with console. This has been widely explained in user friendly manner and is relevant to all laser drives. Attached file will give you some degree of complexities with resistors how it suppose to be done in any drive on example of ps2 laser.
laser playstation2.zip