jaydee, the point of a die sim is not to replicate a CPU. It is to apply, repeatably, heat to a DUT in the same shape and approximate heat load as a CPU. What is my laser proposal but another way to apply heat, repeatably, to a DUT? There are all manner of problems with heat die simulators.
1) The temperature measurement of the base of the DUT is an approximation at best and a stab in the dark at worst. The measurement is clouded by the TIM layer, and you must be joking if you try to tell me that the temp sensor embedded near the surface of the die is equivalent to the base plate temperature.
2) The DUT must be mounted using variable TIM. Are we testing the DUT or the TIM? If we're testing the DUT, why are we using TIM. To get the heat to the DUT. Is there another way to get heat to a DUT? Hence my discussion.
3) Losses. I don't care how much you characterize a die sim, there are still thermal losses in it. Heat leaks out all over the place.
A laser based sim would have advantages in all these areas:
1) The thermal sensor can be attached strongly to the base of the waterblock, and is not in the thermal flow path, so it should have an isothermal relationship with the waterblock
2) The DUT has heat applied directly to its surface, there is no question of variability of TIM.
3) Losses are easy to characterize with a laser system. It's possible to minimize them with reflective surfaces
Operating a device does not imply an understanding of it. I've met pilots who claim that an airplane flies because of the Bernoulli effect.
This is not the case. I'm not claiming that you don't understand, but I'm saying that practical experience with a device does not imply an understanding of its operation.
We're not trying to focus anything. That would be a mistake, as it would probably cut a hole straight through the DUT. The goal is to
spread the beam. This spread would have to be quantified, and calibrated. That's obvious.
Jaydee, please re-read my initial post. I covered probe placement in it.
For device cost, that was covered in another post of mine. 70W laser setups can be had between $5k and $10k. I saw 100W lasers at ~$12k.
The flatness of the base will cause 0 problems. If light is going to reflect, then the only change will the be angle it reflects on. I said before that it should be painted matte black to ensure full absorbtion. The flatness doesn't matter nearly as much as the cross-sectional area exposed to the beam. Which is constant, and determined by the lensing.
AFAIK the purchase of lasers is not restricted at all. The required optics to make them cause damage at range are... difficult at best.