TSP #13 - Teardown and Operation of an Advantest TQ8325 Wavelength Meter 

I like how your plant looks like an antenna!

Good to see that EPROM and big tunnel like helium laser. Didn't expect stepper to run so fast though. Big electromechanical thing banging from inside!

At my grad internship I used to work with a spectrometer for measuring high power LED sources. Spectrometers plot the light spectrum from e.g. 300-900nm in 2048 steps. This device is clearly aimed for the use with 'pure' light sources. If I recall correctly, spectrometers use grating mirrors which reflect light where the reflection angle is a function of wavelength. This 'rainbow' is measured with a calibrated CCD sensor. Optical equipment is always very interesting to teardown. Nice video :)

good that you're uploading more videos the last time. keep it up!

It's hard to imagine why the stepper motor has to move continuously and so fast. Seems like it would wear slop into the slides over time. Many times in labs instruments are just left running continuously ... not the best practice, but it happens. I didn't expect to see that tube laser ... but it was 1985. Not sure the semiconductor lasers even existed then.

What a fascinating instrument. Nice walkthrough. Did you notice that the HVPS is datestamped in the mid 90s, 10 years after the other date markings? Repaired?

I looked up the number on the laser and found it was actually a Siemens (now LASOS) product. The motor on the sliding mirror is actually a brushless DC motor of the same type used in floppy disk drives.

Thanks for another great video.

Great video with that great instrument...

The ref laser source LGK-7634JT is actually made by Lasos company

I am bit surprised that they used motor for mirror moving (because of vibrations). I expected optics similar to cd laser (coils and magnets). I don't think elec. motor used to push-pull that big mirror is stepper. I think is simple synchronous electric motor used in floppy drives and 80's hard drives :) What are op amps used for detector? So, let's say that big mirror move 30mm and that light source is around 250nm, we end up with about 120000 pulses/motor rotation. Or it is 240000?

Thanks for the warning about the harmful effects of lasers and optical instruments.

I agree. I have taken apart a big Alcatel OmniSwitch, even the backplane hat quite a few bodge wires. So it was actually cheaper to have a person put those bodge wires in rather than re-doing a 16 layer board batch again. And I'm not even talking about those plug-in boards...

It seems to me that expensive, specialized equipment would be quite likely to be bodged. My reason for thinking this is that for the production of a low number of units, the added cost of bodging may be much less than the cost of a redesign process. Remember that the high price of these devices is primarily due to having to recoup the development cost over a small number of units, so the cost of any redesign can severely impact the end price of the product.

They're both correct. It's unclear, but I think he's saying that number is technically in terahertz, but the effective value of the digits that are changing are gigahertz, since they're in the thousandth fraction of the terahertz number (e.g. 0.001 Thz = 1 Ghz).

Thanks Shahriar for a walk around that amazing instrument. It must have cost a fortune in its time, with all those precision optics. Do you know if modern light frequency measurement tools still work on the same analog interference principles?

👍👍

What kind of signal frequency comes out of the detector? What amplitude is the raw signal from the photodiode? Might be cool if you could see anything with the scope! Also, whats with the protoboard sttle holes on the second board?

interesting the second board seems to have some kind of prototyping area on the right

Im kind of surprised that the optics and such are manufactured in Japan and not in Germany. I mean they are both awesome insane dudes but for some reason optics make more sense if they came from Germany. No pun intended there!

19:50 what a horrible board. In my opinion if you need that amount of bodge wires it is worth redesigning. especially for a unit in that price range.

you're barefoot ? that's cool

Hahaha man you are walking without shoes in this video hahaha isnt that dangerous given you are tearing down that kind of equipment? Haha