Thanks mawyatt for all your input!
You are right that we can´t discuss the whole background here but you gave me some very interesting points to think about.
Your Mitutoyo seems to be a very nice lens but it´s also very expensive!
![Grin ;D](https://www.eevblog.com/forum/Smileys/default/grin.gif)
As magic explained it´s very important for us to get these nice coloured pictures which is possible with a "cheap" DSLR if you put your light behind the die and let it bounce back from the lens of the objective. Sound crazy for a normal photographer but it works well after some trial and error.
But perhaps I can mix the the microscope lens with the right illumination... ![Cool 8)](https://www.eevblog.com/forum/Smileys/default/cool.gif)
...I know it´s "not possible" to get a resolution of 200nm with normal light, it was more a theoretical figure... ![Wink ;)](https://www.eevblog.com/forum/Smileys/default/wink.gif)
Yes the Mitutoyo's are somewhat expensive, but worth it if you do this type of imaging a lot. I wouldn't recommend starting with one, but later you'll probably end up with 1 or 2...maybe more
![Roll Eyes ::)](https://www.eevblog.com/forum/Smileys/default/rolleyes.gif)
Some Nikon's are really good also.
Later you will also find you'll want something that's really good around 1~2X, much better than standard macro lenses, something that can out-revolve say a Nikon D850 at 1X
![Shocked :o](https://www.eevblog.com/forum/Smileys/default/shocked.gif)
The Mitiutoyo's below 5X aren't the better choices. Nikon produced some superb film reproduction lens (think these were for motion picture film replication) called Printing-Nikkors, the 105mm F2.8 version is a brilliant optical design, but are rare and expensive. Another lens that's found repurposing is the lens from an old Minolta DiMage 5400 scanner, when setup properly this lens is really good from 1.5~4X. It's price has jumped since other folks are finding out about it.
https://www.closeuphotography.com/minolta-dimage-scan-elite-5400-lensRobert's site is a wealth of information on lenses and such.
https://www.closeuphotography.comIt's kinda fun to construct a lens from surplus/scrap parts and end up with a jewel of an overall lens assembly for studio macro use (reminds me of getting a couple Tektronix 2465 scopes off eBay and fixing them, same for a couple HP34401A DVMs), there are lots of options to about ~5X but then you start wanting the Mitutoyos for 5X and beyond.
Please keep posting your beautiful chip images, really enjoy seeing these masterpieces of silicon displayed is such wonderful fashion.
Got to finish up my voltage reference design built around the LM399, which your images and detailed circuit were superb and very helpful!!
![ThumbsUp :-+](https://www.eevblog.com/forum/Smileys/default/icon_smile_thumbsup.gif)
I had created a SPICE model for the LM399 and also a 6.2V Zener with NPN (2N3904), had to "tweak" the LM399 resistors to get the temp curve to look OK, but after seeing your image and schematic understood why things needed changing.
One circuit you might be interested in is a ultra-precision voltage divider that doesn't require precision components. If you use a CMOS FF and tie resistors between the Q and Qbar output, the center of the resistors is shunted to ground with a filter cap. The center voltage will be exactly 1/2 the CMOS FF Vdd voltage independent of the 2 resistor values, they don't even have to match!! What's happening is the Q and Qbar resistors from a simple voltage divider, say Vdd(R1/(R1+R2)), where R1 is tied to Q and R2 to Qbar. On the next clock edge Q and Qbar swap state and now the voltage divider is Vdd(R2/(R1+R2)). The capacitor averages these two voltages to exactly 1/2 Vdd. In real life the small Rdon of the NMOS and PMOS comes into play but can be swamped by R1 and R2 values, or use paralleled inverters on Q and Qbar outputs. This can produce results around a ppm with 1% resistors
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
We patented (5030848) this concept way back and used it in numerous designs, but the patent has long since run out.
If you have a 74AC74 or other FF and a 74AC04 or other inverter CMOS parts, and a couple 10K, 50K or 100K, or just about any resistor value and any cap. Just clock the FF at say 1~10KHz and supply 5.00000 volts as Vdd, then measure across the cap. You will get something like 2.49999 volts once you factor the DVM impedance with the Thevin eqv. impedance from the voltage divider. You can change one of the resistor values by 1~20% and output won't change!!
![Shocked :o](https://www.eevblog.com/forum/Smileys/default/shocked.gif)
Of course you can buffer the result with an op-amp (which we usually did) for lower output impedance.
Anyway, a fun little circuit you can put together on a plug-in board.
Best,