This video presents Part 2 of a teardown and examination of the Opgen Argus DNA Optical Mapping System, focusing on its intricate microscope components, laser system, and camera. The microscope features a high-precision XY motion platform with unique compliant motor couplings, a Nikon 60x oil immersion objective, and a barcode reader. A notable and elegant design element is a motorized fiber shaker that physically jiggles the laser's optical fiber to effectively reduce speckle caused by laser coherence. The internal PC hardware includes a dual-processor server motherboard, while a custom-designed, "ridiculously over-the-top" stepper motor driver board with an FPGA and DSP controls the motion. The camera, a Photometrics CoolSNAP EZ, includes a heavy vibration damping weight and a specific 562nm filter for fluorescence detection, but the presenter was unable to get it working. Despite the sophisticated engineering, the system's specialized nature, cumbersome size, and limited general utility lead to the decision to part out its components.
Detailed Summary of the Opgen Argus DNA Optical Mapping System (Part 2)
0:01 System Overview & Initial Boot-up: The video begins with an overview of the large Opgen Argus microscope system, which features a graphical vacuum fluorescent display (VFD) with burn-in. The Linux-based system takes several minutes to boot and uses a RAID controller. The presenter previously managed to boot to a password prompt and re-zero the XY axes, but this functionality is not demonstrated.
1:45 Internal Power & Laser: The system houses a standard PC power supply (Corsair TX850 later identified), a secondary power supply for motors, and a solid-state relay. A 532nm green laser with a fiber optic output (SMA connector) and its driver board are present.
2:42 Microscope & XY Stage Mechanics: The optical assembly is supported by a shock/vibration mount. The camera is located beneath, and the laser enters via a fiber at the top. A stepper motor likely handles focus. A barcode reader is integrated for plate identification. The system features a large Nikon 60x oil immersion objective, requiring oil between the lens and the sample. The XY motion platform utilizes high-precision IKO Japan slides with an interesting compliant coupling design to prevent lateral forces from motor sleds.
4:03 Unique Laser Speckle Reduction: A particularly intriguing feature is a motorized assembly with an offset weight that shakes the laser's optical fiber. This mechanism is designed to reduce speckle patterns caused by the laser's coherence, a technique the presenter later demonstrates effectively.
5:06 Internal PC & Camera Interface: The system's electronics are housed on slide-out trays, revealing an Intel S5520HC dual-processor server motherboard, presumably for intensive image processing. A Photometrics camera interface card, a RAID hard disk controller, dual serial ports, a graphics card, and Seagate Barracuda 1.5TB hard drives are also found.
7:23 Over-Engineered Stepper Motor Driver Board: A custom board is identified as a highly complex stepper motor driver, featuring 12 power op-amps for up to six motors (only three are used). It includes relays for interlocks (physically disconnecting motor outputs when covers are open), an Altera Cyclone FPGA, an Analog Devices Digital Signal Processor (DSP), and a Cypress USB 2 interface. The presenter expresses puzzlement at the extreme complexity for controlling just three stepper motors, suggesting off-the-shelf solutions would be more practical.
11:05 Photometrics CoolSNAP EZ Camera: The camera is identified as a Photometrics CoolSNAP EZ, an approximately half-inch CCD sensor. A heavy (~0.5kg) weight is directly attached to the camera, speculated to be for vibration damping or anti-vibration purposes. The camera's port has a 562nm narrow-band filter, designed to discriminate sample fluorescence from the 532nm excitation laser. It's a cooled camera (Peltier element) with a sealed enclosure and silica gel to prevent condensation, but not a full vacuum chamber.
14:10 Laser Functionality Demonstrated: The 50mW 532nm green laser is easily activated with a 24V supply and warms up in about a minute. The video showcases the fiber jiggler's ability to significantly reduce laser speckle, confirming its purpose. The laser module itself is sealed and kept in working condition.
15:52 Camera Malfunction: The presenter was unable to get the camera working, suspecting an issue with its control board (which includes a Freescale XC56 DSP and LVDS driver).
17:04 Parting Out Decision & Images: After testing the 60x Nikon objective with a DSLR, the presenter concludes its magnification is not ideal for general-purpose chip imaging due to its close working distance. Given the system's size, complexity, and limited utility, a decision is made to part it out and sell components on eBay. The video concludes by displaying several "squiggly wormy pictures" found on the system's hard drives, asking viewers for help in interpreting them.
Summary of YouTube Comments:
The comments largely confirm and expand on the technical insights shared in the video, with several recurring themes:
Speckle Reduction: Many viewers immediately recognized and praised the fiber shaker as a "mode scrambler" or "despeckling fiber jiggler." Explanations included changing light path lengths, continuously shuffling internal incidences of reflection, mixing fiber modes by bending, and blurring interference patterns for "slow" detectors. This feature was a significant highlight for many.
Over-Engineering and Cost: Commenters discussed the apparent "overkill" in design choices, such as the complex custom stepper motor driver board, heavy heat sinks, and extensive use of Allen screws. Some suggested this was due to "resume-driven design," meeting specific medical/lab equipment certifications (e.g., interlocks), or justifying the high price of the system. The rapid obsolescence of such expensive lab equipment was also noted.
Technical Details & Insights:
XY Stage: The IKO slides and flexure design were appreciated, with one commenter providing a detailed explanation of flexures and their advantages in high-precision mechanisms.
Camera/Laser: Information on Photometrics cameras (some being very high-end EMCCDs, though this one might be an interline CCD), the use of 488nm and 635nm lasers in similar systems, and 562nm being the emission peak for fluorescent green protein.
Linux/Software: Mentions of CentOS and suggestions for resetting the root password to access the system.
Vibration Damping: The large weight on the camera was largely agreed to be for vibration damping or shifting resonant frequencies, though some questioned its efficiency given the size.
General Appreciation: Many viewers expressed their enjoyment of Mike's content and teardowns, finding the device fascinating and the video packed with information.
Specific Inquiries: Some users asked for Mike's email for help, offered to perform forensic analysis on the hard drives, or inquired about specific parts for sale.
Humor/Observations: Comments ranged from the noise of parakeets in the background to comparisons with film (e.g., shark's head laser, DeLorean).