Yeast cells under the microscope

These bakers' yeast cells might be reproducing in the video. It's hard to tell if its just movement from the water under the cover slip

DIY Scanning Electron Microscope - Image Quality Improvements 3

A generous benefactor donated some proper SEM apertures to my project. These are much thinner than my brass plate in which I drilled a hole. This should increase resolution as there will be less scattering from the edges of my original, thick aperture plate









The main problem that I am having is that the oscilloscope X and Y amplifiers do not provide enough range or offset to easily control where the scan pattern hits the sample. I knew this would be a problem, so I included small mechanical X and Y stages for the specimen in the microscope. I even designed a vacuum-safe rotary passthrough into the vaccum chamber. The biggest problem is just connecting the rotary passthrough to the stage itself with a right-angle and/or flexible shaft arrangement. Space is very tight and the shaft must move with the stage, making for a difficult mechanical design.

DIY Scanning Electron Microscope - Image Quality Improvements 2

I've made some improvements to the microscope that have increased image quality somewhat. Here is a quick list of the changes:

-Made a new acrylic light guide that allows the scintillator to face the sample directly. The pipe is curved so that the light is directed upwards into the photomultiplier tube. The size of my bell jar necessitated that the PMT be mounted vertically, which is not good since a straight light pipe would cause the scintillator to be aimed directly at the bottom of the chamber.

-Added coaxial cabling and a fully-shielded box to the PMT amplifier circuitry.

-Adjusted PMT load resistor, and eventually installed a potentiometer so that I can change the load resistance to best match the raster scan rate

-Changed PMT amplifier circuitry so that the images are not inverted with respect to normal secondary electron micrographs



This is a MEMs gyroscope. I pried off the cover to expose the die.


This micrograph shows some structure on the die. Hopefully with better magnification and resolution, I'll be able to see the MEMs gyro itself.




It appears to me that the blurriness in these images is somewhat constant across all magnifications. This leads me to believe that focus is not the main issue, and that the problem is with PMT signal recovery. Scanning at a slower rate should help this, but the PMT amplifier is AC-coupled, so the scan rate cannot get too low, and I also cannot see the image on the oscilloscope at low scan rates -- making focus and various other adjustments difficult. I also haven't found a good way to synchronize my camera shutter to the raster scan.

Looking closely at CDs

I've always been intrigued by the dividing line between the written and unwritten areas on a CD-R. All CD-R formats begin writing in a spiral track starting at the inner radius of the disc and proceeds to the outer radius, so the inner area is written data, while the outer area is still blank. The inner area usually looks lighter in color.

I first placed the CD-R on the microscope stage, bottom-up. This worked at "medium power" 10x, but I could not focus at 40x because the thickness of the CD itself did not permit focusing the 40x objective. Instead, I scratched off a little of the protective coating on the CD top surface, then inspected it from the top.

This is a very old Memorex CD-R. Green-blue dye with a gold top-layer. I lit the CD-R from below with the microscope's built-in light. The image was pretty dark, but by setting the camera exposure to 3 sec, the final image looks great.

Here's a shot of the dividing line between the data area (upper half) of the disk and the blank unused portion of the disc (lower half). The length scale is approximate.



Here is a %100 crop from my camera. The length scale is approximate and computed by dividing the frame height of my camera (13mm) by the microscope objective's magnification (40x), then scaling in GIMP to make the bar an appropriate size for the crop. I checked Wikipedia, and it appears the track spacing for a CD-ROM is 1.6um, so I wasn't too far off.

Photomicography (microphotography) with Lumix GH1

UPDATE:
I bought a 2x achromatic objective for the microscope and also discovered that positioning the camera closer to the objective by removing microscope parts will increase the field of view (lower magnification). This is very useful since the 4x and even the 2x objective have too much magnification for large insects and similarly-sized objects.

I added photos of a large orb-weaver spider.



Since buying a Lumix GH1, I have been excited to attach it to my telescope, microscope, and any other imaging device so that I can capture unusual photographs. Today, I got all of the parts together and tested it with a microscope for the first time.

The microscope is a Labo VJ-71. It's a decent-quality student microscope with DIN 4x, 10x, and 40x objectives. I also have a remote shutter release for the camera, an LED on a flexible mount for top-lighting, and eyepiece (not needed for photography)



In order to attach the camera to the microscope, I found this microscope->Nikon adapter that I had built years ago. The barrel fits inside the microscope tube and provides a Nikon lens mount. I got the lens mount from a very old, very broken lens. I have a m4/3->Nikon adapter, so I can attach this to the GH1.

The first problem that I noticed was a bright, fuzzy spot in the middle of the image. I removed the camera, and looked down the microscope with all of the adapters in place, but no eyepiece. I could see a lot of light reflecting off the tube's inner walls and this ring of light was landing on the sensor and ruining the image. I added a washer to the Nikon adapter to act as a baffle. This helped, but I also ended up unscrewing the eyepiece tube from the microscope, and inserting the Nikon adapter into the microscope body. This shortened the distance between the camera and the objective, so there was less tube wall to cause unwanted reflections.
I started with this dandelion flower. This image is shot with my Vivitar 28-90, at 28mm


Here is a photo taken directly from the microscope. The objective is only 4x, but as you can see, the overall image is highly magnified. This cluster of pollen parts on the flower is only a few mm in width.

Another problem with microphotography is the extremely shallow depth of field. Even with the 4x objective, there is not much in focus. A neat solution to this problem is to use photo-stacking software, and stack a whole bunch of images taken at different focal depths.
I used CombineZM, a free software tool to do the alignment and stacking:
http://hadleyweb.pwp.blueyonder.co.uk/CZM/News.htm

Neat!


The head of a common house fly. Yikes!