Category Archives: Other science

aka stamp collecting

Moving in Stereo

Posted on by

Life’s the same, except for my shoes

Stereograms! Make Your Own 3D Camera for $15 or Less

If you happen to have two digital cameras, you can skip some of the steps, like getting the film developed and scanning the pictures. I was able to get my hands on a second camera; I found that butt-end joining got the lenses close together. I also tried side-by-side, using some optics posts and attaching to the camera tripod mounts. Unfortunately I did not have a third camera, so I can’t show the full rig.

Here is a laser table stereogram. I tested this on a few people, and not all could get it to work. But I can, and that’s good enough, for I am the benchmark for many things.

Tips for 3-D “cross-viewing”

Also, you can see that the two pictures appear to diverge from each other, an example of the leaning tower illusion

Deeper Than it Looks

Posted on by

My recent post on Haidinger’s brush reminded me of another optical phenomenon I have observed, and one that is a bit easier to see: the Pulfrich effect.

The Pulfrich effect is a phenomenon that gives the illusion of depth based on the response time of different light levels in the eye and how the brain interprets the delay. Lower light levels take longer to process, so if the image viewed by one eye is dimmer than the other, the signal from the dimmer view will lag in reaching your brain to be interpreted. With one eye darkened, something moving across your field of view will appear to get closer or further way.

When I first read about this, I consulted Wikipedia, which tells me

In the classic Pulfrich effect experiment a subject views a pendulum swinging in a plane perpendicular to the observer’s line of sight. When a neutral density filter (a darkened lens – typically gray) is placed in front of, say, the right eye the pendulum seems to take on an elliptical orbit, appearing closer as it swings toward the right and farther as it swings toward the left.

Well, gee, I work in an atomic physics lab. I can make a pendulum and have neutral density filters, so I went ahead an made up the experiment, using some scrap wire and a few optical-mount bases for the pendulum. And sure enough, with the right combination of filters (I think I ended up with ND=0.3 or 0.4) I was able to easily see the effect — the pendulum’s oscillation got closer at one end and further away at the other, and it reversed itself when I switched and darkened the other eye.

I wanted to show this off, so to make things a little easier I salvaged a damaged pair of sunglasses and popped one of the lenses shades out. (Not really lenses are they? OK, pedantic man says they are, albeit with an infinite focal length) That covers the eye better than the ND filter, which only has a 1″ diameter. I can use either the free eyepiece or the glasses. The biggest problem is getting people to look with both eyes — their natural tendency is to shut one eye and only look through the shade.

Got Bamboo?

Posted on by

We need some.

National Zoo Runs Low on Bamboo Supply

The bamboo on the zoo grounds is annually cut back and usually regrows, the zoo said. This year, for reasons unknown, the normally tenacious species did not grow back.

As a result, more needs to be found.

I’ve run across some small bamboo stands while geocaching. The first time it was a surprise, to be hiking along and then find myself in the midst of a dense jail of green bars.

Meanwhile, Over on the Hill …

Posted on by

Notes from Steven Chu’s Senate confirmation hearings

“Will you take a lead, not just to talk about it, not just to opine about it, but actually do the things necessary to see if we can’t restart our nuclear industry?” asked Senator Jeff Sessions of Alabama. Tennessee Senator Bob Corker echoed the question later, asking Chu if he meant to “pursue nuclear now… all out now?”

Yes, yes, and yes, Chu replied. “Nuclear power is going to be an important part of our energy mix,” he told the committee, a position he has stated before. Chu noted that nuclear power provides 70% of the carbon-free electricity in the country. Still, he said it was important to continue researching better waste disposal and fuel recycling technologies, perhaps in collaboration with other countries.

One Spookfish Was Harmed in the Making of this Paper

Posted on by

Spookfish Sees Things Like Nobody Else Ever Has

Of all the animals in the world, the lowly spookfish has the oddest eyes — compound mechanisms that bear more than a passing resemblance to rearview mirrors.

The bottom half of its eyes point upwards. The upper half point downwards, and are backed with a layer of reflective guanine crystals that bounce a focused image into the retina.

The titular disclaimer comes from reading this:

Researchers tested the eyes by taking flash photographs from above and below a live spookfish, then dissecting its eyes.

(there’s also this article)

We Lost … to Mathematicians?

Posted on by

Doing the Math to Find the Good Jobs

The study, to be released Tuesday from CareerCast.com, a new job site, evaluates 200 professions to determine the best and worst according to five criteria inherent to every job: environment, income, employment outlook, physical demands and stress.
[…]
According to the study, mathematicians fared best in part because they typically work in favorable conditions — indoors and in places free of toxic fumes or noise — unlike those toward the bottom of the list like sewage-plant operator, painter and bricklayer. They also aren’t expected to do any heavy lifting, crawling or crouching — attributes associated with occupations such as firefighter, auto mechanic and plumber.

Physicist ranks 13th, presumably because we experimentalists get to play with dangerous things, which I consider a perq. At least we beat out Astronomer; I suppose that’s because they have to work nights.