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Posts tagged ‘optics’

Laser Optics Demonstrator

There are a fair number of Laser Optics kits for classrooms on the market, but most of them are design for only  a few purposes in demonstrating the properties of optics, lasers, and the like. The United Scientific Laser Optics Demonstrator works as a comprehensive optical demonstration system.

2474large The core of the Demonstrator is a built-in He-Ne (Helium-Neon) laser. Unlike budget systems that may use a LED Laser (which can produce square shaped target dots). In addition the set includes a deflection system, ray optics board, and 30 optical quality glass components on carriers, three magnetic base supports and mechanical stage for wave optics.

The He-Ne laser is mounted horizontally in the demonstrator and the beam is diverted up towards the five mirrors. Each of these mirrors is only partially aluminized  so that a fraction of the beam is deflected onto the white optics board to create a ray bundle. 2474a

On the white board is a 360 degree graduated table for measurement.  The table has a knob on the back of the board so that it can be rotated. In the dead center of the table is a mount where the various glass optical components can be mounted – Demonstration lenes (convex, concave) prisms, mirrors and other optical instruments.  Fiber optics are also included.

In addition to these optical ray systems the Laser Optics Demonstrator can be used for several light wave experiments. The base holds the various magnetic base supports that are included with the demonstrator. These components include lenses, polarizers, an air wedge, bi-prism, interference apertures, obstacles. Many interferenc2474be  and diffraction experiments can be performed with these components.  The laser is bright enough that most experiments can be held in a bright room, but extended patterns or diffractions may require darkening.

The entire Laser Optics Demonstrator comes in a metal carrying case that measures 15″ x 15″ x 13″.

Want to buy the Laser Optics Demonstrator?

Want to buy other Advanced Physics Classroom Equipment?

www.spectrum-scientifics.com

 

Glow Crazy Pattern Painter

Glow Crazy has been a nifty product we’ve carried for several years. It is a simple concept where kids can paint with light on a glowing canvas that fades over time.  The Glow Crazy Distance Doodler and the Doodle Dome have been popular products in this line. Now another entry has come into the product line – the Glow Crazy Pattern Painter

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Jr. Scientist Series Part 2 – Crystals and Telescopes

We covered some of the Robotic Jr. Scientist series in part 1. In part 2 we cover a couple of other parts of the new Jr. Scientists series one involving crystals and the other involving making your own refracting telescope.

Crystal growing has long been a part of kids chemistry experiments. It is fun to watch the crystals grow over time and there have been plenty of kits available for crystal growing, but when we saw the Jr. Scientist version we had to give it a try!

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The Lies Magnifier Makers Tell, Part 2 – Progress

We’ve complained about this in a previous blog post. Magnifier manufacturers have been telling some rather big whoppers about the magnifiers they make. Some have been claiming to have 30X power (which is in the microscope range) while having lenses almost an inch across. This is simply not physically possible. For a while it seemed like it was inevitable that it would only get worse – mind the products were good, but the specs were lying, a lot.

But from one of our suppliers we recently received this message in the mail

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Koontz! Funs new Science Kits Part 2

So we already covered the Catapult, the key lock, the Kaleidscope, and the Rolling boomerang in part 1.  Now for the rest of the Koontz line:

First up is the Merry-Go-Round:

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This model you put together and the gears operate the spinning discs! A nifty demonstration of cetripital force!

Next up is the Clock

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This is not an operational clock, but it does show how gears are used so that the hour hand moves as you rotate the minute hand. An excellent demonstration of gear ratios!

Next we have the Koontz Safe

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Here you build the safe and set the combination lock. Then you can see how you need to turn the dials just right to open the lock!.

Finally, getting back to the world of optics, we have the Periscope!

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With the included two mirrors and the frame you build you can construct a device that lets you see over walls, around corners and other locations! See without being seen!

www.spectrum-scientifics.com

 

First and Second Surface Mirrors

Mirrors are part of most people’s everyday life, from the bathroom mirror, to a car’s rearview mirror, and so on. What most people may not realize is that there are more than one type of mirror, or at least more than one way for a mirror to be silvered.

Most mirrors people use on a daily basis are what are called second surface mirrors. This is where the back of the mirror is coated with the reflective material. This lets the glass protect the reflective coating so that it does not get damaged. Since the reflective coatings are actually quite fragile second surface mirrors are used anyplace where they might be exposed to weather, people’s fingers, and so on. The only problem is that in order to be reflected, light must pass through the glass to strike the reflective material in the back. Since this means the light is traveling through the glass, it gets refracted (bent) just a bit. There is also some loss of light from the light hitting the glass. For most daily use this it not very important. After all, we are just trying to shave, put on makeup, or checking to see if the lane next to us is clear. We’re not taking accurate measurements in a lab when traveling in our car (or at least we shouldn’t be!)

But when using a more advanced instrument, such as a telescope, that  distortion and light loss can be crucial. So almost all reflecting telescopes (and more advanced optical systems) use First Surface Mirrors instead. On a first surface mirror the reflective coating is put right on top of the glass instead of behind it. This means there is no distortion from the glass (as long as the glass surface is properly shaped) and no loss of light. The difference can be quite dramatic. A Second Surface Mirror reflects only around 80-85% of the incoming light (sometimes less) while a First Surface Mirror typically will reflect 94% to as much as 99% of the incoming light, depending on the coating.

There is a price, however: First Surface Mirrors are very vulnerable to the elements. Just touching them with your finger can damage the delicate coating, and while a telescope may be used outside, it should not be left there or left exposed with its dust caps off when not in use. A big issue with solar energy researchers who want to concentrate light with mirrors is that they would like to use the more efficient first surface mirrors but need coatings that can reflect the light and survive the elements. Some additional coatings can be added on top of the mirror to strengthen them but not effect their optical quality. Even without exposure to elements sometimes some damage can creep into a first surface mirror around the edges over the course of a few years.

The way to tell the difference between the two types of mirrors is to touch them gently with a pencil tip. If the tip seems to touch the reflected tip it is a First Surface Mirror, if there is a gap it is a Second Surface Mirror.

A note about mirror coatings: Many folks refer to the coatings a ‘silvering’ and this dates back to the days when mirrors were actually coated using silver. But silver is expensive and prone to tarnishing, even in Second Surface Mirrors (you can see this in many older mirrors). Most mirrors made today are coated with aluminum, which does not tarnish. There are some mirrors coated with silver these days, but this coatings are used because silver is excellent for reflecting infrared light.

A final note about so-called ‘1-way mirrors’, the favorite of cop-drama interrogation rooms and the people who watch focus groups in action. Strictly speaking there is not really such a thing as a one way mirror. What is used is a window with a mirrored coating that reflects much of the light, but not the majority. These actually only work when the light in the room with the ‘mirror’ side is more brightly lit than the observing room. If you watch the cop-dramas you may notice this is one thing they get correct as the observing room is kept rather dark. If you were to light up the other room the “one-way mirror” would act merely as a poor window.

Spectrum Scientifics

3D Lenticular Motion Bookmarks!

This is a product that we admit there were some doubts about, but it has actually shown itself to be a very popular item: A series of rulers and bookmarks that have high-quality 3D lenticular images that appear to move!

3D Lenticular Bookmark!

Sadly, these pictures cannot really do these things justice. So for that we have a video of our display unit:

As you can see from the video, these are not the lenticulars of yesteryear where you would have only two or three ‘scenes’. In this case there are enough images to make it seem like the animals are really walking (or climbing).

You can also  see from the video there are more than just penguins. Another popular model is the Gears & Robots

The Triceratops is also popular:

We also have them in larger sizes: The 12″ rulers (the above are 6″ Rulers/Bookmarks) are quite popular, such as the Walking T-Rex 12″ Ruler

These lenticular 3D Rulers/Bookmarks make great gifts and add a little fun to the ordinary bookmark!

KOLA Phone Camera Accessory

Phone cameras are probably the most used type of camera these days. You just can’t beat the sheer convenience of having a high-resolution digital instrument fitting neatly in your pocket -and one that serves another purpose as well. Now sure, they will never match the versatility of devoted cameras or the optical powers of a Single Lens Reflex camera, but they were never meant to match those tools, just let folks have a powerful instrument in their pockets that they would carry normally!

Still, phone cameras do have many limitations. All their image changing is digital, not optical.  They lack any real accessories.

But that doesn’t mean you are without options. In fact one new item, the KOLA Phone Camera Accessory is designed to give a little pizazz to your camera phone and it goes right on your keychain! KOLA stands for Kolor of Light Accessory, and it is made up of eight durable color gel filters that can easily be put in front of your camera phone’s lens to make your shots much more interesting!

KOLA Camera Accessory

KOLA Camera Accessory

We tried this with our own camera phone – A Droid HTC incredible. We set the resolution low to keep the bandwidth down, but you’ll get the idea. First we took a control picture:

No Filter

Then we started with the yellow filter since it was a light filter:

With Yellow Kola Filter

How about one of the darker filters, such as the Red Filter. It send the camera’s digital aperture into a tizzy:

Next time we should hold it back aways from the lens.

How about Purple? Purple is fun!

We took the blue filter and held it a few inches away from the camera lens so it covered about 1/2 of the view:

All of these shots were taken over a period of about 5 minutes and were more a case of fooling around with the KOLA than any serious photo study. But these few photos can give you an idea of the possibilities available when you keep a Kola on your keychain!

The Lies Magnifier Manufacturers Tell…

Every now and then we get a customer in the store who wants a very high power magnifier. Sometimes they bring printouts from other retailers that show some rather….unlikely high -power magnifiers with powers of 20x, 30x, even 50x. We unfortunately must inform them of the truth of these claims. The fact is – what is printed in the copy or actually on the magnifier is not true.

Oh, its not really the other companies fault – they are just going with what they see on the box and on the product. A typical example is this magnifier:

An Example of a mis-listed magnifier

Don’t you believe it!

You’ll note this has a rather generous 30x magnification, which still having a nice, wide 21mm lens width.

Nonsense! The rules of optics are remarkably clear on this – the simple fact of the matter is that the more powerful a magnifier is (the higher its magnification) the short its focal length (the point where light rays passing through the lens meet on the other side of the lens) must be! And the shorter that focal length, the smaller the magnifying lens will be.

Let us elaborate:

A large handheld magnifier that probably everyone has in their drawer only provides about 2-3x and so has a long focal length of about 10″. Focal length equates to something known as ‘working distance’. What this means that you can use the magnifier about 10″ away from the thing you are viewing (this will vary slightly).

However, as you increase the magnification of the lens, the focal length of the lens must be made shorter – this also means the diameter of the lens must also shrink or else your lens will become excessively thick and will have a distorting shape – think of looking through a crystal ball and how messed up that image is. Its a good example of a wide diameter lens with a very small focal length (a ball lens, ineffect).

What this means is that by the time you get to just 10x magnification, your lens is barely over a 1/2″ in diameter. This triplet lens we sell is a good example:

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The diameter is just 18mm on this unit, and in order to avoid image distortion the lens is a triplet design – where three lenses are placed together to make a much better image than one lens alone would provide. As you can see, the higher power we go, the smaller the lens is going to get. In reality, our 30x lens shown up top should really be about 4-5mm in diameter. Not a very big lens at all.

Truth to be told, barring some optical tricks (which I can assure these ’30X’ magnifiers do not employ) most magnifiers rarely go above 12-15x in power. That realm is reserved for low powered microscopes, which are a different optical beast altogether.

Unfortunately, big numbers sell, and so manufacturers keep putting unrealistic figures on their products knowing that most people won’t know any better. The real tragedy is that most of these overplayed magnifiers are not bad products! The 30X magnifier shown above is actually a decent 7-8X loupe magnifier. We’re even guilty at Spectrum of carrying a few of these ourselves – but in our product copy we note that the listed magnification is probably not accurate. We wish we didn’t have to do that, but we don’t like lying about a magnifier’s true abilities, we don’t like discarding a decent product, and our complaints to the manufacturer have fallen on deaf ears.

So remember these words when you are looking for a high-power magnifier. Don’t get suckered in by inflated claims and be realistic about what your lens can do!

Want to buy magnifiers?

www.spectrum-scientifics.com