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Two mirrors, actually.

New question: can anyone think of any reason why the height of the laser above the surface would matter? I ask because I am in the process of constructing the LSS for regionals and with the materials I have it would be much simpler if I set the laser at 5 cm instead of 2 cm. Since it deviates from spec I would have to inform teams in advance, but can anyone think of a reason why it would actually matter?

Flavorflav wrote:Two mirrors, actually.

No, one mirror. You have to bounce the laser from one wall onto the target using one mirror.

Flavorflav wrote: New question: can anyone think of any reason why the height of the laser above the surface would matter? I ask because I am in the process of constructing the LSS for regionals and with the materials I have it would be much simpler if I set the laser at 5 cm instead of 2 cm. Since it deviates from spec I would have to inform teams in advance, but can anyone think of a reason why it would actually matter?

I don't really know, it's probably just a conformaty thing. Easier if all of them are exactly the same...

robodude wrote:

Flavorflav wrote:Two mirrors, actually.

No, one mirror. You have to bounce the laser from one wall onto the target using one mirror.

It's one mirror for Div B, two mirrors for Div C. Apparently Div C isn't hard enough as it is.

I'm in optics!

DiscoLava wrote:I'm in optics!

Congratulations!

So I was able to check out a calculator from my algebra teacher the other day. It's a really good programable calculator, which I intend to use since the use of any calculator is allowed.

However, while typing in a few different programs, I realized that I don't fully understand the difference between the Focal length, the Front Focal Distance (FFD) and the Back Focal Distance (BFD)

Can someone help clarify the differences please?

robodude wrote:So I was able to check out a calculator from my algebra teacher the other day. It's a really good programable calculator, which I intend to use since the use of any calculator is allowed.

What kind of calculator is it?

robodude wrote:So I was able to check out a calculator from my algebra teacher the other day. It's a really good programable calculator, which I intend to use since the use of any calculator is allowed.

However, while typing in a few different programs, I realized that I don't fully understand the difference between the Focal length, the Front Focal Distance (FFD) and the Back Focal Distance (BFD)

Can someone help clarify the differences please?

Generally, lenses have two sides, each of which is a section of the surface of a sphere. A sphere is defined by the length of its radius. So if the front side of the lens is a section of a sphere with a radius of 50 cm, then the front focal distance is 50 cm. The front side can be either concave or convex. You must define a sign convention for your front focal distance for the equation, so that one is positive and the other is negative. Same for the back focal distance.

Every lens either bends light inward or outward. So, if you send a beam of collimated (unidirectional) light into a given lens, either all the rays will converge on a single point, or they will bend away so that they diverge from a single point. That point is a certain distance from the lens, known as the focal length of the lens. Again, you must define a sign convention for concave or convex. If you find a version of the lens maker's equation in a textbook or other resource, it should tell you what sign conventions to use for that equation.

ichaelm wrote:

robodude wrote:So I was able to check out a calculator from my algebra teacher the other day. It's a really good programable calculator, which I intend to use since the use of any calculator is allowed.

However, while typing in a few different programs, I realized that I don't fully understand the difference between the Focal length, the Front Focal Distance (FFD) and the Back Focal Distance (BFD)

Can someone help clarify the differences please?

Generally, lenses have two sides, each of which is a section of the surface of a sphere. A sphere is defined by the length of its radius. So if the front side of the lens is a section of a sphere with a radius of 50 cm, then the front focal distance is 50 cm. The front side can be either concave or convex. You must define a sign convention for your front focal distance for the equation, so that one is positive and the other is negative. Same for the back focal distance.

Every lens either bends light inward or outward. So, if you send a beam of collimated (unidirectional) light into a given lens, either all the rays will converge on a single point, or they will bend away so that they diverge from a single point. That point is a certain distance from the lens, known as the focal length of the lens. Again, you must define a sign convention for concave or convex. If you find a version of the lens maker's equation in a textbook or other resource, it should tell you what sign conventions to use for that equation.

So the FFD and BFD have nothing to do with the focus?

robodude wrote:

ichaelm wrote:

robodude wrote:So I was able to check out a calculator from my algebra teacher the other day. It's a really good programable calculator, which I intend to use since the use of any calculator is allowed.

However, while typing in a few different programs, I realized that I don't fully understand the difference between the Focal length, the Front Focal Distance (FFD) and the Back Focal Distance (BFD)

Can someone help clarify the differences please?

Generally, lenses have two sides, each of which is a section of the surface of a sphere. A sphere is defined by the length of its radius. So if the front side of the lens is a section of a sphere with a radius of 50 cm, then the front focal distance is 50 cm. The front side can be either concave or convex. You must define a sign convention for your front focal distance for the equation, so that one is positive and the other is negative. Same for the back focal distance.

Every lens either bends light inward or outward. So, if you send a beam of collimated (unidirectional) light into a given lens, either all the rays will converge on a single point, or they will bend away so that they diverge from a single point. That point is a certain distance from the lens, known as the focal length of the lens. Again, you must define a sign convention for concave or convex. If you find a version of the lens maker's equation in a textbook or other resource, it should tell you what sign conventions to use for that equation.

So the FFD and BFD have nothing to do with the focus?

Actually they do, as per the lensmaker's equation. The focal length is determined by several variables: FFD, BFD, refractive index, and thickness.