Optical Training Manual Essay

Optical Training Manual Essay.

An Occupational Lens (or Enhanced Reader) is a reading lens that has a Degression zone to incorporate the Intermediate prescription (and sometimes, depending on prescription, a good DV portion)

Why dispense an Occupational Lens, instead of a Reading pair of glasses? With more and more people using Computers, Laptops and Smartphones, we demand more from the Intermediate zone than ever before. So by dispensing a pair of Reading glasses to a (Pre)Presbyope we are predominantly only taking care of one aspect of the cx’s working or home life day.

Therefore, with the introduction of the Occupational Lens, we can ensure the cx is able to see both the NV and INT zone without compromise. Who to Dispense an Occupational Lens to:

Any (Pre)Presbyope, therefore, anyone who has a Reading Add of +0.75 and above, for those with less than a +0.75 Add, there is an alternative lens that can be offered (more about that another time) – Anti Fatigue (0.60 Degression). Types of Occupational Lenses available at Specsavers:

1.498 Sola Access (0.75 and 1.25 Degression)
Very good entry level Occupational lens

1.498 Enhanced HD (0.75 and 1.75 Degression)
1.60 Enhanced HD (0.75 and 1.75 Degression)
More advanced Occupational Lens , better suited for those with higher Add powers

1.498 Hoya Tact (+1.00D to +3.00D Add available)

A pre-introduction to varifocals as this lens gives you more distance vision compared to the other 2 lenses – http://www.hoyavisioncare.com/asia/index.php?option=com_content&view=article&id=67&Itemid=84

All of the above lenses are available with Specsavers UltraClear Coating (UC), and can also be tinted up 8% LTF (very dark) Features:
Lens Name | Sola Access | Enhanced HD | Hoya Tact | Degression’s available | 0.75 & 1.25 | 0.75 & 1.75 | N/A | Additions available | N/A | N/A | 1.00 – 3.00 | UltraClear | Y | Y | Y |

Tintable (up to) | 8% LTF | 8% LTF | 8% LTF | Fitting Cross (above HCL) | HCL | HLC | 10mm | Minimum Fitting Height | 19mm | N/A | 18mm | Indexes available | 1.498 | 1.498 & 1.60 | 1.498 |

Benefits:

Excellent INT and NV Zone compared to a regular VF
Good, but limited DV Zone (great for home/office based environment) No longer a need to carry around several pairs
How do you dispense an Occupational Lens?
Both the Sola Access and Hoya Tact are dispensed like a regular Varifocal (taking mono PD’s and Heights). The Enhanced HD can be dispensed like a regular SV lens fitting the lenses on HCL, however, to get the best out of the lens, it is advisable to put vertical heights in. This way you are making sure the cx gets the best out of the lens (high RX’s +- 3.00 and above should have vertical heights automatically). Advantage to Specsavers and you:

By dispensing Occupational lenses over Single Vision Reading lenses, we are increasing our ATV (Average Transaction Value), therefore increasing our weekly sales. This also means BONUS is more likely.

Example:

Reading Lenses @ ?69.00 (1.498 with UC)
X 7 days x 4 weeks = ?1,932.00 Revenue generated on one pair of reading lenses per day for a month

Occupational Lenses @ ?109 (1.498 with UC)
X 7 days x 4 weeks = ?3,052.00 Revenue generated on one pair of reading lenses per day for a month

Therefore, an increase of ?1,120.00 in Revenue generated for the month. This could mean the difference between Bonus and NO Bonus

Speaking of Bonus, the person that dispenses the most Occupational Lenses will be rewarded by the Directors. Please keep a note of each Occupational Dispense you do and give to Christian at the end of each week.

Optical Training Manual Essay

Refractive Indices of Water And Turpentine Oil Essay

Refractive Indices of Water And Turpentine Oil Essay.

To find Refractive Indices of Water And Turpentine Oil using a plane mirror, a equiconvex lens (made from a glass of known refractive index) and an adjustable object needle

APPARATUS:
A convex lens, an optical needle, a plane mirror, a clamp stand, a spherometer, a plumb line, metre scale, water and turpentine

oil Theroy :
Let’s add small amount of water on a flat, plane surface and place a convex lens over it. This forms a plano-concave lens of water between the lower surface of convex lens and plane mirror.

Let f 1 and f 2 are the focal lengths of water lens and convex lens respectively, then focal length of the combination is:

The focal length of the plano-concave lens is, …(i)
From Lens Maker’s formula,
=( R 1 = R and R 2 = for water lens.

The refractive index of water is , …(ii)

(where ‘R’ is the radius of curvature of the concave surfaces of the plano-concave lens). The Radius of curvature of the lens, is …(iii)

PROCEDURE
• For finding the focal length of convex lens:
• Measure the rough focal length of the convex lens.

• Place the plane mirror with the convex lens placed on it above the horizontal base of a clamp stand horizontally as its tip lies vertically above the optical centre of the lens. Adjust the needle at a height a little more than the rough focal length of the convex lens.
• Try to remove the parallax between the tip of the object needle and its image tip.
• Note the distance of the tip of the needle from the centre of the upper surface of the lens. Let it be x 1. (Use plumb line).
• Remove the convex lens and measure the distance of the tip of the needle from the plane mirror. Let it be x 2 . (Use plumb line). 2 (vi) Repeat and record all the observations.
• For finding the focal length of the plano-concave lens: Pour few drops of water over the plane mirror and place the convex lens over it. Repeat steps (ii) to (iv) as done above.Repeat the procedure with turpentine oil also.
• For finding ‘l’:

Determine the pitch and least count of scale of the spherometer. Place the spherometer on the dried surface of the convex lens. Turn the screw downwards very gently till the tip of the screw just touches the lens. Read and record the reading. Keep the spherometer’s legs on the base of a paper and adjusting the central screw, find the pricks A, B and C of the three legs of the spherometer. Join the centres of the three pricks and measure the lengths with the half-metre scale. Note the values of AB, BC and AC

Conclusion

Pitch of the spherometer= 1 cm
Least count of the spherometer = 0.01 cm
Distance between the legs:
• AB = 3 cm
• BC = 3 cm
CA = 3 cm
S.No
Initial reading of the C.S. on the convex lens
(a)
No. of complete rotations

(n)
Final reading of the c.s on the glass slab
Additional C.S div. moved
h=n x pitch + m x L.C
Mean “h”
1
62
0
6.5
55.5
0.555
0.5775
2
64
0
4
60
0.6

Aim is to find the refractive index of a) water, b) coconut oil using a plane mirror, and an equiconvex lens made of glass and an adjustable object needle. The theory behind liquid lens is based on the properties of one or more liquids to create magnifications within a small amount of space.The focus of a liquid lens is controlled by the surface of the liquid .Water normally forms a bubble shape when adhered to materials such as glass.This desirable property makes water a very suitable candidate for the production of liquid lens.Essentially the liquid must be transparent so as to study its effects. To generate a liquid lens , a liquid is sandwiched between two pieces of a clear plastic or a glass. Oil (necessarily transparent) can also be chosen to be used as a fluid in a liquid lens system. The surface profiles of the liquid determines the focal length of liquid lens system and how the liquid lens focusses light rays.

Theory:

In optics, refractive index or index of refraction ‘n’ of a substance (optical medium) is a dimensionless number that describes how light or any radiation propagates through that medium.It is defined as n = c/v

where’ c’ is the speed of light in vaccum and ‘v’ is the speed of light in a substance. Eg : ‘n’ of water is 1.33, which means, light travels 1.33 times as fast in vaccum as it does in water. The historically first occurance of refractive index was in Snell’s law of refraction. ie are the angles of incidence of the ray crossing the interface between 2 medias with refractive indeces n_1 and n_2. In this project, we shall make use of the property of liquid lens to find the refractive index of water and coconut oil.

Requirements

A convex lens, plane mirror, water, coconut oil, an optical needle, an iron stand with base and clamp arrangement, a meter scale etc…. Procedure :
• Finding the focal length of convex lens:-
• Place the plane mirror with the convex lens placed on it above the horizontal base of a clamp stand horizontally as its tip lies vertically above the optic centre of the lens. Adjust the needle at a height a little more than the rough focal length of the convex lens.
• Bring the tip of the needle, at the vertical principal axis of the lens, so that the tip of the needle appears touching the tip of its image.
• Move the needle up and down to remove the parallax between tips of needle and its image.
• Measure the distance between tip of the needle and upper surface of the lens by using a meter scale. Let it be (x1 ).
• Again measure the distance between tip and upper surface of the plane mirror. Let it be x2
• Finding the focal length of the combination:
• Take a few drops of the given transparent liquid and place it on the surface of plane mirror. The convex lens is placed over it as before. (A plano concave lens is formed between plane mirror and convex lens).
• Repeat the steps (ii) to (v)
• Record the observations.
• To find the radius of curvature of the liquid lens. (R of convex lens surface in contact). The convex lens is turned towards a source such that, the required surface is away from the source the distance is to adjusted that the image is, formed on the side of the source. The distance ‘d’ between the source and the lens is measured.

The radius of curvature ‘R’ of the lens is given by

Finally the refractive index of liquid lens is given by.
n = 1+ R/f2
Result :
The observations of the experiment is tabulated as follows

Precautions
• The parallax must be removed tip to tip properly.
• The lens and plane mirror should be cleaned thouroughly.
• The liquid taken should be essentially transparent.
Only few drops of liquid should be taken so that the liquid lens layer is not thick

Sources of error :
• Liquid may not be quite transparent
• The parallax any not be fully removed
• The needle may not be properly horizontal
The distance x1 and x2 may not be essentially clean

The experiment described in this project is an effective and simple method of measuring the refractive index of any liquid (transparent) using a convex lens and plane mirror. If we keep the mirror behind a lens and put an object at the focus point of the lens above it, the image of the object will form at the same focus point where the object is. If it is an extended object, its image will be inverted and the size of image is same as that of the object. This property has enabled the efficient use of liquid lens to find the refractive index of a fluid by this method. If a liquid is sandwiched between the lens and the mirror, the focal length of liquid lens can be calculated knowing the focal length of the combination and that of the convex lens, from which the refractive index of the fluid can easily be estimated.

Refractive Indices of Water And Turpentine Oil Essay

The Microscope: Science’s Greatest Invention Essay

The Microscope: Science’s Greatest Invention Essay.

The microscope has been one of the greatest inventions in the history of science and has had the most impact on the course of science. Ever since the first microscope was invented in 1590, they have improved our knowledge in basic biology and biomedical research, as well as many other things, all of which are important. The smallest object a human can see with the naked eye is 0.2 mm, for example, algae cells. The light microscope, however, allows us to see things almost 1000 times smaller that what the eye can see, like plant, animal, and bacteria cells, and the electron microscope allows us to see things almost 1,000,000 times smaller, like viruses and proteins.

The Italians paved the road to the invention of the microscope when they discovered how to grind lenses during the 1300’s, and as a result, created the first spectacles. The first microscope was developed in 1590 by two Dutch lens grinders and spectacle makers Hans Janssen, father, and Zacharias Janssen, son, when they put two grinded lenses inside a tube.

Later in the 1700’s, many discoveries were made to improve the microscope. One was that lenses combining two types of glass could reduce the chromatic effect the previous microscopes had. Then, in 1830, Joseph Jackson Lister came up with another way of improving microscopes.

He reduced the problem of spherical aberration by using several weak lenses together at different distances giving good magnification without blurs. All of theses microscopes were light microscopes, however, so they were not powerful enough for the growing demand of magnification. This was soon solved when, in 1903, the ultramicroscope was developed by Richard Zsigmondy which could study objects under the wavelength of light, and in 1938, the electron microscope was developed by Ernst Ruska which greatly improved the resolution and magnification, and expanded the borders of exploration.

Microscopes look like very complex objects, but are actually not. Microscopes need to gather light from a tiny area of a thin, well-illuminated specimen that is close-by. Thus, the job of the light bulb. It is used to produce light that is all but blocked and concentrated to a tiny hole in the middle where the specimen is. Then the light shines through the specimen, and into the first lens, the objective lens, which gathers the light from the specimen, and passes it on to the second lens, the ocular lens or eyepiece, which magnifies it into your eye.

The coarse focus is used to make rough adjustments to make the picture less blurry and the fine focus is to fine-tune it. The nosepiece is used to change the objective lens which means you can change the magnification. Electron microscopes, on the other hand, are much more complicated. Basically, a stream of electrons is generated by an electron source, and is projected at the specimen. The stream is concentrated into a thin, focused, beam, and is focused at the specimen by a magnetic lens. Reactions and interactions occur inside the specimen, affecting the electron beam, which is then translated into a picture.

The invention of the microscope has definitely been a turning point in the history of man. With a microscope, we can now explain many phenomena we always thought were the creation of “freaks of nature” or God’s whims, like viruses and bacteria, and even how the body works. The first major discovery that used the microscope was made by Robert Hooke, who used his microscope to study various things, including corks. He was amazed to see that there were “holes” in the cork and decided to call them cells since they reminded him of the cells in monasteries monks lived in. Another major discovery that required the microscope was the discovery of single-celled organisms like protists and bacteria. These two discoveries sparked the accumulation of the monumental amount of knowledge of science we have today in biology, and even quantum physics and chemistry.

The Microscope: Science’s Greatest Invention Essay