Optical Instruments: Definition, Functions, Types and Parts

Optical Instruments: Definition, Functions, Types and Parts - What is an optical device and what are its types? On this occasion About the knowledge.co.id will discuss it and of course about other things that also cover it. Let's look at the discussion together in the article below to better understand it.

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Optical Instruments: Definition, Functions, Types and Parts

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Optical Instruments are a means of human vision, both natural and man-made. The natural optical instrument is an eye and the artificial optical instrument is an aid for human vision to be able to observe objects that cannot be seen in detail by the eye.

Optical devices are tools in which one or more components use optical objects, such as mirrors, lenses or prisms. Optical devices utilize the principle of reflection and/or refraction of light. There are several optical devices including cameras, loops, microscopes, telescopes, projectors, and episcopes.

Optical instruments are divided into 2 models, namely a natural optical instrument and an artificial optical instrument. The natural optical instrument is an eye. Meanwhile, artificial optical devices are optical instruments other than the eye, namely in the form of microscopes, periscopes, binoculars, and others.

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Types and Functions of Optical Instruments

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  Eye

The eye is one of the most sophisticated human optical organs. These eyes function as the sense of sight, to be able to see anything.

The parts of the eye are:

Cornea: an outer part of the eyeball. Cornea is a thin layer of transparent and will be able to see light.

Aqueous Humor: a liquid found behind the cornea. Aqueous Humor functions to refract light that enters the eye.

Eye lens: a lens made of a clear, fibrous, elastic material. working properly can regulate the refraction that can be caused by an aqueous humor fluid in front of the lens. This eye lens functions as a convex lens, namely as an image forming that is real, inverted and can be reduced.

iris: a membrane in front of the eye lens that can form a circular slit. The iris functions to be able to regulate the amount of light that is allowed to enter through the pupil. The iris also functions to be able to give a color to the eye.

pupils: a round slit that the iris creates. This pupil functions to be able to regulate the amount of light that enters the eyeball. If the light entering the eye is very strong, the pupil will narrow. So that less light will enter the eyeball. If the light entering the eye is dim, the pupil will widen so that more light enters.

Retina or Jatropha: to be able to function as a shadow capture screen.

Yellow Spot: flakes in the retina that are very sensitive to a light. In order for the image to be clear, the image must also form on the retina perfectly in the yellow spot.

Optic nerve: a nerve that can connect the yellow spot with the brain so that some shadow signals from the yellow spot reach the brain. Then this brain will be able to translate it.

Accommodation Muscles: is a muscle attached to the lens of the eye that functions to be able to adjust the thickness and thickness of the eye lens.

Vitreous Humour: namely a liquid contained in the eyeball, serves to be able to transmit light from the lens of the eye to the retina.

Yellow Spot: namely a part of the retina that is used as a place in the formation of a clear image.

Blind Spot: is one part of the retina where if the image falls on this part, this image will appear unclear or blurred.

Eye Nerve: namely a nerve that functions to be able to continue image stimulation from the retina to the brain.

Sclera: to be able to protect the eyeball against external interference that is mechanical (ex. impact) and serves to maintain the shape of the eyeball.

Choroid: maintain a retina and in order to prevent the occurrence of light reflection in the internal space of the eye by absorbing light that is not needed.

Ciliary Muscle: to be able to adjust the curvature of the eye lens. Adjustment of this curvature can be needed so that the image of an object falls exactly on the retina.

In the retina, images are formed in an inverted, real, and diminished form. If the lens fails to do its job of focusing light, what will happen is that the image will become blurred.

There are three types of eye defects caused by the image not being formed exactly on the retina of the eye.

• • Nearsightedness (myopia)

People who have myopia cannot see objects that are far away from their eyes clearly, but can still see objects that are close to them normally. Myopia is also known as minus eye among the people.

Generally, the symptoms of myopia sufferers are not being able to see the writing on the blackboard or read billboards on the side of the road. Myopia can be overcome by using glasses or Lasik surgery.

• • Farsightedness (hypermetropia)

People who are hypermetropic have difficulty seeing objects that are up close.

Hypermetropia occurs when light entering the eye is focused behind the retinal surface of the eye. This can happen because the eyeball is too short, the shape of the lens or the cornea is not normal.

• • Presbyopia

Presbyopia is the loss of the eye's ability to see objects at close range. Presbyopia is visual impairment which is a sign of natural aging of the body.

The characteristics of presbyopia are often squinting when reading, often moving an object away so you can see it clearly, or feeling a headache after reading at close range.

The lens of the eye is surrounded by ciliary muscles which help in the task of focusing light that enters the eye. As you get older, the ciliary muscle will harden and become less elastic. This condition causes presbyopia.

Factors for a person suffering from presbyopia also vary, one of which is due to increasing age, taking antidepressant drugs, and having diabetes or heart disease.

In general, the way to treat presbyopia symptoms is to use special glasses prescribed by an ophthalmologist, wear contact lenses, refractive surgery, lens implants, and corneal inlays.

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  Camera

The camera is an optical device that can move or take pictures and save them in the form of files, films or print-outs.

A camera that uses a positive lens to form an image. The nature of the image that can be produced by the camera is real, inverted, and reduced.

• • Parts of the Camera, namely:

Convex lens,Setting the suoaya an incoming light can be well received by the film.

diaphragm,Sets the amount of light that will enter the camera.

film plate,As a place for shadows and can produce a negative image, namely an image that is not the same color as the original, translucent.

Prism,Bending a light so that it rotates around the inside of the camera so that the photographer can see the actual image that will be taken through a camera lens.

shutter,Allows the passage of light through the lens in a short time.

aperture,Set the size of a light diaphragm.

• • Example Problem: Camera

The focal length of a camera lens is 50 mm. The camera is set to focus the image of an object at infinity. How far must the camera lens be shifted to focus on an object 2.5 m away?

Answer :

When used to focus on objects that are far away at infinity, the image of the object will be right at the focal point of the lens.

In other words, s' = f = 50 mm. When the distance from the object to the lens is s = 2.5 m = 2500 mm, the image will be as follows

1/s + 1/s' = 1/f
1/2500 + 1/s' = 1/50
1/s' = 1/50 – 1/2,500
1/s' = 50 – 1/2,500
1/s' = 49/2,500
s' = 2,500/49
s' = 51.02 mm

Thus, the lens must be shifted as far as 51.02 mm – 50 mm = 1.02 mm.

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  Lup (Magnifying Glass)

Lup (magnifying glass) is an optical instrument that has a function to magnify the image of an object. The lens used in a magnifying glass is a convex lens. The image that can be produced by a magnifying glass is virtual, erect, and magnified.

The size of an image that can be produced by a magnifying glass can be calculated mathematically. How to calculate it can be distinguished according to the eye that will accommodate the maximum and also the eye that does not accommodate.

Not Accommodated :

M = Sn/f

Maximum Accommodation :

M = Sn/f + 1

Information:

M = magnification (times)
Sn = normal reading distance (25 cm)
f = focal length (m or cm)

Maximum Accommodating Eyes

The eye has maximum accommodation, which is one way of looking at objects at a nearby point (the ciliary muscles work maximum to be able to suppress the lens so that it is as convex as possible).

When using a lup with maximum accomodation of the eye, you need to pay attention to the following:

• • • The image to be formed by the loop must be at the point near the eye or the Proximum Punctum (PP).
    • The observable object must be placed between the focal point and the lens.
    • Weaknesses: the eyes will get tired quickly.
    • Advantages: magnification will increase (maximum).
    • Image properties: virtual, erect and magnified.

Maximum Accommodating Eyes

The eye has maximum accommodation, which is a way of looking at objects at a nearby point (the ciliary muscles work maximally to be able to suppress the lens so that it is as convex as possible).
When using a lup with maximum accomodation of the eye, it is necessary to pay attention to the following:

• • • The image to be formed by the loop must be at the point near the eye or the Proximum Punctum (PP).
    • The object to be observed must be placed between the focus point and the lens.
    • Weaknesses: the eyes will get tired quickly.
    • Advantage: the magnification will also increase (maximum).
    • Image properties: virtual, erect and magnified.

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  Microscope

A microscope is an optical instrument that has the function of being able to see small objects so that they appear larger and clearer.

This microscope consists of two convex lenses. The first convex lens is a lens that is close to the object being observed (object), which is also commonly called the objective lens.

The second convex lens is a lens that is close to the observer's eye, which is also commonly called the ocular lens. The image created by the microscope is virtual, inverted and magnified.

• Microscope Parts namely:

Lens Turner,On the player plate there is an objective lens. This plate can be rotated so that an objective lens is in the proper position.

objective lens,The objective lens is used to magnify the image of an object or preparation.

Clamp,Tweezers are used to be able to clamp glass objects or preparations so that they do not shift.

condenser,The condenser is used to collect light from the mirror to the preparation.

diaphragm,The diaphragm is used as a regulator of the amount of light leading to the condenser.

Mirror,Mirrors are used to reflect light from the light source to the condenser.

Ocular Lens,The eyepiece lens is used to magnify the image from the objective lens.

Microscope Body,The microscope body has a tube shape that can be raised or lowered.

macrometer,The macrometer is used to quickly raise or lower the microscope body.

Micrometer,The micrometer is used to slowly raise or lower the body of the microscope.

Microscope Arm,This microscope arm has a function as a place to hold the microscope.

object table,The object table is used as a place to put supplies. The part of the microscope table that is made is perforated for easy passage.

Condenser Player,The condenser player is used to be able to raise or lower the condenser so that optimal light can be obtained.

Microscope Feet,Microscope legs are used to maintain the balance of the microscope and so that the microscope can stand.

The magnification that a microscope can produce is a product of the magnification of the objective lens and the magnification of the ocular lens. Mathematically the equation is as follows:

M = M ob + M ok

Information:

M = microscope magnification (times)
Mob = objective lens magnification (times)
Mok = magnification of the ocular lens (times)

The length of the microscope is the result of adding the image distance of the objective lens to the image distance of the ocular lens. Mathematically the equation is as follows:

d = S'ob + S ok

Information:

d = length of microscope (m or cm)
sob' = image distance of the objective lens (m or cm)
sok = ocular lens object distance (m or cm)

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  Binoculars or Telescope

Binoculars are an optical instrument used to be able to observe objects that are far away so that they appear closer and clearer.

Binoculars are also often referred to as telescopes. This telescope was first discovered by Galileo Galilei. There are two kinds of binoculars, namely binoculars and binoculars earth stars.

Star binoculars can be used to observe celestial bodies, while earth binoculars are used to be able to observe objects on earth that are far from the observer.

• • Telescope

That is a binoculars used to be able to see or circle objects in the sky. For example, the stars, sky, and planets.

These binoculars can also be called astronomical binoculars. This star binoculars can consist of two types, namely when viewed from the course of the light, which is as follows:

Refractive binoculars are binoculars that consist of two convex lenses, namely an ocular lens and an objective. The way it works is when light enters the binoculars and is refracted by the lens.
Reflecting binoculars are binoculars that because of the way light can reflect inside the binoculars. The incident light may be collected in a large curved mirror and then reflected into the observer's eye by one or more much smaller mirrors.

The magnification of the telescope is:

M = fob: fok

The length of the binoculars is:

d = fob + foc

Information :

d = the length of the binoculars in meters
f (Ob) = focal length of the objective lens in meters
f (Ok) = focal length of the eyepiece in meters
fp = focal length of the inverting lens in meters

• • Earth Binoculars (Field Binoculars)

That serves to be able to observe objects that are far away on the surface of the earth. Consists of 3 convex lenses, each of which will consist of an objective lens, an inverting lens, and an ocular lens.

An inverting lens is a lens that will invert the image formed from the objective lens, not to enlarge an image.

This eyepiece functions as a loop that can be seen that the inverting lens is only to be able to reverse the image means that an image is formed by the objective lens which is located at the center of curvature of the inverting lens.

d = fOb + 4fp + fOk

Information :

d = the length of the binoculars in meters
f (Ob) = focal length of the objective lens in meters
f (Ok) = focal length of the eyepiece in meters
fp = focal length of the inverting lens in meters

• • Stage Binoculars

Namely a binoculars that can combine the positive lens and negative lens. Negative lenses can be used both as an averter and as an eyepiece. The nature of the image formed is virtual, upright, and diminished.

The working principle of stage binoculars is that parallel rays enter the objective lens which will form a real image right at the objective focus point.

This image will serve as a virtual object for the eyepiece. And the ocular lens will also form an image that can be seen by the eye.

d = f (Ob) – f (Ok)

Information :

d = the length of the binoculars in meters
f (Ob) = focal length of the objective lens in meters
f (Ok) = focal length of the eyepiece in meters

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  Periscope

That is a binoculars on a submarine that is used to be able to observe objects on the surface of the sea. The periscope consists of 2 convex lenses and 2 isosceles prisms.

The mechanism of the passage of light on perisco is as follows:

• • Parallel rays from a distant object are directed towards the objective lens.
  • The PI prism can reflect light from the objective lens to the P2 prism
  • So that the P2 prism is reflected again and crosses in front of the eyepiece right at the focal point of the eyepiece.

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  Slide Projector

That is one of the tools used to be able to project a diapositive image so that a real image can be obtained and enlarged on the screen.

This slide projector has several important parts, namely a small lamp that can emit a strong beam through the center of the glass, slide or also a diapositive image, a concave mirror that can function as a light reflector, a convex lens to be able to form an image on screen.

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  Ophthalmoscope

This tool is used to be able to examine the retina of the eye. In an image will be able to describe the important parts of the ophthalmoscope. The incoming light beam from the light source S which is located at a lens L1 focus is refracted parallel to mirror C.

From mirror C this light can be reflected to the eye. Furthermore, the doctor will be able to observe the retina through a hole in the middle of the C mirror and the L2 lens which acts as a loop.

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