Looking directly at the sun can lead to permanent eye injury due to damage of light-sensitive rod and cone cells within the retina. There are two ways to look at the Sun safely: by observing the sun directly through a suitable filter, or by projecting the Sun’s reflection onto a piece of paper via handmade pinhole camera/ telescope. The present correspondence shows the specification for the development of an optical instrument for the direct observation of sun. For this device, commonly available solar control glass plates can be used. The design of this filter is based on the fact that both visible and UV radiation comply with the law of Reflection and Refraction of light. As light rays appeared on the glass plate, most of the rays pass through the glass after refraction. A portion of the incident ray is mirrored and goes out to the next glass panel, where the same thing is going to happen. Through this way, multiple glass plates reflect the light ray before diffuse light is received. Owing to the fact that diffuse reflection is responsible for the ability to see most illuminated objects, we will be able to see the dull image of sun directly through this filter during the solar eclipse.

1. Dr Siddhant
Assistant Professor
Department of Botany
Durgesh Nandini Degree College, Ayodhya
INDIA
A NEW FILTER FOR SAFE VIEW OF
SOLAR ECLIPSE

2. WHAT IS SOLAR ECLIPSE
• Eclipses occur when one astronomical object moves in front of
another, or when an astronomical object moves into the shadow
of another object. In the sun-Earth-moon system, Eclipse takes
place when the new moon passes between the Earth and sun.

3. TYPES OF SOLAR ECLIPSE
There are mainly three different types of solar eclipses
1. Partial Solar Eclipse: occur when the Moon only partially obscures the Sun's disk and
casts only its penumbra on Earth.
2. Annular Solar Eclipse: take place when the Moon's disk is not big enough to cover the
entire disk of the Sun, and the Sun's outer edges remain visible to form a ring of fire in
the sky. An annular eclipse of the Sun takes place when the Moon is near apogee, and
the Moon's antumbra falls on Earth.
3. Total Solar Eclipse: happen when the Moon completely covers the Sun, and it can only
take place when the Moon is near perigee, the point of the Moon's orbit closest to Earth.
You can only see a total solar eclipse if you're in the path where the Moon casts its
darkest shadow, the umbra.

4. TYPES OF SOLAR ECLIPSE

5. Solar Retinopathy
• Solar retinopathy occurs when the harmful
radiation especially UV-B, UV-C as well as
Infrared rays from the sun reaches the eye
and is concentrated by the lens onto the
retina. Once absorbed into the retina, the
UV rays result in the formation of free
radicals. These free radicals start to oxidize
the surrounding tissues. They ultimately
destroy the rod and cones photoreceptors
in the retina. The oxidative damage is
referred to as solar or photic retinopathy.
• Ocular damage due to solar observation is
well known since centuries. Galileo the
famous scientist injured his eyes by solar
observation through the telescope.

6. SYMPTOMS OF SOLAR RATINOPATHY
• Unfortunately, the damage from solar retinopathy can occur without any feeling of
pain and the visual effects are not noticed for several hours after the damage has been
done. After few hours, the following symptoms appears:
A. For mild cases of Solar retinopathy:
 watery eyes
 discomfort looking at bright lights
 eye soreness
 Headache
B. The following symptoms might occur in more serious cases:
 blurred vision
 decreased colour vision
 difficulty discerning shapes
 distorted vision
 a blind spot or multiple blind spots in the center of your vision
 permanent eye damage

7. SAFE VIEW OF SOLAR
ECLIPSE
• There are two ways to
look at the Sun safely: by
observing the sun
directly through a
suitable filter, or by
projecting the Sun’s
reflection onto a piece of
paper via handmade
pinhole
camera/telescope/mirror
Solar filter the only way to direct
observation of sun

8. PINHOLE CAMERA/PROJECTOR
1. Stand with the sun behind you. 2. Point the pinhole
end of the box towards the sun. Move around until an
image of sun appeared inside the box through the
viewing opening, The longer the box, the greater will
be the sun’s image.
Build a pin hole camera /box
projector

9. OPTICAL PROJECTION BY
TELESCOPE
My setup for Solar Eclipse
Solar Eclipse at the
glance (June 21, 2020)
Project sun’s image
with a Telescope

10. OPTICAL PROJECTION BY MIRROR
The simplest and safest
method to produce a clear
image of sun. It is 'reflected
pinhole' which is just a small
mirror, as shown in the image,
blacked out with tape leaving a
small square of about 1.5 cm.
Point the mirror towards the
sun so that an image is
reflected on to the screen
about 15 feet away.

11. MATERIALS AND METHODS
This optical system uses the solar control
glass plates which is generally used for
windows and glazed facades in order to
modify indoor visual and thermal
comfort in buildings. These plates are
cut into the small rectangular pieces
with the dimensions of 5cm x3 cm. Each
glass plate is arranged on the card board
as shown in Figure.2 so that each may
reflect the incident rays at right angle.
The glass plates are also fixed on the
card board at right angle with the help of
clamps. Few cardboard plates are also
fixed on the base to minimize the
interference of rays. It should be in mind
when arranging the plates, the shiny
/mirrored face of plate should be
towards incident side.
Fig.1 Solar control glass showing different
faces
Fig.2 Arrangement of glass plates in cardboard box

12. RESULTS
 The design of the proposed filter is based on the fact that both visible and UV
radiation comply with the law of Reflection and Refraction of light.
As Sunlight incident on the first glass plate, most of the rays pass through the
glass after refraction.
A portion of the incident ray is mirrored at right angle and goes out to the
second glass panel where a large portion of light is refracted again.
After reflection from the second plate, the light rays incident on the next glass
plate where the same thing is going to happen.
Through this way, multiple glass plates refract and reflect the light ray before
diffuse light is received.
Owing to the fact that diffuse reflection is responsible for the ability to see most
illuminated objects, we will be able to see the dull image of sun directly through
this filter during the solar eclipse.

13. MECHANISM OF PROPOSED FILTER
(The number of glass plates shown is for presentation purposes only)

14. CONCLUSION
 This is new solar filter for direct
observation of sun/solar eclipse.
 The filter is safe for direct
observation of sun since much of
the visible, infrared and UV
radiation are filtered by
refraction,
 Further research on the proposed
solar filter is needed to improve
its efficiency.