QUANTIFYING THE EFFECT OF TUNGSTEN ILLUMINATION

by | Nov 2, 2022 | Physics, Experiments

Introduction

Through this experiment (quantifying the effect of tungsten illumination), we will see if we can create any model which can measure the amount of broader spectrum incandescent illumination required in addition to Low-Pressure Sodium to obtain normal colour perception.

The astronomer-friendly lightning, which is Low-Pressure Sodium (LPS) vapour, is very efficient and environmentally friendly but produces poor image synthesis of illuminated lights because of its narrowband emission.

Basic Building Concept

1. Sodium Vapour lamp is a kind of lamp in which sodium is used in an excited state to produce light of wavelength 589 nanometers.

2. It is of two types- a) low-pressure sodium vapour and b) high-pressure sodium vapour.

3. Low-Pressure Sodium Vapour lamp is an efficient lighting source. It produces monochromatic yellow light, which restricts its application but it is highly used for astronomical purposes.

4. High-Pressure Sodium vapour lamp produces a broader spectrum of light than Low-Pressure Sodium vapour, but it still produces poor colour rendering than other light sources.

Aim

To create a model for measuring the amount of broader spectrum incandescent illumination required in addition to Low-Pressure Sodium to obtain normal colour perception.

Requirements

1. Computer,

2. Digital camera,

3. Six Newtonian targets,

4. LPS vapour lamp,

5. Tungsten lamp,

6. A dimmer.

Theory

1. Low-Pressure Sodium Vapour lamp is an efficient lighting source. It produces monochromatic yellow light, which restricts its application but it is highly used for astronomical purposes.

2. Tungsten illumination is incandescent that uses pressurized halogen gas for illuminating light. It works like another lighting source.

The low-pressure sodium vapor

Procedure

Step 1: Create six Newtonian colour targets and illuminate them by 43000 lux from an eighteen-watt LPS lamp and by variable lux ranging from 0 to 3080 lux with a hundred-watt tungsten lamp.

Step 2: Regulate them with a dimmer.

Step 3: Click over 600 pictures of those targets and measure them photometrically.

Step 4: Now, you need to develop a program for converting RGB pixel data of each picture into CIE L*b*c values and for measuring delta E colour variance against a hundred per cent colour reference by using a C++ programming language.

Step 5: On the basis of the average of delta Es of the Newtonian spectrum, make a Color Rendering Value (CVR) for each sample ranging from 0 to 100.

Step 6: Now, find out the average value of CRV’s sample and make its graph to find out an equation that relates the tungsten percentage and CRV.

Observation

1. We have observed that the LPS lightning is greater by 26%.

2. Tungsten lightning synthesises images with near-normal colour perception.

3. We can obtain higher standards by illuminating a higher amount of tungsten lightening.

4. LPS combined with broader spectrum illumination like tungsten illumination can prove to be an alternative for outdoor lighting. This is environment friendly and also cost-effective.

Result

1. The CRV for 2.5% illumination was 2.3, for 15.0% was 3.4, for 26.0% was 13.7, for 35.9% was 30.1, for 42.7% was 41.2.

2. An equation that relates tungsten percentage W to colour perception indexed by Color Rendering Value is

CRV = 38arctan (0.07W – 3.2) + 49.5

Precaution

1. Make sure the program is working properly.

2. Pictures should be taken clearly.

3. Camera should be clean before clicking pictures.

Conclusion

In this experiment, we have examined the effect of illumination of tungsten on colour rendering of LPS vapour light with the help of a program that can analyse CCD pixel data and also derived a formula that relates colour rendering and tungsten percentage.

Viva Questions with Answers

Q.1 What was the aim of your experiment?

ANS. To create a model for measuring the amount of broader spectrum incandescent illumination required in addition to Low-Pressure Sodium to obtain normal colour perception.

Q.2 What do you understand about sodium vapour lamps?

ANS. A sodium Vapour lamp is a kind of lamp in which sodium is used in an excited state to produce light of wavelength 589 nanometers.

Q.3 How many types of sodium vapor lamps are there?

ANS. It is of two types- a) low-pressure sodium vapor b) high-pressure sodium vapour.

Q.4 What do you understand about low-pressure sodium vapor lamps?

ANS. A low-Pressure Sodium Vapour lamp is an efficient lighting source. It produces monochromatic yellow light, which restricts its application but is highly used for astronomical purposes.

Q.5 What do you understand about high-pressure sodium vapour lamps?

ANS. High-Pressure Sodium vapour lamps produce a broader spectrum of light than Low-Pressure Sodium vapour, but it still produces a poor colour rendering than other light sources.

Q.6 What mathematical equation have you derived from this experiment?

ANS. CRV = 38 arctan (0.07W – 3.2) + 49.5

Q.7 What is the use of this equation?

ANS. This equation relates tungsten percentage W to colour perception indexed by Colour Rendering Value.

Q.8 What do you understand about tungsten illumination?

ANS. Tungsten illumination is incandescent that uses pressurised halogen gas for illuminating light. It works like other lightning sources.

 

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