1. Introduction

First and foremost, “light” constitutes a portion of the electromagnetic spectrum. This “light” is broadly categorised into three types: “infrared”, “visible light”, and “ultraviolet”.
This article will explain “visible light”.

2. What is the wavelength range of visible light in nanometres?

Visible light refers to the range of light perceivable by the human eye, with a wavelength range of approximately 380nm to 750nm. This range lies between ultraviolet and infrared light and constitutes the colours of the rainbow observed in daily life. Visible light forms colours by passing through portions of white light and serves to convey various information to humans.
Furthermore, visible light influences numerous technologies relevant to our daily lives. Examples include communication technologies utilising light and image processing technologies employing light. Furthermore, health improvement technologies utilising the properties of visible light have been developed. Visible light is also crucial as a means for transmitting energy and information, and its applications continue to expand alongside technological advancements. Light wavelengths are deeply connected to our senses and are known to exert psychological effects through various hues and brightness levels. For instance, blue light is considered to enhance concentration.

3. The relationship between visible light wavelength range and color

The wavelength range of visible light is perceived visually as different colors. Violet lies at the short-wavelength end, transitioning through blue, green, yellow, orange, and red as the wavelength increases. The wavelength for each color is as follows:

– Violet: 380nm – 450nm
– Blue: 450nm – 495nm
– Green: 495nm – 570nm
– Yellow: 570nm – 590nm
– Orange: 590nm – 620nm
– Red: 620nm – 750nm

The combination of these wavelengths enables us to perceive a rich spectrum of colors. Visible light also serves as a means to convey emotions through color and to understand the shape and texture of objects. For instance, red often signifies warnings or danger, while green frequently represents nature or peace. Although color perception can vary across cultures and regions, the fundamental characteristics of wavelengths are universal. Furthermore, color is known to influence our psychology. Psychologically, color perception is considered to significantly affect emotions and mood; for example, warm colours are thought to have an energising effect.

4. Electromagnetic waves and other wavelengths of light

4-1. What is ultraviolet light?

Ultraviolet radiation is a type of light (electromagnetic wave) invisible to the human eye, occupying a wavelength range shorter than visible light but longer than X-rays. It is sometimes abbreviated as “UV”, derived from the initial letters of “Ultraviolet”.As part of the light (electromagnetic waves) contained within sunlight, its energy is higher than that of visible light, thereby exerting various effects on living organisms and materials.

4-2. What is infrared light?

Infrared radiation is another type of light (electromagnetic wave) invisible to the human eye, occupying a wavelength range longer than that of visible red light but shorter than radio waves. It is termed “Infrared” and is also abbreviated as “IR”.A major characteristic of infrared radiation is its thermal effect. When an object possesses heat, it emits infrared radiation corresponding to its temperature. For this reason, it is also called a “heat ray”. The warmth we feel when bathed in sunlight or when standing in front of a stove is due to this infrared radiation. All matter above absolute zero (approximately -273°C), including our own bodies, emits infrared radiation.

5. The role of optical filters and visible light

Optical filters control light characteristics by selectively transmitting or reflecting specific wavelengths. This enables the removal of unwanted light and the enhancement of particular hues or contrast. Filters are produced by applying coatings to materials such as glass or plastic that absorb or reflect specific wavelengths of light.
Optical applications are also the most numerous compared to other wavelength bands, encompassing a diverse range of products from imaging equipment such as smartphones and projectors, to analytical instruments like microscopes and measuring devices, and lighting equipment represented in recent years by LEDs. Optical filters are used in many of these, with various customisations made depending on the application.

Related product pages: Band pass filter, Long pass filter, Short pass filter, AR coating

5-1. Basic principles of optical filters

The design of optical filters demands precision engineering, with performance significantly influenced by the materials used and coating methods employed. Modern optical filter technology enables unprecedented control over light, greatly contributing to scientific and industrial advancement. By finely controlling light wavelengths, optical filters facilitate higher-precision analysis and observation, expanding possibilities in research and development.

5-2. Types and characteristics of visible light filters

There are several types of visible light filters. For instance, colour filters are used to emphasise specific colours, while bandpass filters only transmit a specific wavelength range. Additionally, cutoff filters block wavelengths below a certain threshold, transmitting only those above it.
Filter efficiency and durability are also crucial factors, demanding appropriate materials and design. Depending on the filter type, multiple filters may be combined to enhance effectiveness under specific environmental conditions. Thus, visible light filters continue to evolve to meet diverse applications and requirements, with applications anticipated across various fields. To maximise filter effectiveness, employing the latest technology and knowledge to achieve optimal filter design is essential.

6. Summary

This time, we explained visible light from its basic definition through color relationships to filters designed for visible light.
Visible light is both a vital source of information for how we perceive the world and an indispensable element for the advancement of science and technology. We hope this article helps deepen your understanding of the wavelengths of visible light.