# Calculating distance between lux meter and light source

• san-yas
In summary, the conversation discusses the use of the inverse square law to calculate the distance between a light source and a lux meter. It is noted that this law may not work for sources with significant area or for laser sources due to their distributed nature. It is suggested to conduct an experiment to determine the distance at which the inverse square law becomes effective.

#### san-yas

I am currently performing some experiments to calculate the distance between a light source and a lux meter where the light source points directly towards the lux meter.
Is it possible to calculate the exact distance between the light source and the lux meter given that we have a lux value (through the lux meter) and the luminosity flux (through the information given by the light source manufacturer)? or is the inverse square law (lux=lm/d^2) subjected to particular conditions?

Welcome to PF.

It seems like the inverse square law should work for this. What have you seen in your experimental data so far?

san-yas said:
a light source
If the source has a significant area then ISL will stop working close up. Also, if the source is a laser, you will have a problem because the effective position of the source can be may metres behind the front (multiple mirror images, as with an infinity mirror) and the r in 1/r2 would need to be corrected for. ISL is fine for stars and planets but the Moon and Sun are very much distributed sources.

I would be inclined to do the experiment first and find what distance the ISL begins to work for.

berkeman

## What is a lux meter and how does it work?

A lux meter is a device used to measure the intensity of light in a given area. It works by measuring the amount of light that falls on a surface in a specific area and converting it into a unit of measurement called lux.

## Why is it important to calculate the distance between a lux meter and a light source?

The distance between a lux meter and a light source is important because it affects the accuracy of the lux meter readings. The closer the lux meter is to the light source, the higher the readings will be. By calculating the distance, you can ensure that the lux meter is at the correct distance for accurate measurements.

## What is the formula for calculating distance between a lux meter and a light source?

The formula for calculating distance between a lux meter and a light source is: D = √(E / A), where D is the distance in meters, E is the illuminance in lux, and A is the area in square meters.

## Can the distance between a lux meter and a light source affect the type of light source being measured?

Yes, the distance between a lux meter and a light source can affect the type of light source being measured. Different types of light sources have different light intensity patterns, and the distance can affect how much light is measured by the lux meter. Therefore, it is important to know the type of light source being measured and adjust the distance accordingly.

## Are there any other factors that can affect the accuracy of distance calculations between a lux meter and a light source?

Yes, there are other factors that can affect the accuracy of distance calculations between a lux meter and a light source. These include the angle at which the lux meter is held, the reflective properties of the surface being measured, and any obstructions between the lux meter and the light source. It is important to consider these factors and make adjustments as needed for accurate distance calculations.