# Increasing the divergence of a laser.

• will171

#### will171

I am slightly unsure about how the divergence can be increased by the use of either bi-concave or plano-concave lenses. I understand the general theory behind it but am having trouble putting numbers to it. e.g. if you have a laser beam with a diameter of 2mm and a divergence of 2mrad what focal length lens would be needed to increase its divergence to 5mrad/10mrad/etc? Any help would be greatly appreciated especially if it explains the calculations needed to work these things out.

A gaussian beam (most laser beams) have a really nice property- the product of divergence and beam waist is a constant. So, if the initial beam has a waist of 2 mm and divergence of 2 mrad and you want a divergence of 10 mrad, you only need focus the beam to a waist of 0.4 mm.

## 1. What is divergence in a laser?

Divergence in a laser refers to the spreading out of the laser beam as it travels away from its source. This is caused by imperfections in the laser beam's shape and can result in a decrease in the laser's intensity and accuracy over long distances.

## 2. Why would someone want to increase the divergence of a laser?

Increasing the divergence of a laser can be useful in certain applications such as laser cutting or drilling, where a wide beam is needed to cover a larger area. It can also be used to create a larger spot size, which can be beneficial in medical procedures or laser welding.

## 3. How can the divergence of a laser be increased?

The divergence of a laser can be increased by using a larger aperture in the laser's optical system, adjusting the beam diameter, or using an external lens to expand the beam. These methods can help to reduce the beam's intensity and spread it out over a larger area.

## 4. What are the potential drawbacks of increasing the divergence of a laser?

While increasing the divergence of a laser can be beneficial for certain applications, it can also lead to a decrease in the laser's intensity and accuracy. This can result in a loss of precision and efficiency, which may not be desired in some applications.

## 5. Are there any techniques to decrease the divergence of a laser?

Yes, there are techniques to decrease the divergence of a laser. These include using a smaller aperture, reducing the beam diameter, and using an external lens to focus the beam. These methods can help to increase the laser's intensity and improve its accuracy over longer distances.