Everything You Should Know About Wavemeter

Scientific instruments are used for studying both theoretical research and natural phenomena. Wavemeter is also known as a wavelength meter. It is a kind of interferometer. The wavemeter is generally used for the measurement of the wavelength of light. Light rays which are delivered in the form of laser beams are measured by a wavemeter. A wavemeter also acts as an important device in measuring the wavelength or the frequency of an electromagnetic signal or radio signal. It is generally used for measuring the frequency that does not require high accuracy. 

Meaning of Wavemeter

Wavemeter is a device which is used for measuring the frequency or wavelength of a light beam or the frequency of an electromagnetic signal or radio signal. 

There are mainly two arms in a wavemeter. One of the arms has a fixed length, while the length of the other arm of the wavemeter varies in length. The length variation is implemented with a corner cube reflector that slides on an air track with very little friction.

Types of Wavemeter 

A wavemeter can be of three different types:

1. Absorption wavemeter
2. Transmission wavemeter
3. Cavity wavemeter

Absorption Wavemeter

• An absorption wavemeter is the most common type of wavemeter used for measuring the frequency of radio waves. It is also an older way of measuring the frequency. It has been used since the early 20th century, after the invention of the radio, till the 1970s. 
• The absorption wavemeter is also known as the reaction wavemeter. 
• After the 1970s, various other ways of measuring the frequency were invented that measured with more accuracy as compared to the absorption wavemeter. 
• Instead of an absorption wavemeter, a dip meter is used for the detection of mobile phones. 
• The absorption wavemeter is generally used for measuring the frequency that does not require very high accuracy.
• Absorption wavemeters absorb energy from the radio frequency and are loosely coupled with it.
• The resonant circuit present in the absorption wavemeter absorbs energy when it is adjusted to the resonance frequency. After that, it is easy to measure the frequency on the basis of the reading shown on the dial.

Transmission Wavemeter

• A transmission wavemeter is another type of wavemeter that is coupled with a probe to the main line.
• It contains an input and output port. Both the ports are fixed into the same path. At the output, it comprises a coupling loop.
• When the cavity of the transmission wavemeter is resonant, that is, when the frequency of an applied periodic force is equal to or close to the natural frequency of the wavemeter, the maximum energy reaches the load of the wavemeter. 
• The natural frequency of oscillation can be read from the wavemeter.

Cavity Wavemeter

• In a microwave, circuit cavities are used as circuit elements and as measuring instruments.
• Cavity wavemeter is generally used as frequency meters in microwave circuits or circuit elements. 
• In cavity wavemeters, tunable cavities are used. The main waveguide lies perpendicular to the axis of the cavity. A small circular hole or iris is used for coupling from the cavity to the wave guide.
• Factors on which the accuracy of the cavity wavemeter depends are the skills of the operator, temperature stability, and initial calibration.
• Higher initial calibration leads to higher accuracy of the cavity wavemeter.

Uses of Wavemeter

• The wavemeter is generally used for the measurement of the wavelength of light.
• A wavemeter also acts as an important device in measuring the wavelength or the frequency of an electromagnetic signal or radio signal.
• It is generally used for measuring the frequency that does not require high accuracy. 

Aspects for Selecting a Wavemeter

A wavemeter can be of different types and can differ in many aspects:

• Most of the wavemeters consist of a reference laser which lies on the internal side. Some of the wavemeters are using an external source.
• In some wavemeters, the input light is provided by a fibre-optic connection, while in some, it is provided as a free-space laser beam.
• Generally, the wavemeters work in a limited wavelength range. Only a few can work for extreme wavelength regions.
• Usually, the wavemeters only show the wavelength, but in a few wavemeters, the line width is also seen.

Conclusion 

Wavemeter is also known as a wavelength meter. It is a kind of interferometer. It comprises two arms and is used for measuring the frequency or wavelength of a light beam or the frequency of an electromagnetic signal or radio signal. It can be of three types: Absorption wavemeter, transmission wavemeter and cavity wavemeter. An absorption wavemeter is the most common type of wave matter used for measuring the frequency of radio waves. It is also an older way to measure the frequency. Cavity wavemeter is generally used as frequency meters in microwave circuits or circuit elements. In cavity wavemeters, tunable cavities are used. A transmission wavemeter is another type of wavemeter that is coupled with a probe to the main line.