Physics Lab Equipment

LEOI-53 Serial Experiments of He-Ne Laser Resonator and Modes

LEOI-53 Serial Experiments of He-Ne Laser Resonator and Modes

Note: oscilloscope not included


  • Including Additional He-Ne Alignment Laser

  • High Resolution

  • Ideal for Demonstration

  • Precise Measurement


The He-Ne laser serial experimental system (LEOI-53) is designed with an adjustable He-Ne laser cavity. By changing the cavity length or the radius of curvature of the cavity output mirror, corresponding change in lasing mode can be observed. The use of a confocal spherical scanning interferometer further allows students to directly observe the frequency distribution pattern of both longitudinal and transverse modes of a He-Ne laser. The scanning interferometer is also used to measure the frequency spacing between laser modes. Other optical parameters such as the spot size and the beam divergence angle of a He-Ne laser, and the free spectral range and the finesse of a scanning Fabry-Perot interferometer can be also measured with this system.

The instruction manual contains comprehensive materials including experimental configurations, principles and step-by-step instructions. Please click Experiment Theory and Contents to find more information about this apparatus.


He-Ne Laser Cavity with Brewster Window
  Radii of Curvature of Cavity MirrorsR1=∞ or R1=1 m; R2=1 m
  Cavity Length270 mm
  Center Wavelength632.8 nm
  Output Power≤ 1.5 mW
Confocal Spherical Scanning Interferometer
  Cavity Length20.56 mm
  Radius of Curvature of Concave Mirror20.56 mm
  Reflectivity of Concave Mirror99%
  Free Spectral Range (FSR)3.75 GHz

Sawtooth Wave Generator

  Modulation Amplitude of Sinusoidal Wave0 ~ 250 V, continuously adjustable
  DC Offset Voltage Output0 ~ 250 V, continuously adjustable
  Output Frequency20 ~ 50 Hz
He-Ne Laser for Beam Alignment
  Center Wavelength632.8 nm
  Output Power≤ 1 mW
Optical Rail1 m; aluminium

Optical Power Meter

2 µW ~ 200 mW, 6 scales

Part List

Optical Rail (LEPO-54)1

He-Ne Laser for Beam Alignment (LLL-2A)

Semi-External Cavity He-Ne Laser1
He-Ne Laser Power Supply1
Output Mirror1
Four-Axis Adjustable Holder (SZ-24)2
Two-Axis Adjustable Holder (SZ-06)2
Alignment Aperture1
High Speed Photo-Receiver1
Confocal Scanning Interferometer1
High-Voltage Sawtooth Wave Generator1
Optical Power Meter (LLM-2)1
Adjustable Slit (SZ-27)1
2-D Adjustable Holder (SZ-07)1
Plane Mirror1
Tape Measure1
User's Manual1

LEOI-53 He-Ne Laser-1.jpg

Gain curve and longitudinal modes

LEOI-53 He-Ne Laser-2.jpg

Modes shown on digital oscilloscope

LEOI-53 He-Ne Laser-3.jpg

Setup for measuring the spot size and beam divergence of He-Ne laser

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