Physics Lab Equipment

LETI-30 Thermal Expansion Experiment - Optical Interference

LETI-30 Thermal Expansion Experiment - Optical Interference


  • Compact structure

  • Various types of specimens

  • Low power consumption

  • High accuracy


This apparatus employs a Michelson interferometer and an oven, together with a temperature sensor for precise temperature control of the specimen under test. Both ends of the specimen in the oven are isolated from the rest of the specimen arm with quartz so that the thermal expansion of the specimen arm is dominated by the specimen. Displacement of the specimen due to thermal expansion is measured in terms of the number of interference fringes passed by visual counting. Therefore, the thermal expansion of the material under test can be calculated accurately on the order of a half wavelength of the He-Ne laser.

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


He-Ne Laser1.0 mW@632.8 nm
SpecimensCopper, aluminum, and steel
Specimen Length150 mm
Heating Range18 °C ~ 60 °C, with temperature-control function
Measurement Accuracy of Temperature Change0.1 °C
Display Value Error± 1%
Power Consumption50 W

Error of Linear Expansion Coefficient

< 3%

Part List

Thermal Expansion Experiment Unit1
He-Ne Laser (LLL-2-A)1
Plane Mirror2
Power Cable1
Lift Tool1
Manual Counter1
Aluminum Alloy Specimen1
Copper Alloy Specimen1
Steel Specimen1

LETI-30 Thermal Expansion-1.jpg

1. Digital temperature controller

2. Viewing screen

3. Beam splitter

4. He-Ne laser

5. Beam expander

6. Fixed mirror

7. Folding mirror

8. Movable mirror

9. Quartz tube

10. Oven

11. Specimen

12. Temperature sensor

13. Quartz base

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