The interferometer uses a precision-engineered lead screw with a diameter of 17 millimeters, a pitch of 1 millimeter, and a threaded length of 200 millimeters.
>To maintain high accuracy and even movement, both the lead screw and its matching nut are optically lapped, ensuring the pitch remains consistent across the entire travel range.
For accurate measurement and positioning, the instrument features three separate scales:
- Linear Scale: A scale that measures from 0 to 150 millimeters, marked in millimeters, is mounted on the left side of the interferometer bed for rough measurements.
- Graduated Disc: This disc is inside the interferometer head and can be seen through a glass window.
It is divided into 100 equal parts, with each part representing 0.01 mm, allowing for detailed measurement adjustments.
- Slow Motion Drum: Positioned on the right side of the instrument, the drum is marked from 0 to 100 divisions, with each division corresponding to 0.00001 mm, enabling highly accurate movement and measurement.
Together, these scales allow the interferometer to achieve a least count of 0.0001 mm (10⁻⁴ mm), which is essential for precise optical experiments and research
Optical Components
The interferometer uses two mirrors that are partially coated and have high-quality metallic coatings for improved reflectivity and long-lasting performance.
>The optical setup is designed to create clear and well-defined interference fringes, with the D₁ and D₂ spectral lines of sodium being clearly visible even without the aid of a magnifying device.
Each mirror is made from high-grade optical glass and has a step-like design.
>The coated surface of each mirror has a diameter of 23 mm, while the back surface measures 27 mm in diameter. The thickness of the mirrors is 12 mm, contributing to their structural strength and stability.
Key optical properties of the mirrors include:
- Surface accuracy of the coated face: Better than λ/10
- Reflectivity: Approximately 80%
- Coating material: Aluminium (Al) with a protective Silicon Dioxide (SiO₂) coating to improve durability and resistance to environmental factors.
Telescope Specifications
The observing telescope is equipped with a high-quality achromatic doublet objective lens that has a diameter of 25 mm and a focal length of 50 mm.
>The optical system provides a magnification of 10×, allowing for clear viewing of interference patterns and fine optical details with excellent image quality and minimal chromatic aberration.
This precise optical setup makes the interferometer ideal for use in educational labs, research facilities, and advanced studies related to interference, wavelength measurement, and optical measurement techniques.
