Optical path diagram

Key features

If minute sample differences in refractive index exist in the parallel beam, light outgoing from the sample has a slightly divergent optical axis and focuses on a different spot. Eliminating the off-focus light with a knife edge makes it possible to project light with greater contrast.

	Points
Place the knife edge as close to the focal point as possible to improve contrast.

Key features of Sigma Koki products

A Schlieren device is an optical system that magnifies and projects minute angle displacements in the optical axis generated by the differences in refractive index that exist in the parallel beam, and demands precise adjustment of the optical axis and parallelism of the beam in which the sample is placed.

• Sigma Koki's concave mirror components facilitate adjustment of optical axis at a lower optical axis, thanks to sturdy support provided by a gimbal mirror holder, which minimizes deviations in optical axis during adjustment, and an XY-axis aluminum crossed roller stage joined to a magnetic base.
• Significantly reduces adjustment time when combined with a collimation checker component that visualizes the beam parallelism.
• Using an achromatic lens with minimal spherical aberration as the collimator lens minimizes scattering from the sample placed in the beam and increases contrast.

This is one example of an interferometer component available only from an all-round optical manufacturer with long-established comprehensive quality controls covering every process, starting with basic components, as well as extensive know-how in the assembly of optical devices.