PS990 In Stock

The PS990 by ThorLabs is a highly versatile dove prism that can be used to rotate, invert, or retro reflect an image. The PS990 is designed with two angled faces that are typically used together to rotate an image, while the longest face can be used to retro reflect an image. Its rotation angle and the surface through which the light enters the prism determine whether the image will be rotated, inverted or retro reflected.

The PS990 is constructed with N-BK7 glass material, ensuring high transmission to the near-infrared (NIR) spectral range from the visible spectral range. The PS990 is uncoated for the 350 nm to 2.0 µm wavelength range and has 5 mm square cross sections. Its angled faces and longest face are optically polished surfaces, while all other surfaces are fine ground to permit easy handling.

The PS990 is often considered as a right-angle prism that does not have a triangular apex, which decreases its weight and stray reflections that are internal. Although the prism can be used with converging light, it causes astigmatism. For best results, it is advised to use this prism with collimated light instead. Moreover, the PS990 affects the polarization state of light transmitted through it. Hence, care should be taken when clamping these prisms for applications sensitive to the polarization of the transmitted light as stress-induced birefringence can further alter the polarization of light incident on the prism.

The PS990 can be mounted in retroreflection geometry when secured to a KM200B kinematic platform mount with a PM4 clamping arm. By using this prism as a retroreflector, light is emitted parallel to the incoming light, regardless of its angle of incidence, while being inverted by 180°. This feature makes the PS990 an ideal replacement for a retroreflector or right-angle prism, especially in situations with limited space or when more convenient mounting options are needed.