Laser Speckle Reducer

Product Overview

The Laser Speckle Reducer utilizes a rotating phase plate (RPP) to reduce speckle patterns in laser illumination, improving imaging uniformity and contrast.
By dynamically modulating the laser phase, the system achieves temporal decorrelation of coherent light, transforming speckled laser spots into smooth, uniform illumination.

The speckle reducer is compatible with single-phase plate or dual-phase plate (static + rotating) configurations, depending on the application and required speckle reduction performance.

Working Principle

Concept and Structure:
A rotating phase plate is a type of random phase modulator, with a surface that exhibits a spatially random phase distribution. This distribution can be created using ground glass or a random phase mask.

When the phase plate rotates slowly, the transmitted wavefront changes over time, generating different random phase patterns at each moment.

Function and Effect:

(1) In a static phase plate configuration, the transmitted laser field has a fixed random phase, producing static speckle patterns on the imaging plane.

(2) When the phase plate rotates, the phase distribution varies over time, causing temporal changes in speckle patterns.

(3) If the detector exposure time is longer than the speckle variation cycle, the recorded intensity is a time-averaged distribution, which reduces coherence, eliminates speckles, and produces uniform laser illumination.

This process is known as temporal decorrelation.

Configurations

(1) Single-Phase Plate:

      Minimal optical loss

      Moderate speckle reduction performance

(2) Dual-Phase Plate (Static + Rotating):

     Enhanced speckle reduction

    Slightly higher optical energy loss

Key Features

(1) Selectable Configuration:
Choose between single-phase plate or dual-phase plate designs to balance speckle reduction efficiency and optical throughput.

(2) Integrated Beam Shaping Option:
When the static phase plate uses an engineered diffusive plate, the system can simultaneously achieve laser beam shaping and speckle reduction.

Compatible with engineered diffusive plates with diameters between 0.5 inch and 1 inch.

Custom diffusive plates can be selected according to customer requirements—please contact technical support for options.

Thorlabs Polymer Engineered Diffusers link: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1660

(3) Single-Phase Plate Compatibility:

Standard size: 0.5 inch diameter phase plate

Default installation: 220 grid phase plate

Custom grid selection available upon request—contact technical support.

Thorlabs AR-Coated, N-BK7 Ground Glass Diffusers link: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=6901

Applications

(1) Uniform laser illumination for microscopy and imaging systems

(2) Reduction of coherent speckle in laser-based displays or projection systems

(3) Enhancing image contrast in biomedical or industrial laser imaging

(4) Compatible with multi-wavelength or single-wavelength laser sources