Holographically Recorded Gratings

Holographically Recorded Gratings

The era of modern holography began in the 1960s with the use of lasers as coherent light sources. In 1967 the HORIBA Jobin Yvon engineering team, led by J. Flamand and A. Labeyrie, produced the first holographically-recorded diffraction gratings. Intensive R&D efforts led to HORIBA Jobin Yvon's production of holographically-produced aberration-corrected gratings, for which the company was awarded numerous international patents.

To manufacture holographic gratings, highly-polished and precisely-figured blanks (exceeding l/10 for many applications) are coated with a layer of photosensitive material, which are then exposed to fringes created by the interference of two coherent laser beams. Chemical treatment of the photosensitive layer selectively dissolves the exposed areas of the photoresist layer, forming grooves in relief.

Through careful design and configuration of the holographic recording apparatus, we can obtain plane and concave “Type I” gratings (parallel grooves, uniformly spaced), or “Type IV” gratings with variable-spaced grooves for full aberration correction. Optimization of the holographic recording geometry requires optomechanical stability far greater than most optical applications.

Recording a plane holographic grating

The shape of the grooves produced by holographic recording is typically sinusoidal or pseudo sinusoidal.

Sinusoidal Profile - AFM Image