A Polish Technological Institute has developed customer oriented holographic volume diffraction phase gratings on dichromated gelatin. Holographic gratings technology consists of recording a linear fringe pattern resulted from interference of two light waves in the light sensitive material i.e. dichromated gelatin. Then, during a developing process of the gelatin the light intensity distribution is transformed into a refractive index volume distribution, which creates the diffractive structure of the grating.
The gratings have high ratio signal to noise and therefore are applied as precise spectral devices like imaging spectrometers, Raman spectrometers and laser resonators. The gelatin is sealed between glass/quartz plates, which extends its durability for many years. Antireflection layers are applied on both sides of the grating. Recording process is performed with spherical waves of radii from 150 to 300 cm (depending on lines frequency). The grating frequency can be selected between 200 and 1300 lines/mm. The wavelength range, grating frequency, and angle of incidence are interrelated parameters and have to be arranged by the producer and a customer to achieve the best shape of diffraction efficiency curve, which is a trade-off process. Maximal diffraction efficiency is between 70 and 90% with low level of scattered light.

Innovative Aspects:
Technology which offers outstanding performance:
- low noise
- non-standard
- consumer oriented gratings
- low cost.

 

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