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Browse Prior Art Database

Hologram Recording With A HeNe Laser

IP.com Disclosure Number: IPCOM000048663D
Original Publication Date: 1982-Mar-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bjorklund, GC: AUTHOR [+4]

Abstract

Benzocarbazole in a polymer host can be used to record holograms in the region 350-700 nm. This wavelength region includes the region of operation of the industrially important HeNe laser (632.8 nm), and the material disclosed here can be used to record holograms directly with such a laser.

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Hologram Recording With A HeNe Laser

Benzocarbazole in a polymer host can be used to record holograms in the region 350-700 nm. This wavelength region includes the region of operation of the industrially important HeNe laser (632.8 nm), and the material disclosed here can be used to record holograms directly with such a laser.

The holograms are recorded using the technique of four-level two photon photochemistry. Light at a frequency Omega(1) of a wavelength shorter than 375 nm excites the benzocarbazole to its lowest singlet state. The light at Omega(1) may be coherent light from a laser or incoherent light from a lamp. Its function is not to produce the hologram itself, but rather to gate the holographic recording process off or on by preparing the system, in this case benzocarbazole, in its metastable lowest triplet state. This triplet state (T(1)) is reached via rapid intersystem crossing from S (1). Even through the light at frequency Omega(1) may result in some photochemistry in the system, since there is only a single beam at this frequency, it cannot result in hologram production by itself.

The hologram is produced by two interfering beams at the frequency Omega(2). The frequency Omega(2) is chosen to be in the region of the triplet triplet absorption spectrum for benzocarbazole.

Absorption of an Omega(2) photon excites the benzocarbazole to a state from which irreversible photochemistry occurs. This irreversible photochemistry is responsible for the reco...