Browse Prior Art Database

Structure for Making Phase Filters

IP.com Disclosure Number: IPCOM000077988D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 140K

Publishing Venue

IBM

Related People

Kirk, JP: AUTHOR

Abstract

This structure can be used to make optical phase filters, and particularly of the type which employ a surface modulated medium to alter the phase of an incident wave. Developed relief images of a photoemulsion have been employed for making optical phase filters, Because photoemulsions have a nonlinear spatial frequency response, complex exposure patterns are required to compensate the nonlinear response of the photoemulsion.

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Structure for Making Phase Filters

This structure can be used to make optical phase filters, and particularly of the type which employ a surface modulated medium to alter the phase of an incident wave. Developed relief images of a photoemulsion have been employed for making optical phase filters, Because photoemulsions have a nonlinear spatial frequency response, complex exposure patterns are required to compensate the nonlinear response of the photoemulsion.

In the present structure photopolymers having a uniform spatial frequency response are used.

As shown in Fig. 1, first there is provided a photoemulsion substrate which includes photoemulsion layer 11, containing a developed optical density image related to the desired phase modulation characteristic, transparent support 12, and transparent base plate 13 affixed to the bottom of support 12 by transparent adhesive 14. It is assumed that the density image has a sinusoidal density distribution, with spatial frequencies f1, f11, f111 in the regions designated a, b, c, respectively, where f1 < f11 < f111. The amplitudes are designated A1, A11, A111, respectively, where A11 > A1 > A111, because of the nonlinear spatial frequency response of photoemulsion layer 11.

Next, as shown in Fig. 2, transparent epoxy cement 15 is applied in its uncured state to the undulated surface of layer 11 and optically flat member 16 has its optically flat surface 17, which is coated with a suitable release agent brought into contact...