Design of a variable attenuator and fabrication of its shutter element

A method for attenuating a beam of radiation, comprising:

• passing a beam of radiation from an input optical path to an output optical path;
• providing an optical element that transmits radiation, said element comprising a transparent substrate and an opaque layer thereon so that the radiation is transmitted only through areas of the substrate that are not covered by the opaque layer;
• turning a screw to displace a nut connected to the element relative to the beam moving said element along a direction that causes the beam to intercept a portion of the element interposed between the two paths, wherein the opaque layer forms a pattern such that intensity of radiation that is transmitted through the portion varies with a dimension of the portion of the element along said direction, so that the amount of attenuation applied to the beam passing between the two paths is controllable by controlling the dimension of the portion of the element along said direction intercepted by the beam;
• wherein said pattern is in the form of an opaque layer with holes therein or an opaque layer in the form of dots, or both.

A method for making an attenuator, comprising:

• forming a first layer of substantially opaque material on a transparent substrate;
• forming a second layer of radiation-sensitive material on the first layer;
• exposing the second layer to radiation to expose selected portions of the second layer according to a predetermined pattern;
• removing portions of the second layer that have been exposed to the radiation or portions of the second layer that have not been exposed to the radiation;
• assembling at least a portion of the first layer with the remaining portions of the second layer with optical components to form an attenuator.