Concave Grating Production via Ultra-Precision Turning
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Solution Overview
Problem
Current methods for producing concave or convex gratings for monochromators are limited by the need for complex replication processes, restrict design flexibility to specific wavelengths, and require subsequent ion bombardment for blazed gratings, making them time-consuming and expensive, with limitations in producing gratings for various wavelengths.
Innovation Solution
A method involving the mathematical determination of grid line coordinates on a rotating body using ultra-precision lathes to create concave or convex gratings, allowing for the production of gratings with arbitrarily definable wavelengths without the need for ion bombardment, by calculating intersection points of auxiliary surfaces with the body's surface, enabling the creation of blazed gratings directly during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If holographic method is used to produce concave gratings, then no further optical elements are required and compact construction is achieved, but the production of many identical gratings is time-consuming and expensive
Solution Approach 1:
The patent replaces the optical holographic interference method with a direct mechanical turning process using ultra-precision lathes. The lathe mechanically cuts the grating lines directly into the substrate, eliminating the need for complex holographic setups, photoresist coating, and multi-step replication processes. This mechanical substitution dramatically reduces production time and cost while maintaining the ability to produce concave gratings with high precision.
Solution Approach 2:
The patent extracts and eliminates the intermediate holographic replication steps from the manufacturing process. By using direct turning, it removes the photoresist application, holographic exposure, and complex replication stages, keeping only the essential grating line creation step. This extraction of unnecessary process steps directly addresses the productivity issue.
2Ease of manufacture
If holographic method is used, then concave grating production is simplified, but no blazed grating can be produced without subsequent ion bombardment
Solution Approach 1:
The patent merges the grating line creation and blazed facet formation into a single turning operation. By using a specially shaped cutting tool, both the grating lines and the blazed facets are cut simultaneously in one machining pass. This combination eliminates the need for separate ion bombardment steps to create blazed gratings, reducing process complexity while maintaining production simplicity.
Solution Approach 2:
The patent performs preliminary shaping of the cutting tool to include the blazed facet geometry. The tool is pre-configured with the desired facet angles and shapes, so that when it cuts the grating lines, the blazed structure is created automatically as part of the same operation. This preliminary preparation of the tool eliminates the need for subsequent ion bombardment to create blazed gratings.
3Adaptability or versatility
If limited laser wavelengths are used in holographic production, then design is restricted to specific wavelengths, but flexibility for various wavelengths is needed
Solution Approach 1:
The patent changes the fundamental parameter from optical wavelength dependency to mechanical dimension control. Instead of being constrained by available laser wavelengths, the grating pitch and geometry are directly controlled by mechanical measurements and tool settings on the ultra-precision lathe. This parameter change from optical to mechanical domain allows arbitrary wavelength design flexibility without manufacturing restrictions.
Solution Approach 2:
The patent replaces the optical interference pattern generation (which is wavelength-dependent) with direct mechanical cutting. The grating geometry is defined by mechanical tool paths and measurements rather than by laser wavelength and interference patterns. This substitution removes the wavelength limitation entirely, allowing gratings to be designed for any wavelength by simply adjusting the mechanical cutting parameters.
4Reliability
If complex replication process is used for mass production, then identical gratings can be produced, but the process becomes time-consuming and expensive
Solution Approach 1:
The patent extracts and removes the complex replication process entirely from the manufacturing workflow. Instead of creating one master grating and then replicating it multiple times through holographic exposure and photoresist processes, each grating is produced directly by turning. This extraction eliminates the replication steps while maintaining consistency through precise mechanical reproduction of the same tool paths and cutting parameters.
Solution Approach 2:
The patent enables each grating to be self-produced through direct turning without requiring a separate master template or replication process. The ultra-precision lathe with computer-controlled tool paths can directly create the final grating product from the substrate material itself. This self-service approach eliminates the need for complex replication infrastructure while maintaining high consistency through repeatable machining processes.
Data Source
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AI summary
A method for producing a concave or convex grating (1) for a monochromator. In order not to be subject to any restrictions in respect of a specific wavelength when designing the grating and, moreover, in order to be able to produce a blazed grating without a subsequent production step, provision is made according to the invention for the method to comprise the calculation of coordinates of grating points (6) of grating lines (2) on a rotary body (3) by virtue of points of intersection of a family of auxiliary surfaces with a surface of the rotary body (3) being determined, wherein the family of auxiliary surfaces are generated by a family of second order curves, which rotate about an axis of rotation (x) of the rotary body (3), the method furthermore comprising the feeding of the coordinates of the points of intersection or of the grating points (6) into a computer-controlled ultra-precise turning machine in order to turn a grating structure, which corresponds to circles centred about the axis of rotation (x) or to a spiral extending around the axis of rotation (10), into a main body which, at least in portions, has the form of the rotary body (3).