The processing flow of ZOOM FIBER COLLIMATORS

ZOOM FIBER COLLIMATORS (Zoom Fiber Collimators) Processing Flow

ZOOM FIBER COLLIMATORS (Zoom Fiber Collimators) is a core passive optical device that can continuously and precisely adjust the focal length. Its core advantage lies in the ability to flexibly adjust the diameter of the collimated beam and the divergence angle without the need to replace optical components, making it suitable for various application scenarios. The processing flow of this product is centered on "high precision, high stability, and smooth zooming", integrating key processes such as precision optical processing, fiber handling, and adjustable structure assembly. The entire process adheres to a 10,000-level dust-free standard and strict quality control to ensure stable beam quality and low loss during the zooming process. It can be widely applied in laser processing, optical communication, spectral analysis, photovoltaic welding, and other fields. The following is a detailed description of the complete processing flow.

I. Preparatory Work and Raw Material Selection 

The quality of raw materials directly determines the optical performance and zoom reliability of the zoom collimator. In the early stage, it is necessary to focus on screening the core raw materials that are compatible with the zoom function. All raw materials must pass multiple rounds of quality inspection to prevent defective materials from entering the processing stage. 

1.1 Core Raw Material Screening 

Optical lens assembly: It adopts a two-piece lens combination design, consisting of a positive lens (plano-convex lens) and a negative lens (crescent lens), both made of high-transparency fused silica to ensure high transmittance, high-temperature resistance, and high-power resistance. The clear aperture is uniformly controlled at 25.4mm. The radius of curvature of the rear surface of the positive lens is -18.599mm, with a center thickness of 8.132mm and an aspheric coefficient of -0.793. The radii of curvature of the front and rear surfaces of the negative lens are -31.241mm and -105.969mm respectively, with a center thickness of 9.940mm. Through precise parameter matching, a focal length adjustable range of 30mm to 60mm is achieved. 

Fiber optic components: Square or round optical fibers are selected based on the application scenario, and the corresponding diameters are matched to ensure mode field matching with the lens assembly and reduce coupling loss. High-precision ceramic ferrules are paired, with the micro-hole diameter of the ferrule precisely matching the fiber cladding to fix the fiber and ensure alignment accuracy. At the same time, an 8° inclined end face processing space is reserved to further reduce the return loss. 

Structural components and auxiliary materials: A non-magnetic stainless steel casing is selected, with reserved sliding tracks for the lens and installation positions for the locking device to ensure smooth zoom adjustment and no loosening after locking. High-precision glass sleeves and capillaries are equipped to guarantee the coaxiality of the components. Low-shrinkage, high-temperature resistant UV-cured epoxy resin and inert gas (nitrogen) are chosen as auxiliary materials, respectively for component fixation and anti-oxidation protection during the processing. The adhesive should meet the requirements of low fluorescence and moisture resistance to ensure long-term stability. 

1.2 Raw Material Pretreatment 

Targeted pre-treatment is carried out on qualified raw materials throughout the operation in a 10,000-level dust-free workshop: the surface coating of optical fiber components is stripped to expose the pure fiber core, and dedicated cleaning equipment is used to remove surface dust and oil stains to avoid affecting the coupling efficiency; the lens components undergo rough grinding and fine grinding to ensure that the surface is free of scratches and cracks, and the flatness error of the end face is controlled within 0.1 μm to prepare for subsequent coating; structural parts (housing, glass sleeves, capillaries) are subjected to ultrasonic cleaning and drying to remove surface impurities, and then undergo anodic oxidation treatment to enhance corrosion resistance and wear resistance; all pre-treated raw materials are stored in a dust-free and dry environment to prevent secondary pollution. 

II. Core Processing Procedures 

1.The core processing procedures are the key to achieving the zoom function, mainly including three major links: precise lens processing and coating, optical fiber treatment, and precise processing of structural components. Each procedure requires the use of dedicated equipment and strict parameter control to ensure processing accuracy and zoom performance. 

Precision lens processing and coating 

The lens, as the core optical component of the zoom collimator, its processing accuracy and coating quality directly determine the collimation effect and zoom stability. The process is as follows: 

Lens fine grinding and polishing: Utilizing the molding process in combination with precision grinding equipment, the fused silica raw material is processed into positive and negative lenses with preset parameters. During the molding process, the lens glass is heated to the yield point temperature and formed under staged pressure, with temperature gradient control and inert gas protection to ensure the accuracy of the lens surface and parameter consistency. After processing, the lenses are finely polished through precision polishing equipment to achieve an optical-grade surface finish without any defects. At the same time, the parallelism error of the optical axes of the two lenses is guaranteed to be ≤ 0.3 μm, laying the foundation for zoom adjustment. 

Anti-reflection coating: Using vacuum coating technology, broadband anti-reflection coatings are applied to the surfaces of two lenses. According to the application wavelength, there are three specifications (A coating: 400-700nm, B coating: 650-1100nm, C coating: 1050-1650nm), ensuring an average reflectivity of the coating layer less than 0.5%, effectively reducing light reflection loss and enhancing light transmission efficiency. After coating, the lenses are subjected to high-temperature baking to enhance the adhesion of the coating layer, ensuring it does not fall off or age over long-term use, and is also resistant to high-power laser impact, suitable for common laser wavelengths such as 1064nm. 

2. Optical Fiber Processing 

The core of fiber processing is to ensure the efficient coupling of the fiber with the lens assembly and to avoid power leakage or fluctuation in loss during the zooming process. The process is as follows: 

Fiber optic end face processing: High-precision fiber optic cutting equipment is used to cut and polish the fiber optic end face, ensuring that the end face is flat and free of burrs, with a cutting angle error of less than 0.5°. For scenarios where it is necessary to reduce the return loss, the fiber optic end face is processed with an 8° tilt angle to prevent reflected light from damaging the fiber core and lens surface, further optimizing the optical performance. 

Optical fiber and ferrule fixation: Insert the processed optical fiber into the ceramic ferrule, adjust the position of the optical fiber to ensure that the coaxiality error between the fiber core and the ferrule center is ≤ 0.5 μm; use low-stress UV curing adhesive to fix the optical fiber and ferrule, and after curing, conduct baking treatment to eliminate the stress of the adhesive, prevent the optical fiber from shifting, and ensure long-term stability of use. 

3. Precision Machining of Structural Components 

The core of structural component processing is to ensure the smoothness of zoom adjustment and structural stability, and to avoid mechanical stress affecting optical performance: CNC precision processing equipment is used to process the stainless steel housing, lens sliding track, and locking device, with the inner diameter of the housing and the track size tolerance controlled within ±0.001mm; the track processing must be smooth without any jamming, to meet the sliding requirements of the lens assembly, and at the same time, the installation position of the locking screw is reserved to ensure that it can be quickly locked after zoom adjustment to prevent position deviation; after processing, the structural components are cleaned and dried to ensure there are no processing debris remaining. 

III. Precision Assembly and Zoom Adjustment 

The assembly and debugging procedures must be carried out in a 10,000-level dust-free workshop, with anti-static and anti-vibration operations throughout. The core is to achieve precise alignment of the lens assembly, fiber optic assembly and structural components, ensuring stable beam quality and smooth adjustment during the zooming process. It is divided into three steps: assembly, alignment and debugging, and zoom performance optimization. 

1.Precise assembly of components 

Assemble in the order of "housing → glass sleeve → optical fiber assembly → lens assembly → locking device": Fix the glass sleeve and optical fiber assembly inside the housing, ensuring a reasonable gap is reserved between the optical fiber end face and the lens assembly; install the coated positive and negative lenses on the sliding tracks respectively, adjust the position of the lenses to ensure that the optical axes of the two lenses are coaxial with the optical fiber core, with coaxiality error ≤ 0.3 μm; install the locking device, ensuring that the lenses do not loosen after locking, while not affecting the smoothness of the zoom adjustment; during the assembly process, avoid touching the lens surfaces and optical fiber end faces to prevent contamination or damage. 

2. High-precision alignment and debugging 

A six-dimensional high-precision adjustment platform, laser source and optical power meter, and beam quality analyzer are used to align and debug the collimator after assembly: The laser source (matched to the corresponding wavelength, such as 1064nm) is connected to the fiber end, and the optical power meter and beam quality analyzer are connected to the lens output end; by adjusting the relative position of the lens and the fiber, the coupling efficiency is optimized to ensure that the insertion loss is ≤ 0.3dB and the return loss is ≥ 45dB; at the same time, the beam divergence angle is monitored to ensure that the beam divergence angle in the initial collimation state meets the preset standard, the spot shape is uniform, and there is no stray light. 

3. Optimization of Zoom Performance 

Zoom performance optimization is the core debugging step of the zoom collimator: By rotating the adjustment handwheel, the lens assembly slides along the track, adjusting the distance between the first lens and the fiber output end face (l1 adjustable from 47.898mm to 59.977mm), and the distance between the second lens and the first lens (l2 adjustable from 83.351mm to 12.477mm), to achieve continuous adjustment of the focal length from 30mm to 60mm. Throughout the entire zoom range, the optical power, beam divergence angle, and spot quality are monitored in real time to ensure that the power loss fluctuation during zooming is ≤ 0.1dB, the beam pointing stability is < 1mrad (for FC/PC and FC/APC connectors), and the spot size can be correspondingly adjusted from 0.1mm to 10mm, reaching diffraction-limited performance. After the debugging is completed, the locking device is optimized to ensure that the zoom position does not shift after locking, and the adjustment handwheel operates smoothly without any stalling. 

IV. Full-process Quality Inspection and Factory Delivery 

1.The quality inspection of zoom fiber collimators runs through the entire manufacturing process. Before leaving the factory, they need to undergo multiple rounds of rigorous testing to ensure that each product meets industry standards and application requirements, with a focus on zoom performance and long-term stability. 

Inter-process inspection 

After each core process is completed, targeted inspections are carried out: after lens processing, the surface accuracy, surface finish and coating quality are inspected; after fiber processing, the end face flatness and coaxiality are inspected; after assembly, the component tightness and optical axis alignment accuracy are inspected; after debugging, the initial collimation performance and zoom smoothness are inspected. Unqualified products are immediately reworked or scrapped to prevent defects from flowing into the next process. 

2. Comprehensive factory inspection before shipment 

Optical performance testing: Professional equipment is used to test insertion loss, return loss, beam divergence angle, and coupling efficiency to ensure that all parameters meet the requirements of the product specification. Among them, the coupling efficiency is not less than 95%, the power loss fluctuation during the zooming process is ≤ 0.1 dB, and the wavefront error is < λ/10 (400 - 1650 nm). At the same time, the spot quality at different focal lengths is tested to ensure that the M2 factor is close to 1, achieving a high-quality collimation effect. 

Zoom performance testing: Continuously adjust the focal length over 300 times to test the smoothness of zooming and the stability of locking, ensuring no stalling or deviation, and that the focal length adjustment accuracy meets the preset standards. At the same time, test the stability of the beam direction during the zooming process to ensure that the pointing stability of the FC interface collimator is less than 1 mrad and that of the SMA interface is less than 4 mrad, meeting the requirements of different application scenarios. 

Environmental adaptability and reliability testing: Conduct high and low temperature tests (-40℃ to 85℃), humidity tests (relative humidity 95%), and vibration tests to ensure that the product can still operate normally under extreme conditions, with no loosening of the structure and no attenuation of optical performance; connect to a rated power laser source and run continuously for 24 hours to detect temperature changes in the product, component integrity, and ensure there is no end face damage, film layer peeling, or other issues, and can stably withstand high-power laser transmission. 

Appearance and dimension inspection: Check that the product's appearance is free of scratches and defects, the structural component dimensions meet the tolerance requirements, the fiber optic connectors (FC-PC, FC-APC, SMA, etc.) fit well, the adjustment handwheel and locking device operate smoothly, and the markings are clear and accurate. 

3. Packaging and leaving the factory 

All products that pass the inspection are packaged with professional anti-static, moisture-proof and anti-collision packaging. They are equipped with a locking adjustable wrench and spare screws. The product model, specification, focal length range, coating type, production date and inspection qualified mark are marked on the product shell and packaging. After packaging, they are stored in a dust-free and dry warehouse and are dispatched according to the order requirements to ensure that the products are not damaged during transportation and can be put into use directly upon delivery to the customer. At the same time, detailed user manuals are provided to guide customers in zoom adjustment and daily maintenance. 

V. Core Advantages of Processing Technology 

The processing technology of our company's ZOOM FIBER COLLIMATORS integrates multiple patented technologies and precise processing capabilities, with prominent core advantages: Firstly, it adopts a two-piece lens precisely matched design, featuring a simple and compact structure. It can continuously adjust the focal length without replacing optical components, offering strong versatility and controllable costs. Secondly, the combination of lens molding and broadband anti-reflection coating enhances light transmission and high-power resistance, ensuring stable beam quality during zooming. Thirdly, high-precision rail processing and six-dimensional alignment debugging guarantee smooth zooming and stable pointing, suitable for various application scenarios. Fourthly, the entire process is carried out in a dust-free environment and undergoes multiple rounds of quality inspection to ensure product consistency and long-term reliability, making it widely applicable in high-end fields such as laser processing, photovoltaic welding, optical communication, and spectral analysis.