How to manufacture high-precision MICRO LAMINATED LENSES

How to Manufacture High-Precision MICRO LAMINATED LENSES (Technical Specification)

UltraOpto's high-precision MICRO LAMINATED LENSES are micro-optical components made by precisely laminating multiple ultra-thin optical lenses and processing them as a whole. The core advantage lies in the ability to achieve complex diopter control through the laminated structure, making them suitable for high-end applications such as micro-imaging, laser coupling, and medical endoscopes. The high-precision manufacturing requires strict control over each core process, from substrate selection to finished product inspection, forming a fully standardized control process. The following is a detailed manufacturing process and key points of precision control.

I. Core Manufacturing Premise: High-Precision Substrate Selection and Pre-treatment 

The substrate is the foundation for ensuring the accuracy of the laminated lens. It needs to take into account optical uniformity, thickness consistency, and compatibility for lamination. The pre-treatment stage must eliminate surface defects and residual stress. 

1. Substrate selection: High-purity optical glass (BK7, quartz) or optical polymers (PMMA, PC) are selected. The appropriate material is chosen based on the application band (visible light/deep ultraviolet) to ensure that the substrate's light transmittance is ≥ 95% and the refractive index uniformity deviation is ≤ ±0.0001. 

2. Substrate pretreatment: Firstly, ultra-thin lens blanks (single surface thickness 50-200 μm) are fabricated through laser cutting, with thickness tolerance controlled within ±1 μm. Then, they undergo ultrasonic cleaning (to remove surface impurities) and low-temperature annealing (400°C ± 5°C, to eliminate cutting stress), ensuring the lens surface is free of scratches and stains, and the flatness reaches λ/[email protected]. 

II. Core Manufacturing Processes: High-Precision Lamination and Integrated Molding 

1.The stacking accuracy directly determines the final optical performance of the lens. It is necessary to achieve precise alignment and gap-free bonding of multiple lens pieces, and avoid problems such as layer offset and bubble residue. The core process is divided into three key steps. 

Lamination alignment and bonding (core process) 

High-precision alignment and bonding equipment is adopted, based on machine vision positioning technology, to achieve precise alignment of multiple ultra-thin lenses. The bonding process strictly controls pressure and temperature to ensure no bubbles and no offset. 

Alignment accuracy control: Positioning accuracy ≤ 0.5 μm. The edge of the lens and the marking point are captured in real time by a CCD camera, and the optical axis and mechanical axis are automatically calibrated to prevent astigmatic deviation caused by layer misalignment. 

Bonding process: Optical-specific bonding adhesive (with refractive index matching the substrate, deviation ≤ ±0.001) is used. The adhesive thickness is uniform (5-10μm). The bonding pressure is controlled at 0.1-0.3MPa, and the bonding temperature is 60-80℃. The temperature is kept constant and pressure is maintained for 2-3 hours to ensure that the adhesive layer is free of bubbles and delamination. 

2. Integrated grinding and polishing processing 

The laminated lenses need to undergo integrated grinding and polishing to eliminate the traces of the interface between the layers, ensuring the smoothness of the lens surface and the accuracy of its shape, to meet the installation and optical transmission requirements of micro-devices. 

Coarse grinding and fine grinding: Using diamond micro-abrasives, the grinding and polishing accuracy is gradually refined to remove surface unevenness and interface marks, reducing the surface roughness to the sub-micron level. 

Fine polishing: Utilizing an asphalt polishing mold in conjunction with cerium oxide polishing liquid, the surface roughness after fine polishing is Ra ≤ 0.01 μm, and the surface shape accuracy reaches λ/30 @ 632.8 nm, ensuring no scattering or distortion of light transmission. 

3. Edge shaping and chamfering treatment 

For the size requirements of micro-stacked lenses (diameter 0.5 - 5mm), precise edge shaping is carried out to prevent edge chipping and scattering, ensuring installation compatibility. 

Shaping accuracy: 

Dimensional tolerance ≤ ±0.01mm. Laser cutting and diamond grinding wheel polishing are combined to ensure the lens edge is smooth and free of burrs. 

Chamfering treatment: 

A precise chamfer of 0.1-0.2mm × 45° is applied to reduce edge stress concentration, prevent chipping during use, and minimize light scattering loss at the edges. 

III. Key Precision Control: Coating and Full Process Inspection 

1.The coating process enhances optical performance, and full-process inspection ensures that the precision of each step meets the standards, preventing substandard products from entering the market. The core process is divided into two steps. 

Precision coating (optional) 

According to the application requirements, anti-reflection films, reflective films or filter films are coated on the surface of the lens. The thickness of the films is strictly controlled to improve the optical performance. 

Coating environment: Vacuum degree ≥ 10⁻⁴Pa, constant temperature and humidity (20 ± 0.1℃, 40 ± 5% RH), to avoid the influence of environmental impurities on the quality of the film layer. 

Film thickness control: The film thickness is monitored in real time by the crystal control instrument, with a deviation of ≤±2nm, ensuring that the transmittance (anti-reflection film ≥ 99.5%) or reflectance (reflective film ≥ 99.9%) meets the standards, and the adhesion of the film layer is ≥ 5B grade (ISO 15184 standard). 

2. High-precision inspection throughout the entire process 

From raw materials to finished products, each process undergoes random inspection or full inspection. The core inspection items and precision standards are as follows to ensure product consistency and stability. 

Base material inspection: Light transmittance, refractive index uniformity, surface defects (in compliance with MIL-PRF-13830B standard); 

Lamination inspection: alignment accuracy, bonding gap (≤0.1μm), no residual bubbles. 

Finished product inspection: surface shape accuracy, surface roughness, dimensional tolerance, optical performance (spherical power deviation ≤ ±0.01D). 

IV. UltraOpto's Advantages in High-Precision Manufacturing 

1. Equipment Assurance: We employ imported high-precision alignment and bonding machines, as well as ultra-precise grinding and polishing machines. The positioning accuracy and processing accuracy have reached the international advanced level. 

2. Process control: Set clear precision standards for each process, and equip with a professional quality control team to achieve full traceability throughout the process. 

3. Customized Adaptation: According to customer requirements, the number of layers, size, material and film system can be customized to adapt to different high-end micro-device scenarios. 

Through the above full-process high-precision manufacturing and control, UltraOpto MICRO LAMINATED LENSES can stably achieve complex diopter regulation, and possess the advantages of miniaturization, high precision and high stability, providing core component support for various high-end micro-optical systems.