一、玻璃透镜的制造方法
1、先前的方法：把熔化好的光学玻璃在成型过程中制成直径和需要加工的透镜直径略大一点的玻璃棒，然后按照镜片的厚度切割成片材。拿到专门的机械加工仪器上，按要求加工成成品。加工的过程主要是：粗磨，中磨，细磨，精磨，抛光，退火。粗磨至精磨的材料主要是各种不同细微性的金刚砂。抛光的方法，在要求不高的情况下，可以用火焰抛光。高级镜片必须用机械的方法，抛光的材料一般为氧化铈。
2、现在的方法是先用模具热压成型。主要是为了减少原始方法中加工带来的浪费以及提高工作效率。方法是：根据镜片品质确定好熔融态玻璃的品质，把在一定温度、粘滞状态的玻璃放入模具中，压制成型，最后退火。结果有两种：一是一次到位，成型品即可达到尺寸精度要求。极微的缺陷可通过镀膜弥补。对模具的要求非常高，就我所知目前国内尚不具备。这种产品可满足大多数的需要。镜片精度主要受模具精度的影响。二是成型品即为精度很高的毛坯，然后再按上述原始的方法进行机械加工，但加工量很少，可明显地提高生产效率。要求精度极高的产品多采用这种方法。镜片精度主要受机械加工仪器精度的影响。二、镀膜的基本知识
大家知道，任何物体对光线都有反射作用，这也是我们能看到东西的原因。对于镜片而言，为了使得光线能够完全透过镜头，在底片上完全反映自然的真实情况，镜头最好是各种光线完全穿过。优质的光学玻璃，其光线透过率可达到90%

以上，尚余的光损失就需要在透镜表面镀上膜来弥补。所以，在光学镜头上主要是镀减反射膜也叫增透膜。为了满足各种要求，往往需要镀多层膜。为了提高玻璃的抗划伤能力，最外面的一层往往是高硬度的膜。在实验室里，现代的工艺技术几乎可以达到光线百分之百通过。之所以这么说，是因为在实际使用中，镜头上会或多或少地受灰尘、脏物等的影响，使得透过镜头的光线减少。镀膜的方法很多，但常规的方法也就那么几种。

(一)、化学方法，包括溶胶—凝胶法、化学气相沉积等方法。根据膜的性质配制一定成分的溶液，然后：
1、浸镀。把洁净的玻璃加热到一定温度，然后放入配置好的化学溶液里，拿出，烘干。这种膜显然是双面膜。
2、喷镀。把配置好的膜溶液装在喷枪上，喷到洁净的、热的玻璃表面。烘干。玻璃体可以是移动或旋转，以增加膜的均匀性。可镀双面或单面。 (以前镜头镀膜有采用所谓的甩胶法，但由于不经济，现代工艺镀无机膜时已将其淘汰，但它仍然是镀有机膜的一种常用、成本低廉的方法)。
(二)、物理镀膜法。有真空蒸镀、离子镀膜、溅射镀膜(均可归结为物理气相沉积)等多种不同的形式。多用于镀金属膜、反射膜等。如镜子。通常，化学方法的镀膜强度一般低于物理方法，但随着镀膜技术尤其是近一、二十年的飞速发展，用化学或物理的方法达到的效果已经没有什么分别。只是有成本的区别罢了。以前，化学的方法只能镀一层膜，镀第二层时，由于温度的影响常会破坏上层膜，但现代的工艺已基本解决这一难题。

Basic Knowledge of Glass Lens Manufacturing and Coating
I. Methods for Manufacturing Glass Lenses
1. Traditional Method:
o Melted optical glass is formed into glass rods slightly larger in diameter than the required lenses.
o The rods are then sliced into sheets based on the desired lens thickness.
o The sheets are processed on specialized machinery to produce the final lens.
o Key steps in the process include:
 Rough grinding, medium grinding, fine grinding, precision grinding, polishing, and annealing.
o Materials used:
 Grinding: Various grades of diamond abrasives.
 Polishing: For lower precision requirements, flame polishing may suffice. For high-grade lenses, mechanical polishing is mandatory, typically using cerium oxide as the polishing agent.
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2. Modern Method:
o Utilizes hot pressing molds to minimize material waste and improve production efficiency.
o Process:
 Define the quality of molten glass based on lens requirements.
 Heat the glass to a viscous state, place it into a mold, and press it into shape.
 Perform annealing after molding.
o Outcomes of Modern Method:
 Direct precision molding:
 The molded lens meets dimensional accuracy directly.
 Minor defects can be corrected through coating.
 Requires extremely high-precision molds, which are not fully available domestically at present.
 Suitable for most lens applications, with precision largely determined by mold quality.
 Molding as high-precision blanks:
 The molded lens serves as a near-final product with high dimensional accuracy.
 Further mechanical processing (grinding, polishing) is minimal but ensures the highest precision.
 Commonly used for products requiring extremely high precision, with quality dependent on the accuracy of mechanical processing equipment.
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This dual approach enables manufacturers to cater to varying precision and efficiency needs in the production of glass lenses.

II. Basic Knowledge of Coating
It is well known that all objects reflect light, which is why we can see them. For lenses, the goal is to allow light to pass through completely and reflect the true, natural scene onto the film or sensor.
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1. Light Transmission and Coating
• High-quality optical glass can achieve a light transmittance of over 90%.
• However, some light is inevitably lost due to reflection. This loss can be mitigated by applying coatings on the lens surface.
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2. Common Coatings for Lenses
• Anti-Reflective Coatings (AR Coatings):
o Also known as transmission-enhancing coatings, they are primarily used to reduce reflection and improve light transmission.
o To meet various requirements, lenses are often coated with multiple layers.
• Hard Coatings:
o The outermost layer is typically a high-hardness coating to improve scratch resistance.
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3. Laboratory Techniques and Real-World Conditions
• In laboratory settings, modern technology can achieve nearly 100% light transmission through lenses.
• However, in practical use, factors such as dust and dirt on the lens surface reduce light transmission.
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4. Coating Methods
There are many techniques for applying coatings, but only a few are commonly used in practice. These methods are carefully selected to balance performance, durability, and cost.
By applying appropriate coatings, lenses can significantly enhance their performance, reduce reflection, and maintain durability in real-world conditions.
I. Chemical Methods
Chemical methods involve processes like the sol-gel method and chemical vapor deposition (CVD). A solution is prepared based on the properties of the desired coating, and the following techniques are used:
1. Dip Coating:
o The clean glass is heated to a specific temperature and then immersed in the prepared chemical solution.
o The glass is removed and dried.
o This process creates a coating on both sides of the glass.
2. Spray Coating:
o The prepared coating solution is loaded into a spray gun and sprayed onto the clean, heated surface of the glass.
o The glass is dried, and the process can be applied to both single-sided and double-sided coatings.
o The glass can be moved or rotated during the process to improve coating uniformity.
(Note: In the past, a method called "spin coating" was used for lens coatings. Although it has been replaced by modern techniques for inorganic coatings due to inefficiency, it remains a low-cost and commonly used method for organic coatings.)
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II. Physical Coating Methods
Physical methods include techniques like vacuum evaporation, ion plating, and sputter deposition, all of which fall under the category of physical vapor deposition (PVD).
• These methods are commonly used to coat metallic films or reflective coatings (e.g., mirrors).
• Compared to chemical methods, physical methods often produce stronger coatings.
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Comparison Between Chemical and Physical Methods
• Strength:
o Physical coatings tend to have higher strength than chemical coatings.
• Technological Advances:
o With rapid advancements in coating technologies over the past 10–20 years, the performance differences between chemical and physical coatings have become negligible.
• Cost Efficiency:
o The main distinction now lies in the cost, with each method offering its own advantages depending on the application.
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Challenges and Modern Solutions
• Historically, chemical methods could only apply one layer of coating.
• When attempting to add a second layer, temperature changes would often damage the first layer.
• Modern techniques have resolved this issue, enabling multi-layer coatings without compromising quality.
Both chemical and physical methods now provide reliable and high-quality coatings for various optical applications.