A low-order waveplate is an essential optical component, and its parameters significantly impact the performance of optical systems. 

I. Basic Parameters

Thickness: The thickness of a low-order waveplate is usually between 0.2mm and 0.5mm. It is mainly made of high-quality optical-grade crystalline materials such as Quartz or MgF2. 

Wavelength Range: It is applicable to a wide wavelength range, typically covering multiple bands from ultraviolet to near-infrared, such as 240nm to 2100nm. 

Phase Delay Levels: The low-order waveplate can produce multiple levels of phase delays, with common ones being a quarter-wave plate (λ/4) and a half-wave plate (λ/2). 

II. Optical Performance Parameters

Wavefront Distortion: It is one of the important indicators for measuring the optical performance of the waveplate. The wavefront distortion of a low-order waveplate is usually small, such as λ/8@632.8nm or even smaller, which helps maintain the imaging quality and clarity of the optical system. 

Delay Accuracy: This reflects the accuracy and stability of the phase delay of the waveplate. The delay accuracy of a low-order waveplate is relatively high, such as λ/120@632.8nm or λ/500@632.8nm, which can meet the requirements of precision optical systems. 

Parallelism: It is an indicator for measuring the flatness of the waveplate surface and the consistency of the optical axis direction. The parallelism of a low-order waveplate is usually high, such as less than 3arc seconds or even smaller.

Surface Smoothness: It reflects the smoothness and cleanliness of the waveplate surface. The surface smoothness of a low-order waveplate is relatively high, such as S/D 20-10 or better. 

Coating: In order to improve the light transmittance of the waveplate and reduce reflection loss, an anti-reflection coating (AR coating) is usually applied on its surface. 

III. Other Parameters

Size and Shape:

The size and shape of the low-order waveplate can be customized according to specific application requirements. Common sizes include diameters of 10mm, 12.7mm, 15mm, 20mm, 25.4mm, etc., and the shape is usually round or square.

Temperature Stability:

Although the temperature stability of a low-order waveplate is not as good as that of a zero-order waveplate, it can still meet the requirements in many applications. 

Laser Damage Threshold: 

A low-order waveplate has a high laser damage threshold and can withstand the illumination of high-power lasers without being damaged. This characteristic gives it broad application prospects in the field of high-power lasers.