It is constructed of two multi-order waveplates with their axis crossed. Thus, it performs as a zero-order waveplate because of the effect of two plates counteracting each other. It has wide temperature bandwidth and wavelength bandwidth properties. Because it is cemented, the damage threshold must be considered (about 10KW/cm2) when used.                       

Cemented or Optically Contacted Zero-Order Waveplate              

Specifications:                    
Material: Crystal Quartz          
Dimension Tolerance: +0.0, -0.2 mm              
Wavefront Distortion: < λ/8 @ 632.8 nm             
Retardation: λ/8, λ/4, λ/2 or λ (typical)                 
Retardation Tolerance: < λ/500 (typical)                

Wavelength Range: 400-2100 nm                
Parallelism: <1 arc second              
Surface Quality: 20-10 scratch and dig                

Airspaced Zero-order Waveplate        

Its performance is as good as cemented zero-order waveplate. Additionally, the air-spaced construction enables it is suitable for the high power laser application. The damage threshold is more than 500 MW/cm2.      

Specifications:         
Material: Crystal Quartz              
Dimension Tolerance: +0.0, -0.2 mm            
Wavefront Distortion: <λ/8 @ 632.8 nm              
Retardation: λ/8, λ/4, λ/2 or λ (typical)     
Retardation Tolerance: < λ/500 (typical)           
Wavelength Range: 240-2100 nm              
Parallelism: <1 arc second           
Surface Quality: 20-10 scratch and dig           

AR/AR Coating R<0.2% per face is available upon request.            
Other retardations are also available.