Apparatus and method for angular colorimetry

An apparatus for measuring reflectance properties of an object, comprising:

• a sample stage for placement of the object
• a light source
• a detector configured to detect reflected light from the object;
• and
• a positioning device configured to at least one of rotate the light source at twice the angular rate as the sample stage while the detector remains fixed or to rotate the detector at twice the angular rate as the sample stage while the light source remains fixed.

An apparatus for measuring reflectance properties of an object having a front reflecting surface and a back reflecting surface, comprising:

• a sample stage for placement of the object
• a light source
• a detector configured to detect reflected light from the object;
• and
• a positioning device configured to vary the angle of incidence of the light from the light source on the object and ensure that specularly reflected light from the object is always direct towards the detector as the angle of incidence varies and the reflected light received at the detector includes a front surface reflection from the object and at least one back surface reflection from the object.

A method for measuring reflectance properties of an object having a front reflecting surface and at least one back reflecting surface, comprising:

• illuminating the object at varying angles of incidence;
• collecting reflected light from the front and back reflecting surfaces of the object at respective specularly reflected angles;
• wavelength resolving the reflected light into a color spectrum;
• and
• analyzing an intensity of the color spectrum as a function of wavelength.