A method of determining a wavefront of a received light beam includes: (a) receiving a light beam; (b) producing a group of light spots from the light beam; (c) qualifying a set of the light spots for use in determining a wavefront of the received light beam; and (d) determining the wavefront of the received light beam using the qualified set of light spots. Qualifying the set of light spots includes, for each light spot: calculating a first calculated location of the light spot using a first calculation algorithm; calculating a second calculated location of the light spot using a second calculation algorithm; and when a difference between the first and second calculated locations for the light spot is greater than an agreement threshold, excluding the light spot from the set of light spots and/or from being employed in determining the wavefront of the received light beam.